THE NAUTILUS

Volume 101, Number 1

January 30, 1987

ISSS 0028-1344

A quarterly devoted

to malacology.

UBKkm

FEB a 1987

Woods Hole, Mass.

EDITOR-IN-CHIEF

Dr. M. G. Harasewych

Division of Mollusks

National Museum of

Natural History

Smithsonian Institution

Washington, DC 20560

ASSOCIATE EDITOR

Dr. R. Tucker Abbott

American Malacologists, Inc.

P.O. Box 2255

Melbourne, FL 32902

CONSULTING EDITORS

Dr. William K. Emerson

Department of

Living Invertebrates

The .American Museum of

Natural History

New York, NY 10024

Mr. Samuel L. H. Fuller

1053 Mapleton Avenue

Suffield, CT 06078

Dr. Robert Hershler

Division of Mollusks

National Museum of

Natural History

Smithsonian Institution

Washington, DC 20560

Dr. Richard S. Houbrick

Division of Mollusks

National Museum of

Natural History

Smithsonian Institution

Washington, DC 20560

Mr, Richard I. Johnson

Department of Mollusks

Museum of Comparative Zoology

Harvard University

Cambridge, MA 02138

Dr. .'\urele La Rocque

Department of Geology

The Ohio State University

C:oiumbus, OH 43210

Dr. James H. McLean

Department of Malacology

Los Angeles County Museum of

Natural History

900 Exposition Boulevard

Los Angeles, CA 90007

Dr. Arthur S. Merrill

% Department of Mollusks

Museum of Comparative Zoology

Harvard University

Cambridge, MA 02138

Dr. Donald R. Moore

Division of Marine Geology

and Geophysics

Rosenstiel School of Marine and

.Atmospheric Science

University of Miami

4600 Rickenbacker Causeway

Miami, FL 33149

Mr. Richard E. Petit

P.O. Box 30

North Myrtle Beach, SC 29582

Dr. Edward J. Petuch

Department of Geology

Florida Atlantic University

Boca Raton, FL 33431

Dr. G. Alan Solem

Department of Invertebrates

Field Museum of Natural History

Chicago, IL 60605

Dr David H. Stansbery

Museum of Zoology

The Ohio State University

C:olumbus, OH 43210

Dr. Ruth D. Turner

Department of Mollusks

Museum of C^omparative Zoology

Harvard University

C:ambridge. MA 02138

Dr. Geerat J. Vermeij

Department of Biology

University of Maryland

College Park, MD 20740

Dr. Gilbert L. Voss

Division of Biology and Living

Resources

Rosenstiel School of Marine and

Atmospheric Science

University of Miami

4600 Rickenbacker Causeway

Miami, FL 33149

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THE NAUTILUS

Volume 101

1987

AUTHOR INDEX

Abbott, R. T 101

Batie, R. E 186

Berg. C J , Jr 19

Boss. K, J 45, 151

Bltm.an. B 19

D'.-\ttilio. .V 162

Davis. L. E 93

Early, J. A. 19

Emerso.\. W K 194

Fairbanks. H. L 86

H.arasewych, M. G 3, 48, 166

Hershler. R 25, 133

Houbrick. R, S 9, 80. 101, 155

Knight, R. L 93

KooL, S. 117

Longley, G 133

Lowell, R. B 69

Marks, J. A 69

Martin, R. F 75

McLean, J. H Ill

Merrill, .AS. 45

Mikkelsen. p. M 51

\1ikkelsen, p. S ■ 51

Myers, B. W 162

Petit, RE 48, 154

Petlch, E. J 200

Pip. E 33, 140

PooN. PA 88

QuiNN, J. F.. Jr .59, 111

Randall, C. W 75

Robertson, R 101

S,\GE, W E, III 194

Salnders. W. B 93, 188

Schmidt, J. E 182

Shasky. D, R 162

Theler, J. L 143

Thompson, F. G 25

ToLiN. W. A 182

TlRNER, R. D 19

\ krmeij, G. J 69

\\ alters. L. J 69

Ward, P. D 188

Zeto. M. .\ 182

NEW TAXA PROPOSED IN VOLUME 101 (1987)

GASTROPODA

Cataeginae McLean and Quinn, new subfamily (Trochidae) Ill

Cataegis McLean and Quinn, new genus (Trochidae) 113

Cataegis loreuta McLean and Quiiui, new species (Trochidae) 113

Cataegis mcroghjpta McLean and Quinn, new species (Trochidae) 115

Cataegis celebescnsis McLean and Quinn, new species (Trochidae) 115

Hadroconus Quinn. new genus (Seguenziidae) 61

Rotcllcnzia Quinn, new genus (Seguenziidae) 64

Asthelijs Quinn, new genus (Seguenziidae) 66

Phreatodrobia coronae Hershler. new species (Hydrobiidae) 133

Ataxocerithitim eximium Houbrick, new species (Cerithiopsidae) 157

PhijUonotus eversoni D'AttiUo, Myers and Shasky. new species (Muricidae) 162

Ecphora hradleyae Petuch, new species (Thaididae) 204

Ecphora hertweckunim Petuch, new species (Thaididae) 204

Tractoliru germonae Harasewsch, new species (Volutidae) 3

BenthoLoliita claydoni Harasevv\ch, new species (Turbiiiellidae) 173

CanccUaria quasiUa Petil. new name (Cancellariidae) 154

Cancvllaria (Mcrica) laddi Pclil. ricu name (C^ancellariidae) 154

THEC7NAUTILUS

Voltiiue 101. Number 1

Jamicny 30, 1987

ISSN 0028-1344

CONTENTS

M. G. Harasewych Tractolira germonae, A new abyssal Antarctic volute 3

Richard S. Houbriek Anatomy of Alaba and Litiopa (Prosobranchia:

Litiopidae): Systematic implications 9

Carl J. Berg, Jr., Seasonal recruitment of marine invertebrates to hard

Bradford Butman, substrates on Georges Bank and the eastern continental

Julie A. Early, and shelf of the United States 19

Ruth D. Turner

Robert Hershler and North American Hydrobiidae (Gastropoda: Rissoacea):

Fred G. Thompson Redescription and systematic relationships of Tryonia

Stimpson, 1865 and Pyrgulopsis Call and Pilsbry, 1886 25

Eva Pip Ecological differentiation within the genus Helisoma

(Gastropoda: Planorbidae) in central Canada 33

Kenneth J. Boss and The publication date of Solarium architae O. G. Costa 45

Arthur S. Merrill

M. G. Harasewych and The status of Tritonium viridulum Fabricius, 1780 48

Richard E. Petit

News and Notices 50

IJIariMBidB^UtaaHT i

LIBRARY j

FEB 11 19fiy

1 Woods Hole. Mass.

With the completion of Volume 100 of THE NAUTILUS, one dedicated to "all the molluscan enthusiasts, both private

conchoiogists and professional malacologists, who founded and carried on for the last 100 years America's oldest

journal devoted exclusively to the study of mollusks," Dr. R. Tucker Abbott retired as Editor-in-Chief. Under his

direction, first as co-editor (1958-69) then as editor (1970-86), THE NAUTILUS has prospered and grown for nearly

three decades. During his tenure as editor of THE NAUTILUS, R. Tucker Abbott also founded and edited Indo-

Pacific Molhtsca and Monographs of Marine Mollusca. In addition, Dr. Abbott has become the most prolific and

widely published malacological author of his generation, having written many landmark books on .\merican and

worldwide mollusks, several of which have been published in multiple editions, as well as a number of monographs

and numerous research papers. Having ushered THE NAUTILUS into its second century of publication. Dr. Abbott

will continue to serve as Associate Editor, but will devote more time to writing. Like preceding editors of THE

NAUTILUS, Dr. Abbott has earned an eminent position in the history of American malacology.

With a change in editorship, a number of other changes may be apparent, among them yet another change in

journal size, a new cover and format, expanded instructions to authors, a larger panel of consulting editors, and a

new publisher, Allen Press. For the new cover and format, we are greatly indebted to Hal Lewis Design, Inc. FinalK',

THE NAUTILUS, which had been privately owned in its first century of publication, is now published b\ Trophon

Corporation, a non-profit corporation established to publish works on mollusks.

Despite these changes, the purpose of this publication, that of "giving information of \ital interest to the student

of Mollusca", remains the same. As it begins its second century of service to the malacological community, THE

NAL TILLS will continue to meet ever higher standards in the publication of papers on all aspects of the biolog\- and

systematics of mollusks.

M. G. Harasewych

Editor

THE NAUTILUS 101(l):3-8, 1987

Page 3

Tractolira germonae, A New Abyssal Antarctic Volute

M. G. Harasewych

Department of Invertebrate Zoology

National Museum of Natural History

Smithsonian Institution

Washington, DC 20560, USA

ABSTRACT

Tractolira germonae, a new species of volute, is described

from abyssal depths along the Scotia Arc, and assigned to the

previously monotypic genus Tractolira on the basis of shell

and radular morphology. Anatomical characters of this new

species support the inclusion of Tractolira in the subfamily

Odontocymbiolinae, and suggest a close relationship between

the subfamilies Odontoc\mbiolinae and Zidoninae.

INTRODUCTION

The United States Antarctic Research Program (USARP)

has been conducting research, including the samphng

of Antarctic and Subantarctic biotas for nearly three

decades. A study of the abyssal gastropods collected by

USARP has uncovered a number of specimens of a new

species of volute, apparently endemic to the perimeter

of the Scotia Sea. This species described herein is as-

signed to the previously monotypic genus Tractolira Dall,

1896. The inclusion of Tractolira in the subfamily

Odontoc>mbiolinae by Weaver and duPont (1970:133)

rested on the statement by Dall (1907:365) that the now

lost radula of T. sparta Dall, 1896, the t\pe species from

the abyssal zone off western Central America, "is marked

by the same tusk-like cusps as are found in Miomelon",

one of the two genera originally included in the subfam-

ily. A description of the anatomy serves as the basis for

a discussion of the phylogenetic affinities of Tractolira

and Odontocymbiolinae.

SYSTEMATICS

Family Volutidae Rafinesque, 1815

Subfamily Odontocymbiolinae Clench and Turner, 1964

Genus Tractolira Dall, 1896

Tractolira gernwnae new species

(figures 1-3, 5-13; table 1)

Description: Shell (figures 1-3) to 60 mm, extremely

thin, translucent, elongate, fusiform, eroded where not

covered by periostracum (figures 5, 7). Protoconch badly

eroded on all specimens, with vestiges of projecting cal-

carella at ape.x. Shell with up to five moderately convex

whorls. Suture impressed. Spiral sculpture of 60-80 fine

threads on body whorl, 20-30 on preceding whorls, de-

creasing in prominence with increase in shell size. Axial

sculpture limited to fine growth striae. Aperture ovate.

Outer lip smooth, slightK' flared in larger specimens.

Inner lip smooth, with thin transparent inductura along

parietal region. Columella smooth, with raised white si-

phonal fold. Outer shell layer white to light tan, eroded

areas of shell white, aperture white. Periostracum (fig-

ure 5) thin, greenish brown. Inner shell surfaces smooth,

continuous.

Ultrastructure: Shell of three orthogonal layers of

crossed lamellar crystals: outer layer 20 ^lm thick, with

crystal faces perpendicular to growing edge; middle lay-

er 120 nm thick, with cr\stal planes colabrally aligned;

inner layer 12 yum thick, with crystal planes again per-

pendicular to growing edge. X-ray diffraction analysis

showed shell to be composed almost exclusively (> 99%)

of aragonite, with no significant amounts of calcite or

vaterite.

External anatomy: Soft parts comprise three whorls,

mantle cavity spans V2 whorl, kidney '/$ whorl, digestive

gland two whorls. Foot (L/W = 1.5) broad anteriorly,

tapering posteriorly, with deep propodial mucous gland

(figure 9, pmg). Operculum absent. Animal yellowish

tan, without visible color pattern in alcohol-preserved

material. Sole of foot deeply glandular, producing co-

pious mucus. Siphon (figure 9, s) muscular, free, about

1/5 shell length. Two ventral appendages, equal in length,

extend from base of siphon (figure 9, sa), one on each

side of left cephalic tentacle (figure 9, t). Head broad,

with short tentacles on each side of hood that extends

over rhynchostome. Outer edges of tentacles with broad

semicircular projections. Eyes absent.

Mantle cavity: Arrangement of mantle cavity organs

similar to that of Alcithoe arabica as described by Pon-

der (1970). Mantle edge thickened, muscular, smooth.

Osphradiuin with 46 filaments below and 60 above os-

phradeal ganglion. Ctenidium, of about 200 filaments,

slightly narrower (0.9 x ) and about 1.4 times as long as

osphradium. Hypobranchial gland deeply glandular,

producing purple secretion. Pericardium forms left rear

Page 4

THE NAUTILUS. Vol. 101, No. 1

igurcs 1-3. Tractulira gcrmomw new .species 1. Holotype, USNM 859076 2. Paratype 1, USNM 845611, both from Islas Orcada

a. 38, east of Candlemas Island, South Sandwich Island's, in 2,740-2,757 m. 3. Paratype 5, USNM 845612, Islas Orcada sta 51,

south of Candlemas Island, South Sandwich Islands, in 2,248-2,402 m. Figure 4. Traciolira sparta Dall, 1896 Holotype, USNM

122999, Albatross sta. 3360, Gulf of Panama, in 3,058 m, sand bottom. All figures 1.5 x.

F]

sta

wall of mantle cavity, ventricle diameter 2.5 x auricle

diameter.

Alimentary system: Proboscis short, broati, pleurem-

bolic, partially protruded in majority of specimens ex-

amined (figure 9, pb). Proboscis retractor muscles at-

tached to walls of cephalic hemocoel. Mouth (figures 9,

10, m) triangular. Buccal mass (figure 10, bm) muscular.

Radular ribbon short (5-7 mm), uniserial with 48-56

teeth, each with three tusk-like cusps. Central cusps

M G Harasewvch, 1987

Page 5

Figures 5-8. Tractolira germonae new species. 5. Periostracum, scale bar = 200 nm. Note erosion of shell where not covered by

periostracum. 6. Shell ultrastructure, fracture surface parallel to growing edge, scale bar = 25 fim. 7. Eroded surface of shell, scale

bar = 80 /im. 8. Radular ribbon, scale bar = 80 /im.

shorter and narrower than outer cusps (figure 8). Acces-

sory salivary glands (figure 10, asg) wrapped tightly

around salivary glands (figure 10, sg). Ducts of accessory

salivary glands join (figure 10, dasg) before entering

buccal cavity ventrally. Ducts of salivary glands run along

the esophagus, entering buccal cavity dorso-laterally.

Valve of Leiblein (figure 10, vl) large, nearly spherical.

Gland of Leiblein (figure 10, gl), long, tubular, highly

convoluted, fills posterior % of cephalic hemocoel. Pos-

terior esophagus (figure 10, pe) reflected dorsally before

joining U-shaped stomach. Section of stomach anterior

to single duct from digestive gland (figure 11, ddg) tu-

bular, with longitudinal folds. Posterior to digestive gland

duct, stomach forms caecum (figure 10, c), becoming

transversely pleated before joining intestine (figure 10,

int). Intestine with longitudinal folds, expands into pink

rectum (figure 10, r), with jade green anal gland (figure

10, ag) along distal '/s of its length. Anus (figure 10, a)

with muscular rim and ventral papilla.

Female reproductive system: Ovary ascinous, whitish,

on columellar side of digestive gland. Oviduct (figure

Page 6

THE NAUTILUS, Vol. 101, No. 1

11

pmg

12

rmc

asg

Figures 9-13. Anatomical features of Tractolira germonae new species. All figures 3.0 x. 9. .interior view of animal. 10.

Alimentary system, 11. Stomach, opened dorsally. 12. Female glandular oviduct. 13. Male pailial gonoduct.

a. anus; ag, albumen gland; asg, accessory salivary gland; be, bursa copulatrix; bm, buccal mass; c, caecum; eg, capsule gland; co,

connective tissue; dasg, duct accessory salivary gland; ddg, duct digestive gland; fo, female opening; gl, gland of Leiblein; ig,

ingesting gland; int, intestine; m, mouth; od, oviduct; pap, papilla; pb, proboscis; pe, posterior esophagus; pen, penis; pmg, propodial

mucous gland; pr, prostate gland; r, rectum; rg, rectal gland; rmc, rear mantle cavity; s, siphon; sa, siphonal appendage; sg, salivary

gland; sto, stomach; t, tentacle; td, testicular duct; vd, vas deferens; vl, valve of Leiblein.

12, od), thin, leading to rear of mantle cavity and en-

tering anterior ventral edge of albumen gland (figure

12, ag), which forms right wall of kidney Pailial oviduct

is joined by the purplish ingesting gland (figure 12, ig)

before expanding into capsule gland ( figure 12, eg). Bur-

sa copulatrix (figure 12, be) forms blind muscular di-

verticulum between female opening (figure 12, fo) and

capside gland.

Male reproductive system-. Testis yellowish tan, lines

right side of digestive gland. Testicular duct tubular,

passing along pericardium before entering mantle cav-

M. G. Harasewych, 1987

Page 7

ity. Prostate gland (figure 13, pr) slit ventrally, spans

posterior half of mantle cavity. Prostate and rectum sur-

rounded by connective tissue (figure 13, co) to form

cylindrical mass. Vas deferens (figure 13, vd) descends

to mantle Door, forming groove w ith fused edges that

runs to base of penis (figure 13, pen). Penis short, dor-

soventrally flattened, reflected posteriorly, with terminal

papilla (figure 13, pap). Penial duct as in Alcithoe ara-

bica (Ponder, 1970: fig. 32).

Kidney: Kidney similar to that of Alcithoe arabica

(Ponder, 1970: fig. 33), consisting of nephridial gland

adjacent to pericardium, heavily pleated dorsal area, and

ventral area with seven large lamellae. Latter two areas

each fed by branch of the renal vein. Kidney opening

over renal vein on left side of kidne\'. Reno-pericardial

opening at anterior upper left corner of kidney.

Nervous system: Nervous system Type 2 (Ponder, 1970:

159), with supraesophageal and right pleural ganglia

fused.

Etymology: This species honors Mrs. Raye N. Germon,

Department of Invertebrate Zoology, National Museum

of Natural History, Smithsonian Institution, for her con-

tributions to the study of Antarctic mollusks.

Type locality: East of Candlemas Island, South Sand-

wich Islands, 57°00.4'S, 27°10.1"W, in 2,740-2,757 m,

Islas Orcada Cruise 575, sta. 38, May 22, 1975.

Holotype: USNM 859076, 9, length 59.1 mm.

Paratypes: Paratypes 1-4, USNM 845611, from the tvpe

locality; paratvpes 5-10, USNM 845612, paratvpe'll,

ANSP A 11540, paratvpe 12, BM(NH) 198141, 57°22.6'S,

26°34.0'W, in 2,248-2,402 m, May 26, 1975, IO-575, sta.

51; paratypes 13-16, USNM 845613, 57°39.0'S,

26°00.4'W, in 2,380-2,609 m. May 27, 1975, IO-575, sta.

54; paratvpes 17-19, USNM 845614, 56°29.5'S,

26°46,9'W, in 2,248-2,387 m. May 30, 1975, 10-575, sta.

63; paratypes 20-29, USNM 845615, paratypes 30-31,

DMNH 169441, 56°03.5'S, 26°58.3'W, in 2,128-2,161 m,

June 3, 1975, IO-575, 53°25.2'S, 45°17.0°W, in 2,632-

2,691 m, June 12, 1975, IO-575, sta. 104.

Distribution: All live-collected specimens were taken

off the South Sandwich Islands, with one record, based

on shell fragments, from the Scotia Ridge. The con-

firmed bathymetric range for T. germonae is 2,161-

2,740 m, with a mean station depth (n = 6) of 2,449 m.

This species appears to be endemic to the Scotia Arc.

Ecology: All specimens of this abyssal species were tak-

en on mud bottoms. Upper whorls of even the smallest

specimens are eroded. The periostracum protects the

shell from dissolution (figure 5), as this species lives be-

low the aragonite compensation depth (Morse & Berner,

1979). A radular ribbon belonging to a naticid of the

genus Amauropsis (Powell, 1951: fig. J) was found in

the stomach of a dissected specimen.

Table 1. Tractolira germonae new species. Measurements of

shell and radular characters. Linear measurements in mm.

n = 10.

Comparative remarks: Tractolira germonae differs

from T. sparta Dall, its only living congener, in having

a broader, less elongate shell with a proportionally larger

aperture, in lacking axial ribs on the early whorls and

in having broader, less pronounced spiral sculpture. Nei-

ther preserved material of T. sparta nor the radula de-

scribed by Dall are available, and anatomical compari-

sons cannot be made, other than to note that the radula

of T. germonae resembles that of Miomelon philip-

piana (Dall, 1896) (Pilsbry & Olsson, 1954: pi. 3, fig. 9),

therein agreeing with Dall's (1907:365) description of

the radula of T. sparta. The holotype of Tractolira spar-

ta was illustrated by Dall (1908). The specimen figured

by Weaver and duPont (1970: pi. 56 G, H) as the ho-

lotype is a paratype (USNM 123000) from Malpelo Is-

land, Colombia. The holotype of T. sparta is figured

herein (figure 4).

DISCUSSION

Clench and Turner (1964:170) erected the taxon Odon-

tocymbiolinae, a replacement name for the subfamily

Adelomeloninae Pilsbry and Olsson (1954), to include

the South American genera Odontocymbiola and

Miomelon. Although some species in these genera

strongly resemble some members of the Zidoninae in

shell form, Odontocymbiolinae can be readily identified

by their characteristic radular teeth, which have "fang-

like" denticles. Other characters that serve to differen-

tiate the Odontocymbiolinae include the presence of the

long, symmetrical siphonal appendages, tubular acces-

sory salivary glands that are tightly wound around com-

pact salivary glands, a vas deferens that forms a closed

duct, a penis with closed duct and terminal papilla, and

a stomach with a tubular anterior region. Although fig-

ured (pi. 82, figure 36), the last feature was not discussed

by Clench and Turner (1964). Weaver and duPont (1970)

provisionally included the abyssal eastern Pacific genus

Tractolira and the Australian genus Volutoconus in

Odontocymbiolinae, largely on the basis of radular mor-

phology.

The inclusion of Tractolira in Odontocymbiolinae is

further supported by features of the salivary glands, ac-

cessory salivary glands, stomach, and male reproductive

Pages

THE NAUTILUS, Vol. 101, No. 1

system. Although fang-like cusps are present in Trac-

tolira, they are not as elaborately modified as in some

other members of the subfamily (Weaver & duPont,

1970: figure 27). The protoconch of Tractolira, with its

pointed calcarella, more closely corresponds to that of

Adelometon ancilla (Solander, 1786) (Clench & Turner,

1964: pi. 93), a member of the Zidoninae, than to those

of Odontocymbiolinae (Clench & Turner, 1964: pi. 82,

fig. 35). The penis of Tractolira has the duct and papilla

of Odontocymbiolinae, but resembles that of Zidoninae

in size and disposition.

In view of the numerous similarities in anatomy and

shell morphology between the Zidoninae and Odonto-

cymbiolinae (Clench & Turner, 1964), and because the

character states that have been used to distinguish the

Odontocymbiolinae are clearly derived from homolo-

gous features in the Zidoninae, it is suggested that these

two subfamilies are sister groups, with the Odontocym-

biolinae being derived from the Zidoninae, and that

Tractolira is a primitive genus within the Odonto-

cymbiolinae. Zoogeographic distributions of Recent

species (Weaver & duPont, 1970) further suggest that

the Zidoninae radiated in the Austral Province (Kauff-

man, 1973) during the Cretaceous, while the geograph-

ically more restricted Odontocymbiolinae evolved in the

Weddellian Province (Zinsmeister, 1979, 1982) after the

separation of New Zealand at the end of the Early Pa-

leocene.

Dall (1907:365) proposed "Valuta" alta Sowerby,

1844, from shallow water early Tertiary deposits of Chile,

as an ancestor of Tractolira. It is here proposed that the

genus Tractolira colonized the abyssal regions of the

Peru Basin during the early Tertiary, and that speciation

of T. germonae is due to vicariance resulting from the

displacement of tectonic fragments from the Pacific hin-

terland of the Andean-West Antarctic Cordillera into

the southwestern Atlantic during the Cenozoic (Dalziel

& Elliot, 1973).

ACKNOWLEDGEMENTS

The assistance of Mr. Victor Krantz with specimen pho-

tography, Mrs. Susann Braden with scanning electron

microscopy, and Mrs. Molly Kelly Ryan with illustration

is gratefully acknowledged. I thank Dr. Thomas Waller

for helpful discussions and comments on an earl\ draft

of the manuscript.

LITERATURE CITED

Clench, W. J. and R. D. Turner, 1964. The subfamilies V'olu-

tinae, Zidoninae, Odontocymbiolinae and Calliotectinae

in the western Atlantic. Johnsonia 4(43):129-180,

Dall, \\ . li 1896. Diagnoses of new species of mollusks from

the west coast of America. Proceedings of the United States

National Museum 18:7-20.

Dall, W. H. 1907. A review of the American Volutidae.

Smithsonian Miscellaneous Collections 48(.3):34 1-373.

Dall, VV. H. 1908. Reports on the dredging operations off the

west coast of Central .-America to the Galapagos, to the

west coast of Mexico, and in the Gulf of C^alifornia, in the

charge of Alexander .Agassiz, carried on by the U.S. Fish

Commission steamer "Albatross during 1891, Lieut.

Commander Z. L. Tanner, U.S.N., Commanding,

XXXVIII. and Reports on the scientific results of the ex-

pedition to the eastern tropical Pacific in charge of Alex-

ander Agassiz, by the U.S. Fish Commission steamer "Al-

batross", from October, 1904, to March, 190.5, Lieut.

Commander L. M. Garrett, U.S.N., Commanding, XIV.

Reports on the Mollusca and Brachiopoda. Bulletin of the

Museum of Comparative Zoology 43(6):205-487, pis. 1-

22.

Dalziel, I. W. D. and D. H. Elliot 1973 Evolution of the

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Journal of Paleontology 56(1 ):84-102.

THE NAUTILUS 101(1):9-18, 1987

Page 9

Anatomy of Alaba and Litiopa (Prosobranchia: Litiopidae):

Systematic Implications

Richard S. Houbrick

Department of Invertebrate Zoology

National Museum of Natural History

Smithsonian Institution

Washington, DC 20560, USA

ABSTRACT

Anatomical study of Litiopa and Alaba shows that these taxa

differ from other cerithiaceans by a significant number of syn-

apomorphies. These two taxa have been variously assigned to

the Planaxidae, Litiopidae, Diastomidae, Rissoidae, Cerithi-

idae, and to a number of subfamilies of the latter family Both

genera are highly adapted to algal habitats and have a meso-

podial mucous gland on the sole of the foot that produces long,

anchoring mucus threads preventing dislodgement from the

algae. They share similar taenioglossate radulae; many-whorled,

ribbed protoconchs; nearly identical pallial oviducts; egg masses;

and planktotrophic larvae. Both genera stand apart from other

cerithiacean groups in having long, tapered, epipodial tenta-

cles. The morphological evidence points to a close relationship

between the two taxa and also supports their inclusion in the

family Litiopidae Fischer, 1885.

INTRODUCTION

The higher taxonomic assignment of many small species

of cerithiacean snails is controversial and frustrating.

Convergent shell characters and lack of anatomical

knowledge about the various taxa have resulted in an

unstable classification. Moreover, many of the published

systematic opinions about genera and families of ceri-

thiaceans are based on vague, equivocal, conchological

characters. I have discussed the taxonomic problems of

small, heterogeneous cerithiacean taxa elsewhere (Hou-

brick, 1980:4-5, 1981:610-611). This paper deals with

the anatomy of Litiopa Rang, 1829, Alaba H. and A.

Adams, 1853, and several related taxa, and presents an-

atomical data for their natural systeinatic arrangement.

Litiopa, while usually assigned to the family Litiopidae,

has been thought to be related to the Planaxidae, Ris-

soidae, or Cerithiidae by various authors. Alaba has like-

wise been referred to the Cerithiopsidae, Planaxidae,

Dialidae, Litiopidae, Diastomatidae, Cerithiidae, and to

a number of subfamilies of the latter family. Bandel

(1984:55) has discussed the confusing literature regard-

ing the placement of Alaba. The status of a few other

genera such as Stijliferina A. Adams, I860, and Diffal-

aba Iredale, 1936 remains uncertain. The genus Diala

A. Adams, 1861 is frequently considered a close relative

of both Alaba and Litiopa and has been grouped with

them (A. Adams, 1862; Smith, 1875:538) or placed in its

own family, Dialidae (Hornung & Mermoud, 1928). Dall

(1889:258) suggested that Alaba was related to Bittium

Gray and Diastoma Deshayes. Other workers, such as

Wenz (1938) and Franc (1968), have included Finclla

A. Adams, Alabina Dall, and Alaba with the Diasto-

matidae. A summary of the various taxonomic alloca-

tions of Alaba and Litiopa is presented in table 1. Most

workers have referred the two taxa to the subfamily

Litiopinae and placed this group under the Cerithiidae

Bruguiere, 1789.

MATERIALS AND METHODS

Living specimens of Litiopa melanostoma Rang, 1829

and Alaba incerta (Orbignv, 1842) were studied at the

Smithsonian Marine Station at Link Port, Ft. Pierce,

Florida during January, Februar\, and April of 1986.

Litiopa melanostoma was collected offshore on Sargas-

sum weed. Alaba incerta was collected from intertidal

marine grass beds in St. Lucie Inlet, Florida, and on

shallow water grass beds around Peanut Island in Lake

Worth, Riviera Beach, Florida. Living snails were main-

tained in petri dishes of sea water and relaxed in a 10%

MgCL solution for study under a binocular dissecting

microscope. Snails were preserved in Bouin s seawater

fixative, embedded in paraffin, sectioned at 7 ^m, and

stained with Alcian blue-PAS and counterstained in he-

matoxylin (Humason, 1962:269). Critical point dried an-

imals extracted from shells, radular ribbons, and proto-

conchs were examined under a Novascan-30 scanning

electron microscope to determine inicroscopic anatom-

ical features. Protoconchs of some Australaba and Fi-

nella species were also compared with those of litiopids.

MORPHOLOGY

Shell morphology: Members of both genera are small,

not exceeding 25 mm in length, and have moderately

turreted, conical, thin, nearly transparent shells. The shell

Page 10

THE NAUTILUS, Vol. 101, No. 1

Figures 1-3. Animal of Alaba incerta. 1. Operculum, showing sinuous attachment ridge, by transparency. 2. Ventral view,

showing sole of foot and disposition of epipodial tentacles. 3. Side view of female, showing ciliated groove and ovipositor on right

side of head-foot (bar = 1 mm), ag = albumen gland; eg = capsule gland; cgr = ciliated groove; cm = columellar muscle; ct =

cephalic tentacle; dg = digestive gland; e = eye; et = epipodial tentacle; etl = epipodial tentacular lobe; k = kidney; m = mouth;

me = mantle edge; mmg = mesopodial mucous gland; op = operculum; ov = ovary; ovp = ovipositor; pmg = propodial mucous

gland; pt = propodial tentacle; r = rectum; sn = snout; sf = sole of foot.

of Alaha (figure 11) differs from that of Litiopa (figure

9) in being longer and in having irregularly distributed,

wide varices and a taller, more turreted apex. In Litiopa,

the whorls are more inflated and fewer in number than

in Alaba, and the shell is tan-yellow while that of Alaba

is vitreous and white. Litiopa has a wider aperture and

a weak tooth at the base of the columella. Both taxa

have tiny brown subsutural spots and flammules, but

Alaba also has weak, spiral bands of tan spots. Litiopa

and Alaba have nearly identical protoconchs comprising

3.5-4 whorls (figures 8, 10). Protoconch 1 is smooth (pit-

ted under high magnification) while protoconch II is

sculptured with numerous axial riblets divided by a thin

spiral thread from a band of subsutural plaits. Micro-

scopic spiral lines lie between the axial riblets in Litiopa

(figure 8). A good figure of Litiopa melanostoma and

its protoconch has been given by Okutani et al. (1983:

24, figs. 1-5). Robertson (1971:5, pis. 2, 3) presented

detailed figures of the protoconchs of Alaba incerta and

Litiopa melanostoma. The periostraca of both taxa are

thin and transparent. The ovate, paucispiral opercula

are completely transparent and have eccentric nuclei in

both taxa. Only the portions of the opercula beneath the

nuclei are attached to the metapodia by fine sinuous

ridges (figure 1). This opercular attachment scar is clear-

ly depicted by Robertson (1971;pl. 4, fig. 16), who noted

R. S. Houbrick, 1987

Page 1 1

the similarity of the opercula of both taxa. A ridge-hke

attachment scar is also described for Alaba goniochila

by Kosuge (1964:36, fig. 6).

External anatomy: Litiopa and Alaba are very active

snails and move about quickly in the algae or on the

underside of the surface film of the water, on which

they glide shell down by means of their long foot. E.\-

ternally, Litiopa is yellow with a pale foot while Alaba

has a whitish base color flecked with olive brown and

red spots. The slender cephalic and pedal tentacles are

striped with reddish brown in Alaba. A conspicuous fea-

ture in both genera is the long, narrow, active foot which

is used to climb about algal filaments and fronds. A very

deep, anterior propodial mucous gland lies at the lead-

ing edge of the sole (figures 2, 3, 7, 15, pmg) and a large,

mesopodial mucous gland is centrally located at the pos-

terior of the sole (figures 2, 3, 7, 12, 15, mmg). The

propodial mucous gland produces a sheet of mucus that

moves posteriorly along the sole of the foot. Scanning

electron micrographs of critical point dried snails show

that the sole of the foot is covered with long, dense, cilia

(figure 17). The mesopodial mucous gland is defined by

a slit-like groove (figures 2, 3, 7, 12, 15, mmg) that pro-

duces a strong mucus thread attaching the snail to the

substrate or surface film of the water. If accidentally

pulled or dislodged from their algal habitat, litiopids

cling to the mucus thread in spider-like fashion, em-

ploying the foot and mouth to crawl back and reestab-

lish themselves. The mucus thread is quite strong and

tensile. The mesopodial mucous gland occurs in both

genera, but is especially well-developed in the pelagic

snail, Litiopa. Neither of these anatomical features was

noted by Kosuge (1964), although he depicted a longi-

tudinal groove on the sole. A. Adams (1862) was the first

to note the mesopodial mucous gland in Alaba. but his

comments on the gland and its use in the spinning of

mucus threads have been overlooked by subsequent

workers. He also remarked that Alaba was similar to

Litiopa in this respect. A small, median, mesopodial mu-

cous gland that opens by a short duct to the posterior

portion of the sole also occurs in the Turritellidae (Ran-

dies, 1900:57).

Another conspicuous feature in litiopids, and espe-

cially in Alaba, is the presence of long epipodial tenta-

cles along the sides of the foot (figures 2, 3, 15, 16, et),

as noted by A. Adams (1862). The leading edge of the

propodium has a pair of small, short tentacles, one on

each side (figures 2, 3, pt). A lobe of epipodial tissue

runs along the postero-lateral part of the metapodium,

adjacent to the edge of the sole and supports the epi-

podial tentacles and operculum (figure 2, etl). The major

epipodial tentacles are long and tapered. A pair occurs

on the left side of the foot and a single one is on the

right side. A single tentacle is also at the posterior of the

foot. Other smaller tentacles flank the major tentacles.

When Alaba is viewed dorsally, the long right epipodial

tentacle emerges from the exhalant siphon. Epipodial

and cephalic tentacles have circular ridges along their

lengths (figures 15, 16, et, ct). These ridges are not seen

osb

Figures J-, 5. Litiopid pallia! oviducts (distal end on left;

bar = 0.3 mm). 4-. Litiopa melanostoma. 5. Alaba incerta

(dotted lines 1 and 2 represent cuts corresponding to diagram-

matic cross sections 1 and 2). acg = anterior ciliated groove;

ag = albumen gland; eg = capsule gland; 11 = lateral lamina;

ml = medial lamina; odg = oviductal groove; osb = opening

to spermatophore bursa; osr = opening to seminal receptacle;

sb = spermatophore bursa; sg = sperm groove; sr = seminal

receptacle

on living snails and may be the result of contraction of

the tentacles. A. Adams (1862) described a pair of epi-

podial tentacles on each side of the foot and a posterior

pair in Alaba picta A. Adams, 1861. Kosuge (1964:36,

figs. 1, 2) illustrated slender epipodial tentacles extend-

ing well beyond the shell margin of Alaba goniochila.

In Litiopa, the epipodial tentacles are much shorter and

less conspicuous.

The small head has a moderately extensible bilobed

snout and a pair of long, tapered cephalic tentacles (fig-

ures 2, 3, 6, 15, ct) that are extremely retractile and

touch the substrate alternately while the snail is crawl-

ing. The black e\es are surrounded by yellow pigment

and located on the outer edge of the tentacular peduncle

(figures 2, 3, e). The eyes are tiny and the tentacular

bases have no peduncular bulge in Litiopa. The mantle

edge of litiopids is smooth and bifurcate (figures 3, 15,

me). Females have a ciliated groove (figures 3, 15, cgr)

that emerges from the distal pallial oviduct, runs down

the right side of the head-foot, and ends at the foot edge

Page 12

THE NAUTILUS, Vol. 101, No. 1

-V rt'\.

^■^ -^

vl^lw

■xj i^x.l'myng

Figure 6. Litiopa melanostoma and egg mass on Sargassum leaf (ct = cephalic tentacle; em = egg mass). Figure 7. Sagittal

section through foot of Alaba incerta, showing operculum (op), mesopodial mucous gland (mmg), duct opening (Immg), and

propodial mucous gland (pmg) (bar = 0.5 mm). Figure 8. Protoconch of Litiopa melanostoma, showing sinusigeral notch (bar =

80 /jm). Figure 9. .\dult shell of Litiopa melamistoma from off Ft. Pierce, Florida (length 7 mm). Figure 10. Protoconch of

Alaba incerta, showing sinusigeral notch (bar = 80 ;uni). Figure II. Adult shell of Alaha incerta from St. Lucie Inlet, Florida

(length 15 mm). Figure 12. Transverse section of Alaha incerta showing buccal mass (bm), foot (f), large mesopodial mucous

gland (mmg), and lumen of duct (Immg) (bar = 0.5 mm) Figure 13. Radula of Litiopa melanostoma (bar = 20 ^lm). Figure

14. Details of rachidian, lateral, and marginal teeth of Litiopa melanostoma (bar = 16 Mni).

R. S. Houbrick, 1987

Page 13

adjacent to the sole, where a fleshy glandular pad, the

ovipositor (figure 3, ovp), is situated. The ovipositor is

especially well-developed in Litiopa. Okutani et al.

(1983:24, fig. 6) depicted the groove but not the ovipos-

itor.

The coils of the body whorl comprise the digestive

gland, gonad, stomach, and kidney and are typically

cerithioid in groundplan.

Mantle cavity organs: Litiopid snails have a deep man-

tle cavity dominated by a large ctenidium. A ridge-like

monopectinate osphradium extends the full length of

the ctenidium. Ctenidial filaments are long, tapered, tri-

angular, and have many long cilia. Similar observations

were made by Kosuge (1964:34) on Alaba goniochila.

The narrow hypobranchial gland is thick, and in Alaba

secretes an iridescent green substance when the snail is

injured or irritated. The rectum is thin walled and pro-

duces large ovoid fecal pellets that are tapered at one

end. The glandular pallial gonoducts are large and thick

in females but small and thin in males.

Alimentary tract: The buccal mass of litiopids is large

in relation to the snout size and has a pair of semicircular

jaws. The radular ribbon of Alaba comprises 35-40 rows

of teeth (n = 6) and is about one-fourth the shell length.

The large buccal mass of Alaba was also noted by

Kosuge (1964:34). The radulae of Alaba (figures 18-20)

and Litiopa (figures 13, 14) are taenioglossate

(2-l-H-H-l -1-2) and typically cerithioid, closely resem-

bling the radulae of Cerithiidae in overall morphology.

The rachidian tooth of Alaba (figure 19, r) is wider than

long, has a straight anterior front, and an hourglass-

shaped basal plate with a prominent central triangular

buttress. This hourglass shape is also found in some gen-

era and species of the Cerithiidae (Houbrick, 1980). The

cutting edge of the rachidian has a sharply pointed cen-

tral cusp flanked on each side by a pair of smaller den-

ticles. The lateral tooth (figure 19, 1) is trapezoidal and

has a basal plate with a long lateral basal extension and

a strong, ventral, inner buttress. The cutting edge has a

long central cusp, one inner denticle, with two outer

denticles in Alaba (figure 19, 1), and two to four in Li-

tiopa (figure 13). The marginal teeth of both genera

(figures 13, 14, 18-20) are equal in length, scythe-shaped,

and have cusped, spoon-like tips. The inner marginal

tooth is about twice as broad as the outer and has two

inner denticles, a long terminal cusp, and one outer den-

ticle. The narrow outer marginal has 4-5 inner denticles

in Alaba (figure 20), 8-9 in Litiopa (figure 13), a long

terminal cusp, and a smooth outer edge. The radula of

Alaba incerta has been described and figured in detail

by Bandel (1984:39-40, fig. 71, pi. 4, figs. 1, 9).

The mouth (figures 2, 15, m) and oral cavity are large

and manipulate long strands of filamentous algae in Ala-

ba and large Sargassum particles in Litiopa. The radula

of Alaba goniochila is very similar to that of Alaba in-

certa (Kosuge, 1964:36, figs. 7-10).

Litiopids have a pair of tubular, uncoiled salivary

glands that originate well behind the nerve ring and pass

through it before emptying into the buccal cavity. Sal-

ivary gland tubes are thicker in Litiopa than in Alaba.

A large esophageal gland, formed by outpocketing of

the lateral walls of the midesophagus, is present in Li-

tiopa. This was also found in Alaba incerta and was

noted by Kosuge (1964:34) in Alaba goniochila. The

stomach of litiopids has a large central ridge, a gastric

shield, and a short style sac. Although not seen in dis-

sections, histological sections show that a crystalline style

is present. The stomach of Alaba goniochila has been

depicted by Kosuge (1964:36, fig. 5), and is similar to

Alaba incerta. Sections show that the major typhlosole

extends well into the proximal intestine.

Reproductive tract: Litiopa and Alaba are typically

cerithiacean in having open gonoducts and aphallate

males. The pallial oviducts of both taxa consist of a thick-

walled, slit tube attached along its dorsal side to the

mantle wall (figures 4, 5). It comprises two laminae, a

lateral one attached along its width to the mantle wall

(figures 4, 5, II) and a medial, free lamina (figures 4, 5,

ml). Along the longitudinal base of the laminae is the

oviductal groove, which is wide and shallow (figures 4,

5, odg). The bulk of the pallial oviduct is dominated by

a large swollen, proximal albumen gland (figure 5, ag)

and by the adjacent distal capsule gland (figures 4, 5,

eg). These glands have a mucus-like consistency and

quickly swell with water when cut or injured. The al-

bumen gland is more opaque than the capsule gland

and stains a deep blue in section. The free medial lamina

has a sperm groove along its median edge (figures 4, 5,

sg) that enters into a small, proximal bursa (figures 4, 5,

sb). In Litiopa. the bursa leads into a small pouch that

appears to have a tiny opening on the inner side of the

medial lamina (figure 4, osr). In the lateral lamina, im-

mediately adjacent to this opening, is a pit-shaped pouch

that is probably the seminal receptacle (figure 4, sr). The

seminal receptacle is a round, deep chamber in Litiopa

(figure 5, sr) while it is a compact pouch in Alaba.

Eggs and larvae: The egg masses of Litiopa and Alaba

are similar, forming flattened, gelatinous, clockwise spi-

rals comprising one to four tight turns. Spawn masses of

Alaba vary in size but average about 4.8 mm in diameter

(n = 6). Unwound, an egg mass of this dimension com-

prises a ribbon 18.5 mm long and 0.35 mm wide. A

ribbon has 2-3 layers of very small eggs, about six across

the ribbon width, and contains about 4,800 eggs. Each

egg is 60 |im in diameter and is enclosed in a clear

hyaline capsule about 80 ^im in diameter. This, in turn,

is enclosed in an irregularly shaped gelatinous chamber

about 0.13 mm across. The jelly chambers are covered

in a gelatinous sheet forming a ribbon which is wound

into a spiral which slightly overlaps the previous spirals.

Jelly chambers and their enclosed eggs are tightly packed

in the central region of the ribbon. The egg mass of

Litiopa is deposited on Sargassum fronds (figure 6, em)

and is similar to but smaller than that of Alaba. mea-

suring about 2.5 mm in diameter and having fewer,

broader spirals.

Page 14

THE NAUTILUS, Vol. 101, No. 1

Egg masses of Alaba picta have been depicted by

Habe (1960:122, fig. 4; cited as Australaba picta), Amio

(1963:306, fig. 26), and Bandel (1976:262). Their figures

conform witfi observations of Alaba incerta spawn. The

egg mass of Litiopa has been poorly figured by Lebour

(1945:467-468, fig. 8a) who described it as a flat circular

mass. She did not note the spiral arrangement of the

jelly ribbon.

Development is rapid in both genera, the trochophore

stage being attained in 2 days and early veliger stages

within 3 days. Hatching takes place in about 6 days and

is preceded by disintegration of the egg mass. Freed

veligers are active swimmers and have a large bilobed

velum with long cilia and a transparent shell. Lebour

(1945:467, fig. 8c) depicted velar lobes of very unequal

size in Litiopa and stated that it is one of the commonest

veligers in open water plankton. The larval shell of Ala-

ba has a reddish brown columella. Bandel's (1976:262)

observations on Alaba from Santa Marta, Colombia, are

essentially in agreement with mine. He noted that it

takes a female about 90 minutes to produce a 2 cm long

ribbon.

The many-whorled, sculptured protoconchs with deep

sinusigeral notches (figure 10) seen on the apex of adult

snails of both taxa indicate a long planktotrophic phase

before settlement. The protoconchs of Litiopa and Ala-

ba are nearly identical in having many axial riblets. The

protoconch of Litiopa has microscopic spiral lines be-

tween the riblets and comprises about five sculptured

whorls (figure 8) while in Alaba, there are only three

whorls (figure 10). The larger protoconch of Litiopa in-

dicates a long planktonic phase that is reflected in the

pan-tropical distribution of this pelagic species. Robert-

son (1971:5) noted the close resemblance between the

protoconchs of Litiopa and Alaba and pointed out that

full grown larval shells of Litiopa are larger than those

of Alaba. He also noted the spiral lines ("crests") be-

tween the axial ribs on Litiopa protoconchs. The litiopid

protoconch is distinctive among cerithiaceans and ap-

pears to be a good familial taxonomic character.

Nervous system: Litiopids have an epiathroid nervous

system. A statocyst occurs on the posterior of each pedal

ganglion. The cerebral ganglia are joined by a very short

commissure and the pleural ganglia are closely joined to

the cerebrals. The subesophageal ganglion, although

completely separated from the left pleural ganglion, is

only separated from it by a very short connective. Zygo-

neury does not occur. The supraesophageal ganglion is

embedded in the left wall of the cephalic cavity. The

RPG ratio (Davis et al., 1976:263) was 0.43 (n = 2) in

Litiopa, indicating a tightly organized nerve ring. This

is the lowest ratio observed among the Cerithiacea, but

the low value may be a reflection of the small body size

of litiopids, and its significance is questionable.

SYSTEMATIC CONCLUSIONS

Below is a family diagnosis and synonymies suggested

for the genera Litiopa and Alaba. The synonymy for

Alaba is tentative and needs confirmation by careful

conchological and anatomical examination of the type-

species of each taxon.

Family Litiopidae Fischer, 1885

Diagnosis: Shell small, thin, having weak, shallow an-

terior canal and protoconch sculptured with numerous

axial riblets and subsutural plaits. Animal with epipodial

tentacles, smooth mantle edge, mesopodial mucus gland,

ridge-like osphradium, large esophageal gland, short

sperm gutter, and seminal receptacle in lateral lamina

of pallial oviduct.

Genus Litiopa Rang

Diagnosis: Shell moderately turreted, yellow-brown in

color, with inflated, weakly sculptured whorls and ovate

aperture with weak tooth at base of columella. Proto-

conch sculptured with microscopic spiral lines between

axial riblets. Animal yellow with well-developed ovipos-

itor on right side of foot in females. Seminal receptacle

a deep round chamber in posterior lateral lamina of

pallial oviduct.

Litiopa Rang, 1829:306. Type-species: Litiopa melanostoma

Rang, 1829, by SD, Nevill, 1884.

Bombijxintis Belanger in Lesson, 1835:32. T\pe-species: Litio-

pa melanostoma Rang, 1829, bv OD.

Bombycinus (emend, pro Bombyxinus Belanger, 1835) Agas-

siz, 1846:104.

Genus Alaba H. and A. Adams

Diagnosis: Shell \itreous, white, weakly sculptured, with

quadrangular aperture and very weak anterior canal;

thick varices present on several whorls. Protoconch with

numerous axial riblets. Seminal receptacle a compact

pouch in posterior lateral lamina of pallial oviduct.

Alaba H. and A. Adams, 1853:241. Tvpe-species: Rissoa me-

laneura C. B. Adams, 1850, by SD (Nevill, 1885).

Gihhorissoa Cossmann in Sacco, 1895:34. Type-species: ,Bu/i-

mu.'i costcllala Grateloupe, 1828, by OD.

Diffalaha Iredale, 1936:290. Tvpe-species: Diff alaba opiniosa

Iredale, 1936, bv OD.

Figures 15-20. Alaba incerta, animal and radula. 15. Critical point dried head-foot, showing sole and mucous glands, ct =

cephalic tentacle; et = epipodial tentacle; cgr = ciliated groove; m = mouth; me = mantle edge; mmg = mesopodial mucous

gland; pmg = propodial mucous gland (bar = 240 urn). 16. Detail of epipodial tentacles on critical point dried snail, et = epipodial

tentacle (bar = 40 urn). 17. Dense cilia on sole of foot (bar = 4 ^m) 18. l?adula ribbon with marginal teeth spread back (bar =

40 ^m). 19. Detail of rachidian (r) and lateral (1) teeth (bar = 20 ^m) 20. Inner and outer marginal teeth (bar = 20 /um).

R. S. Houbrick, 1987

Page 15

Litiopa

Alaba

Litiopinae

Litiopinae

Litiopinae

Litiopinae

Litiopinae

Litiopinae

Litiopinae

Litiopinae

Litiopinae

Litiopinae

Diastominae

Cerithiopsinae

Planaxidae

Litiopidae

Planaxidae

Cerithiidae

Cerithiidae

Cerithiidae

Cerithiidae

Cerithiidae

Litiopidae

Planaxidae

Cerithiopsidae

Cerithiidae

Cerithiidae

Cerithiidae

Dialidae

Cerithiidae

Cerithiidae

Diastomidae

Rissoidae

Tryon (1882:246-247)

Fischer (1887:718-719)

Cossmann (1906:196-197)

Thiele (1929:210-211)

Wenz (1938:753)

Franc (1968:281)

Keen (1971:415-416)

Abbott (1974:108)

Iredale and McMichael (1962:43)

Tryon (1882:246-247)

H. and A. Adams (1853:239)

E. A. Smith (1875:537)

Thiele (1929:210-211)

Wenz (1938:753)

Iredale and McMichael (1962:43)

Keen (1971:415-416)

Abbott (1974:108)

Kilburn and Rippey (1982:537)

Laseron (1956:459)

Obstopalia Iredale, 1936:299. Tvpe-species: Obstopalia lixa

Iredale, 1936, by OD.

Australaba Laseron, 1956:459. Type-species: Australaba bo-

wenensis Laseron, 1956, by OD.

Stijliferina A. Adams, 1860:.335. Type-species: Styliferina or-

thochila A. Adams, 1860, by OD.

Dialessa Iredale, 1955:81. Tvpe-species: Alaba transhicida

Hedley, 1906, by OD.

DISCUSSION

No comprehensive anatomical studies of Litiopa or Ala-

ba have previously been made. The earliest descriptions

of the superficial anatomy and habits of Alaba were by

A. Adams (1862), who described the animal of Alaba

picta, a Japanese species living in shallow water Zostera

beds. Adams (1862) pointed out the unusual features,

such as epipodial tentacles and the mesopodial mucous

gland, and noted that Litiopa shared these characters.

He considered Diala and Styliferina as subgenera of

Alaba and grouped all three in the family Litiopidae.

His paper has been overlooked by subsequent workers.

The genus Styliferina was originally described by A.

Adams (1860:335), who later considered it a subgenus

of Alaba A. Adams, 1862.

There are two short recent papers on the anatomy of

litiopids; one by Kosuge (1964) on Alaba goniochila, and

a few brief notes on Litiopa melanostonm In Okutani

et al. (1983). Ponder (1985:104) has noted that in Ko-

suge's (1964) paper, Alaba goniochila is incorrectly cited

as Diala goniochila, and likely to be overlooked in the

literature for this reason. Furthermore, this paper ma\

mislead others to include the genus Diala with the Li-

tiopidae. There can be no doubt that the species show n

by Kosuge (1964) is an Alaba and not a Diala, for his

description and figures unequivocally depict epipodial

tentacles. I was previously misled by this paper when I

incorrectly stated that Diala snails have epipodial ten-

tacles (Houbrick, 1980:4). Living Diala species exam-

ined in Queensland, Australia, did not have epipodial

tentacles. It is thus clear that Diala is not closely related

to Litiopa or Alaba and should not be referred to the

Litiopidae. In the brief paper by Okutani et al. (1983)

on Litiopa, only a radular drawing and a sketch of the

head-foot were presented. The authors did not note the

epipodial tentacles or the metapodial mucous gland, and

incorrectly stated that there was no modification for pe-

lagic life.

Although only two genera are now unequivocally in-

cluded in Litiopidae, other species and genera of small

cerithiaceans may prove to be members of this group

when their anatomy is better studied. The type of Fi-

nella xanthacme (Melvill, 1904) [= Obtortio] has a pro-

toconch like that of Litiopa, but no epipodial tentacles

(Ponder, personal communication). Ponder (1967:197,

pi. 10, figs. 7-9) has depicted the radula and operculum

of Alaba (Dialessa) transhicida (Hedle\), strongly sug-

gesting that the subgenus Dialessa is a litiopid. He later

considered Dialessa to be a litiopid (Ponder, 1985:104)

and has stated that Dialessa has an AlabaAike animal

(Ponder, personal communication).

Much of the anatomy of litiopids is similar to that of

the cerithiids. The long extensible foot observed in li-

tiopids also occurs in Bittium species from similar algal

habitats. The ovate, paucispiral operculum w ith eccen-

tric nucleus is also like that of Cerithium species. The

ciliated groove and ovipositor on the right of the foot of

females occur in Cerithiidae, in the genera Cerithium,

Bittium (Marcus & Marcus, 1964:507), and Rhinoclavis

(personal observation); in Potamididae. in Batillaria

(personal observation) and Cerithidea (Houbrick, 1984:

3); and in the Modulidae and Thiaridae (Houbrick, 1984:

10). The large esophageal gland is also present in most

members of the Cerithiidae (Houbrick, 1985:29) and

R. S. Houbrick, 1987

Page 1'

Modulidae (Houbrick, 1980:126). Litiopids, however,

differ from members of the Cerithiidae in having a

smooth mantle edge and in lacking a bipectinate os-

phradium. Bandel {1984:55). on the basis of radular con-

figuration alone, erroneous!) placed Alaba close to Cer-

ithium. However, a number of significant, apomorphic,

anatomical characters separate litiopids from other cer-

ithiacean families and define them as a unique group

that should be gi\en familial recognition. These include:

1) a median posterior, metapodial mucous gland that

produces a strong mucus thread, anchoring the snail to

its algal habitat [a mesopodial mucous gland also exists

in the Turritellidae (Randies, 1900:57), but does not pro-

duce a mucus thread and is probably a convergence]; 2)

location of the seminal receptacle in the lateral lamina

of the pallial oviduct; 3) an extremely short, distal sperm

gutter in the medial lamina of the pallial oviduct; 4)

long, retractile epipodial tentacles along the sides and

posterior of the foot; and 5) an unusual protoconch

sculptured with numerous axial riblets and subsutural

plaits. Other distinguishing characters are: 1) a very deep

propodial cleft into which the anterior mucous gland

empties; 2) extremely long, slender cephalic tentacles;

3) a long extensible, narrow foot; 4) an operculum with

a narrow spiral ridge on the attached surface; 5) an

hourglass-shaped rachidian tooth with a strong trian-

gular buttress; 6) large, swollen albumen and capsule

glands in the pallial oviduct; and 7) mound-shaped egg

masses comprised of tightly coiled jelly ribbons.

The hypothesis that Litiopa and Alaba are closely re-

lated had been previously suggested by A. Adams (1862)

and Robertson (1971). Anatomical, radular, and con-

chological e\idence resulting from this stud\' supports

this hypothesis. The two genera are herein allocated to

the family Litiopidae, as defined by the shared, derived

characters described above.

ACKNOWLEDGEMENTS

Much of this work was supported by a grant from the

Smithsonian's Marine Station at Link Port, Florida. I

thank the following station staff for their help in this

project: Hugh Reichart for assistance with photography,

Woody Lee for histology, Julie Piraino for help on the

SEM, and June Jones for computer assistance. This is

Smithsonian Marine Station Contribution 172. I also

thank Ms. Diane Bohmhauer of the National Museum

of Natural History, Smithsonian Institution, for assis-

tance with histology and proofreading the manuscript.

Dr. Robert Hershler, National Museum of Natural His-

tory, Smithsonian Institution, criticalh reviewed the

manuscript.

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the Marine Biological Station of Asamushi 10(2):121-126.

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THE NAUTILUS, Vol. 101, No. 1

Houbric'k, R. S. 1984. Revision of higher taxa in genus Cer-

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THE NAUTILUS 101(1 ):19-24, 1987

Page 19

Seasonal Recruitment of Marine Invertebrates to

Hard Substrates on Georges Bank and the Eastern

Continental Shelf of the United States

Carl J. Berg, Jr.

Marine Biological Laboratory

Woods Hole, MA 02543, USA

Bradford Butman

U.S. Geological Survey

Woods Hofe. MA 02543, USA

Julie A. Early

Marine Biological Laborator\

Woods Hole. MA 02543, USA

Ruth D. Turner

Harvard University

Cambridge, MA 02138, USA

ABSTRACT

Seasonal recruitment of marine invertebrates to hard substrates

placed on the U.S. continental shelf from 1978 to 1981 was

studied. A large fouling community was present at the bottom

of Georges Bank and distinct patterns of settlement were ob-

served for wood-boring pholads {Xylophaga). barnacles (Chi-

rona hameri). and jingle shells (Anomia squamula)- Seasonal

changes in gonadal development of the pholads suggested late

summer and late fall spawnings. Examination of wood samples

from 85 stations helped to document the bath\ metric and geo-

graphic distribution of nine species of pholads and eight species

of teredinids on the US continental shelf.

Key words: Recruitment; in\ertebrate larvae; hard substrates;

wood panels; boring organisms; settlement; continental shelf;

Georges Bank.

INTRODUCTION

This study was designed to examine patterns of seasonal

recruitment of marine invertebrates to hard substrates

on the continental shelf. It was conducted in conjunction

with studies of sediment transport on the eastern United

States continental shelf (Butman & Folger, 1979). Wood

was chosen as the substrate so that organisms that live

both in (wood-boring mollusks) and on hard substrates

could be studied. Annual recruitment of animals with

planktonic larvae could serve as a natural biological in-

dicator of the effects of oil and gas drilling activities on

the continental shelf.

MATERIALS AND METHODS

Settling panels of soft spruce (3.6 x 8.7 x 31.0 cm)

were attached with plastic straps to bottom tripod sys-

tems designed to measure processes of bottom-sediment

movement on the continental shelf (Butman & Folger,

1979). Samples were obtained from a total of 12 stations

over a 3-year period (table 1; figures 1, 2). The bottom

tripod systems measured water temperature, current,

pressure, and light transmission, and photographed the

seafloor every few hours (Butman & Folger, 1979). Panels

were strapped to the tripods in a horizontal orientation

approximately 1 m above the seafloor. Tripods were de-

ployed for periods averaging 4 months duration (figure

2).'

The entire panels were preserved in approximately

7% formalin seawater soon after the tripods were re-

covered. They were later examined under a dissecting

microscope to determine species and number of individ-

uals present, and to estimate the percent surface covered

by each species. The presence of larvae or newly set

juveniles was noted. Examples of each species were re-

moved and stored in ethanol for identification. Wood

borers were dissected from the panels, identified to

species, and their shells removed. Tissues were embed-

ded in paraffin, sectioned at 7 ^m, stained with hema-

toxN'lin and eosin using standard histological procedures,

and analyzed for gonadal ripeness.

Another set of samples of wood borers was obtained

from the L^.S. National Marine Fisheries Service (NMFS),

which collected wood in its sampling gear during sur-

veys of fisheries stocks on the continental shelf. Over a

5-year period (1976-81) a total of 142 pieces of wood

was obtained from 85 stations, ranging from 34°N to

42°N at depths of 18 to 183 m (figure 1).

A third set of samples was received from a joint NMFS-

USGS submarine cruise at 360 m on the continental slope

near 39°03'N, 72°46'W (July, 1978). Wood borers dis-

sected from all of these samples were treated identically

to those obtained from the tripod panels.

Page 20

THE NAUTILUS, Vol. 101, No. 1

^.

Table 1. Depth and location of monitoring stations.

♦i4f

39^

s®

•/32"

ing pholads {Xylophaga atlantica Richards, 1942), but

other species occurred as well (table 2). Greatest surface

cover, nearly 90% at times, was provided by A. squa-

mula, C. hameri, and the suite of hvdroid species (table

2).

The timing of larval settlement was determined from

the number and size of animals on the panels. The pres-

ence of larval forms or newly metamorphosed juveniles

indicated that recruitment, but not necessarily spawn-

ing, had just occurred. The presence of large animals

suggested that recruitment occurred during the early

part of panel deployment, but because little is known of

growth rates of invertebrates on the continental shelf,

exact timing of recruitment could not be determined.

Panels that were submerged for short periods (e.g., a

panel deployed for 26 days at Station P in October,

1978) provided better resolution of the timing of re-

cruitment than panels deployed for the average 4-month

Figure 1. Eastern continental shelf of the I'nited States with

offshore 200-m contour line. Shading indicates area surveyed

by the U.S. National Marine Fisheries Service during this study.

Locations of the U.S. Geological Survey long-term monitoring

stations are indicated by dots and their appro.ximate latitudes.

Exact locations of stations are given in table 1.

RESULTS

Georges Bank

(Five Stations, 64 to 99 m)

The number and species of fouling organisms on each

panel were dependent on a number of factors including

recruitment, competition, predation, and succession.

However, obvious patterns in colonization were ob-

served over the 3-year (1978-82) sampling period. The

most consistently present organisms on the wood panels

were jingle shells {Anomia squamula Linne, 1758), bar-

nacles (Chirona hameri Ascanius, 1767), and wood-bor-

W J S N J W M

Figure 2. Sampling periods of U.S. Geological Survey tripods

on the continental shelf of the eastern United States. Station

locations are listed in table 1 and shown in figure 1.

C. J. Berg, Jr. ct al.. 1987

Page 21

Table 2. Fouling organisms present on wood panels from

Georges Bank

Cnidarians Hsdrozoans Tubularia crocea (L. Agassiz,

1862)

Tubularia couthomji L. Agas-

siz, 1862

Pennaria tiarella (Avres,

1854)

Clijtia edwardsi (Nutting,

1901)

Anthozoans Metridium senile (Linne,

1758)

Annelids Polychaetes Lepidonotus squamatus

(Linne, 1758)

Antinoe sarsi (Kinberg, 1855)

Arthropods Pvcnogonids Callipallene brevirostris

(Johnson, 1837)

Cirrepedia Chirona hameri (Ascanius,

1767)

Amphipods Gammarus annulatus Smith,

1874

Caprellids Aeginina longicornis (Kroy-

er, 1843)

Mollusks Eolids Eubranchua pallidus (Alder

and Hancock, 1842)

Bivalves Anomia squamula Linne,

1758

Xijlophaga atlantica Rich-

ards, 1942

X. species 1, 2, 3, 4 (Turner,

ms.)

Placopecten magellanicus

(Gmehn, 1791)

Ectoprocts

Microporella eiliata (Pallas,

1766)

Barentsia laxa Kirkpatrick,

1890

period. Finally, because the timing of deployment var-

ied slightly each year, different periods were sampled.

Interpretation of the data was difficult, but the repeat-

ability of distinct periods of settlement during the 3 years

of the study sampled is remarkable (figure 3).

Newly set larvae of Anomia squamula occurred on

panels recovered in October and March; animals with

shells less than 2 mm occurred on panels recovered in

April and the beginning of June. Large numbers of an-

imals settled on the panels deployed from October to

May, with little or no recruitment during the summer

months.

Chirona hameri cyprid larvae and newly metamor-

phosed juveniles were collected in May, June, and Au-

gust, suggesting spring and summer recruitment. Panels

deployed during fall and winter were notably free of

barnacles.

Xylophaga atlantica larvae or juveniles less than 1

mm in shell length were collected in October, Decem-

ber, early March, and August. Panels deployed in the

spring, during periods of coldest bottom-water temper-

40r

:0

20

10

SNJMMJSNJMMJSNJM

600

400

I5°C

10°

5°

IMMJ5NJMMJSNJMM

ANOMIA

ir -h 6 ir

!l000

800

600

400

200

Figure 3. Mean seasonal abundance of Anomia squamula,

Chirona hameri, and Xylophaga atlantica on fouling panels

recovered from the Georges Bank. Stars indicate periods of

settlement as determined by the presence of newly settled an-

imals on the panels.

The mean monthly bottom-water temperatures measured by

the tripod systems are shown in the middle graph. Tempera-

tures indicated by solid dots (•) are from Station A, circles (O)

from Station K, open squares (D) from Station Q, and open

triangles (A) from Station LC. For a more detailed description

of the seasonal cycle of temperature at Station A on Georges

Bank, see Butman and Beardsley (in press).

atures on the Georges Bank (figure 3), had the least

amount of recruitment. This same pattern was observed

for the scallop Placopecten magellanicus Gmelin, 1791,

which was collected only from October to mid-March

and again from August to January.

Mid-Atlantic Region

(45 Stations, 41 to 234 m)

The single panel submerged at the shallow-water station

on the Middle Atlantic Bight (41 m) from October, 1978

to March, 1979 was covered with hydroids and mud

tubes. Fifty-nine specimens of Xylopholas altenae Tur-

ner, 1972 less than 1.56 mm in shell length and a few

large Anomia squamula (8.5 mm) were also removed.

At intermediate-depth stations (59 and 66 m), hydroids

were present May through December. Based upon the

presence of newly set juveniles, it appears that Anomia

squamula set only during that period as well. Very small

numbers of recently metamorphosed X. atlantica were

found throughout the year in every panel, with the ex-

ception of a single panel submerged May through Oc-

tober, 1978 when water temperatures were at a low of

5 to 9 °C. Panels submerged in subsequent years over-

lapped this period and showed settlement. At the deep

station (234 m) the only fouling organism was X. atlan-

tica. Both large and newly metamorphosed specimens

Page 22

THE NAUTILUS, Vol. 101, No. 1

Table 3. Wood-boring mollusks collected during this study

along the continental shelf of the eastern I'liited States. Aster-

isk (*) indicates range extensions.

Pholadidae

Xylophaga atlantica Flich-

ards. 1942

Jouannetia qtiillingi Tur-

ner, 1955*

Xylopholas altenae Turner,

1972*

Martesia jragilis Wrrill

and Bush. 1890

Barnea truncata (Say,

1822)

Xylophaga species 1. Tur-

ner, nis.

Xylophaga species 2. Tur-

ner, ms

Xylophaga species 3. Tur-

ner, ms.

Xylophaga species 4. Tur-

ner, ms*

Teredinidae

Teredo navalis Linne,

1758

Bankia gouldi (Bartsch,

1908)

Bankia carinata {Gray,

1827)

Lyrodus floridanus

"(Bartsch, 1908)

Nototeredo kiioxi

(Bartsch, 1917)

Psiloteredo megotara

Hanley, 1848

Teredothyra matocotana

(Bartsch, 1927)

Teredora malleolus (Tur-

ton, 1822)

were removed from the panel, indicating settlement

throughout the period of submergence.

Southern Atlantic Region

(Three Stations, 44 to 86 m)

Tripods were deployed in the South Atlantic Bight over

an 11-month period in 1978. Recruitment at mid-shelf

depths (44 and 47 m) was distinctly different from re-

cruitment at the 86-m station. At the shallow stations

the wood borers of Xylophaga (Turner species 4) and

Bankia carinata (Gray, 1827) (table 3) bored into the

panels from April through mid-July when water tem-

peratures were appro.ximately 19 °C. No wood borers

appeared from mid-July through November. Barnacles,

Balanus amphitrite (Linne, 1767) and B. veniistus

(Linne, 1767), and the bivalves Hiatella arctica (Linne,

1767) and Chione cancellata (Linne, 1767) settled dur-

ing February to mid-April. From mid-April to July the

panel was covered with hydroids and barnacles. These

were also present from July to November, with addi-

tional settlement of C. cancellata and the serpulid worm

Serpula vermicularis (Liiuie, 1767). A panel placed at

the deep station near the edge of the shelf (86 m) from

July to December had little surface fouling, but was

infested with large wood borers {Xylophaga species 4),

Teredothyra matacatona (Bartsch, 1927), and Bankia

gouldi (Bartsch, 1908) (table 3), Water temperatures

50

40

ID

uj 30

CD

•=1

10

0

0 15 10 ■)! 20 « 36

0 N D

Figure 4. Percent of population of Xylophaga species with

gonads in stage 5 ripe condition and mean gonad inde.x for

the months the animals were collected. Monthly sample size is

given at the top ol the graph.

reached mean monthly values of 18.9 °C for July and a

high of 24.4 °C for November.

Wood-Boring Mollusks

From the total collection of wood samples provided by

the tripod deployments and by the U.S. National Marine

Fisheries Service, nine species of pholads (Pholadidae)

and eight species of shipworms (Teredinidae) were iden-

tified (table 3). Xylophaga atlantica was found only north

of Cape Hatteras and was the most common pholad in

northern areas. It was collected at depths of 42 to 234

m, but only settled on panels at stations deeper than 60

m on the Middle Atlantic Bight and on Georges Bank.

An undescribed species of Xylophaga (Turner species 4)

settled only at the South Atlantic Bight stations. Its dis-

tribution overlapped little with X. atlantica. Xylopholas

altenae, previously known from a few deep stations off

Florida (Turner, 1972a), was collected at both shallow

(41 m) and deep (360 m) USGS stations at 39°N, firmly

establishing this northern range extension. Only single

samples of the other pholads were collected.

Histological examination of the gonads of the pholads

indicated gonadal ripening during the spring and

spawning during summer and late fall (figure 4) when

bottom water temperatures exceeded 10 °C on the

Georges Bank. With a long planktonic stage predicted

(Culliney & Turner, 1976), the larvae would not be ex-

pected to settle and metamorphose until the fall and

winter.

Table 4-. Anomia size analysis from

data of Merrill (1962) and Merrill and Kdwards (1976),

Buoy

Location

Dates in field

Mean size (mm) of Anomia

Nantucket Lightship Buov

40°33'N, 69°28'\V

10/8/57-5/10/58

X = 4,7

4 Davis Shoals #1 Buov

40°57'N, 69°55'W

5/7/57-5/15/58

X = 9, 1

4 Davis Shoals U'2 Buoy

40°57'N, 69°55'W

5/15/58-11/10/58

X = 2.4

C. J. Berg, Jr. ct al., 1987

Page 23

DISCUSSION

The observed seasonal settlement of the key species

{Anomia squamula, Chirona hameri, and Xylophaga at-

lantica) is quite striking. There are only a few studies

in the literature that discuss seasonal settlement of these

organisms.

Seasonality of occurrence of Anomia squamala has

been reported. Lebour (1938) found A. squamula larvae

common in the plankton throughout the year off Eng-

land, but especially in earl> autumn. Jorgensen (1946)

stated that A. squamula spawn from July to September

off Denmark, but larvae were also noted in November

and December. Dons (1936; in Jorgensen, 1946) reports

attachment of young to occur only during 3 months in

southern Norway, with a peak in either August or Sep-

tember. Merrill (1962) and Merrill and Edwards (1976)

studied A. squamula settlement on surface buoys just

south of Georges Bank and found heavy settlement in

the autumn (table 4), as reported in this study. It ap-

pears, therefore, that throughout its distribution in

northern latitudes, A. squamula has greatest recruitment

during autumn and winter. Off New England, settle-

ment occurs both at the surface and at the bottom dur-

ing this time. Insufficient data are provided in the earlier

papers to correlate settlement with environmental fac-

tors such as water temperature.

We could find no reference to seasonality of spawning

and settlement of C. hameri, nor to other species of

barnacles on Georges Bank. Based on the data presented

here, settlement of C. hameri at the bottom on Georges

Bank appears restricted to a short period from late April

through Jul\ ,

Almost nothing is known about the life history and

reproductive biology of species of Xylophaga. Short-term

placement of panels has shown that settlement of X.

dorsalis occurs between December and April off Mill-

port, Scotland (Turner & Johnson, 1971), and that set-

tlement of A', washingtona occurs between November

and January off Oregon (Turner and Johnson, 1971) and

year-round in California (Haderlie, 1983). Although X.

atlantica has been reared to metamorphosis (Culliney &

Turner, 1976) little else is known concerning its repro-

ductive or general biology. Our work suggests spawning

occurs in summer and again in late fall for these pholads.

On Georges Bank, X. atlantica metamorphoses and bores

into wood primarily between September and February.

At the Mid-Atlantic site this occurs 2 months later (No-

vember through April) and again later at the Southern

Atlantic site (December through June). This reflects dif-

ferences in periods of peak water temperatures at these

three areas.

Turner (1955) reviewed the available information on

pholads and emphasized how little was known. Purchon

(1941) discussed the biology of X. dorsalis, including

descriptions of general anatomy and feeding. Tipper

(1968) was the first to study the ecology of deep-sea

wood borers. He found X. washingtona in panels set at

depths of 200, 500, and 1,000 m on the continental ter-

race off Oregon. In general, the number of X. washing-

tona per square centimeter decreased with increasing

depth, and increased over time. The teredinid Bankia

setacea was also present in his collecting panels set at

200 m, but he did not recover them from shallower

depths, and attributed this to seasonal patterns of repro-

duction and coastal upwelling. Haderlie (1983) found

the overlap in B. setacea and X. washingtona to occur

only between 35 and 70 m in Monterey Bay, California.

Below that, X. washingtona was the only wood borer

present and settled during all months of the year. Water

temperatures at 70 m averaged 10 °C and were only

slightly colder at deeper sites.

DePalma (1963), in a series of tests conducted off

Florida, also documented an overlap in bathymetric

ranges of teredinids [Bankia carinata) and pholads (Xy-

lophaga sp.) Bankia carinata was found in test panels

set as deep as 165 m, but only in low numbers. Pholads

were common in panels set at 90 m, but none were

found at depths less than 30 m (Turner, 1966). In recent

tests, DePalma obtained Teredothyra matacotana in

wood set at 200 m, making this the deepest record for

teredinids invading new wood (Turner, personal obser-

vation). However, pholads invade the depths of the

oceans (Turner, 1972a,b, 1973a,b, 1981).

In the northwestern Atlantic, Teredo navalis and Xy-

lophaga atlantica exhibit overlapping bathymetric

ranges, with T. navalis extending from intertidal down

to 66 m and X. atlantica from 18 m (Turner & Johnson,

1971) to 234 m. In our study two minute teredinids were

collected with X. atlantica in a panel at 67 m on Georges

Bank and one T. navalis was collected among the X. at-

lantica at 60 m on Mid-Atlantic Station B. In the South

Atlantic Bight Xylophaga (Turner species 4) occurred

with Bankia carinata at 44 m and with Teredothyra

matacotana and Bankia gouldi at 86 m. These panels

were carried quickly to the bottom, and so could not

have become infested on the way down. Consequently,

the reported occurrence of these borers indicates their

true bathymetric range. Wood collected from the bot-

tom by the National Marine Fisheries Service was prob-

ably infested with teredinids at the surface or while

slowly sinking from the surface, and cannot be used to

describe bathymetric distributions.

Some planktonic larvae of marine invertebrates live

in the water column for extended periods of time before

they settle to the bottom and metamorphose into juve-

nile benthic forms. During their planktonic stage they

serve as food for other pelagic organisms, especially fish.

Alteration of the marine environment by outer conti-

nental shelf exploratory drilling and production might

have long-term effects upon phytoplankton production,

zooplankton production (including larvae), and fish pro-

duction. The use of wood panels to measure recruitment

might be used to measure some of these perturbations,

although the variability observed in this study and the

difficulty in separating larval availabilit) and observed

recruitment suggests that interpretation of such simple

monitoring studies would be difficult. Seasonal patterns

Page 24

THE NALTILL'S, Vol. 101, No. 1

of larval recruitment might be better defined and cor-

related to physical parameters (water temperature, cur-

rents, etc. ) if panels were deployed for short periods in

overlapping succession.

ACKNOWLEDGEMENTS

We thank Nancy Adams, Donald Flescher, and the staffs

of the Woods Hole branches of the U.S. Geological Sur-

vey and the National Marine Fisheries Service for help

in collecting and processing samples. The biological pro-

gram was supported b\' new initiative funds from the

Woods Hole Oceanographic Institution Sea Grant Pro-

gram (04-8-M01-149), and ONR contract NOOO 14-76-

C-0281, NR 104-687 with Harvard University. The

bottom tripod observations were supported by the U.S.

Geological Survey and the U.S. Bureau of Land Man-

agement through Memoranda of Understanding AA551-

MU8-24, AA551-MU9-4, AA551-MU0-18, AA551-MU8-

21, AA551-MU8-13, AA551-MU9-8, and Interagency

Agreement AA851-IA1-17.

LITERATURE CITED

Butman, B. and R. C. Beardsley. In press. Long-term obser-

vations on the southern flank of Georges Bank; Part I.

Seasonal cycle of current, temperature, stratification and

wind stress. Journal of Physical Oceanography.

Butman, B. and D. W. Folger. 1979. An instrument system

for long-term sediment transport studies on the continen-

tal shelf. Journal of Geophysical Research 84:1215-1220.

Culliney, J. L. and R. D. Turner. 1976. Larval development

of the deep-water wood boring bivalve, Xylophaga atlan-

tica Richards (Mollusca, Bivalvia, Pholadidae) Ophelia 15:

149-161.

DePalma, J. R. 1963. Marine boring and fouling organisms

off Fort Lauderdale, Florida. U.S. Naval Oceanographic

Office. Marine Sciences Department, hiformal Manu-

script No. 0-70-62a, 27 p.

Haderlie, E. C. 1983, Depth distribution and settlement times

of the molluscan wood borers Bankia setacea (Tryon, 1863)

and Xylophaga washingtona Bartscli, 1921, in Monterey

Bay. The VeUger 25:339-342, 2 pis.

Jergensen, C B. 1946. Lamellibranchia. Meddelelser Kom-

missionen Danmarks Fiskeri- og Havunders0gelser, Serie

Plankton 4:277-311.

Lebour, M. V. 1938. Notes on the breeding of some laniel-

libranchs from Plymouth and their larvae. Journal of the

Marine Biological Association of the L'nited Kingdom 23:

119-144.

Merrill, A. S. 1962. Variation and change in surface sculpture

in Anomia acoleata. The Nautilus 75:131-138

Merrill, A S. and R L. Edwards. 1976. Observations on

mollusks from a navigation buoy with special emphasis

on the sea scallop Placopecten magellanicus. The Nauti-

lus 90:54-61.

Purchon, R, D. 1941. On the biology and relationships of the

lamellibranch Xylophaga dorsalis (Turton). Journal of the

Marine Biological Association of the United Kingdom 25:

1-39.

Tipper, R. C. 1968. Ecological aspects of two wood-boring

molluscs from the continental terrace off Oregon. Doc-

toral dissertation, Oregon State Universit) , Corvallis, OR,

137 p.

Turner, R. D. 1955, The family Pholadidae in the western

Atlantic and the eastern Pacific. Part II — Martesiinae,

Jouannetiinae, and Xvlophaginae. Johnsonia 3:65-160, pis.

35-93.

Turner, R. D. 1966. Implications of recent research in the

Teredinidae. Beihefte zu Material und Organismen, Ber-

lin, Heft 1:437-446.

Turner, R. D. 1972a, A new genus and species of deep-water

wood-boring bivalves (Mollusca, Pholadidae, Xylophag-

ainae). Basteria 36:97-104.

Turner, R. D. 1972b. Xyloredo, a new teredinid-like abyssal

wood-borer (Mollusca, Pholadidae, Xylophagainae). Bre-

viora 397:1-19, pis. 1-6.

Turner, R, D, 1973a, Deep water wood-boring mollusks. Pro-

ceedings of the Third International Congress on Marine

Corrosion and Fouling, National Bureau of Standards,

Gaithersburg. Mar\land, p. 836-841.

Turner, R. D 1973b. Wood-boring bivalves, opportunistic

species in the deep sea. Science 180:1377-1379.

Turner, R. D. 1981. "Wood islands" and "thermal vents"

as centers of diverse communities in the deep sea Biolo-

giya Morya 1:3-10.

Turner, R. D. and A. C. Johnson. 1971. Biology of wood-

boring molluscs. In: Jones, E. B. G, and S. K. Eltringham

(eds.). Marine borers, fungi and fouling organisms of wood.

Organisation for Economic Co-operation and Develop-

ment, Paris, p. 259-301.

THE NAUTILUS 101(l);25-32, 1987

Page 25

North American Hydrobiidae (Gastropoda: Rissoacea):

Redescription and Systematic Relationships of

Tryonia Stimpson, 1865 and Pyrgtdopsis Call and Pilsbry, 1886

Robert Hershler

Department of Invertebrate Zoology

National Museum of Natural History

Smithsonian Institution

Washington, DC: 20560, USA

Fred C. Thompson

Florida State Museum

University of Florida

Gainesvilie, FL 32611, USA

ABSTRACT

Anatomical details are provided for the type species of Tryonia

Stimpson, 1865, Ptjrgulopsis Call and Pilsbry, 1886, Fonteli-

cella Gregg and Taylor, 1965, and Microamnicola Gregg and

Ta\ lor, 1965, in an effort to resolve the systematic relationships

of these taxa, which represent most of the generic-level groups

of Hydrobiidae in southwestern North America. Based on these

and other data presented either herein or in the literature,

Hyalopyrgus Thompson, 1968 is assigned to Tryonia, and

Fontelicella. Microamnicola, Natricola Gregg and Taylor, 1965,

Marstonia F. C, Baker, 1926, and Mexistiobia Hershler, 1985

are allocated to Pyrgulopsis.

The ranges of both Tryonia and Pyrgulopsis include parts

of eastern and western America and northern Mexico. Tryonia

is closely related to a group of North and Central American

littoridinine genera having an elongate-conic shell and (mam-

miform) glandular penial lobes, and Pyrgulopsis (Nympho-

philinae) is closely allied to Cincinnatia Pilsbry, 1891 from

eastern North America.

INTRODUCTION

Prosobranch snails of the family Hydrobiidae comprise

a major faunal element of North American freshwaters,

numbering some 28 genera and 148 species (Burch,

1982). Despite their diversity and ubiquity. North

American Hydrobiidae are poorly understood in terms

of systematics, as the anatomy of few species is known.

While recent advances have been made in the system-

atic study of southeastern Hydrobiidae (Thompson, 1968,

1969, 1977, 1984; Thompson & McCaleb, 1978), the fau-

na of other large expanses of territory is virtually un-

studied.

One such fauna is that of the arid Southwest. Of the

generic-group taxa found in this region, onK Flurijini-

cola Stimpson, 1865 has received sufficient morpholog-

ical study to allow clarification of its relationships

(Thompson, 1984). Relatively little is known of Pyrgu-

lopsis Call and Pilsbry, 1886, Tryonia Stimpson, 1865,

and Fontelicella Gregg and Taylor, 1965, the latter two

of which comprise more than 30 species (mostK unde-

scribed) in the Southwest. Taylor (1966) placed Tryonia

in the Littoridininae Taylor, 1966 on the basis of its

turreted shell and glandular penial lobes. It is clear from

the initial descriptions and subsequent studies illustrat-

ing the penis (Russell, 1971: fig. 4; Taylor, 1983:16-25)

that Fontelicella and its subgenera, Natricola Gregg and

Taylor, 1965 and Microamnicola Gregg and Taylor, 1965

belong to the Nymphophilinae Taylor, 1966 (see

Thompson, 1979). While the type species of Pyrgulop-

sis, P. nevadensis (Stearns, 1883), has not received an-

atomical study, the penes of several eastern species have

been examined b\' Thompson (1977), who suggested that

the genus may be a nymphophiline. The scant published

morphological data do not, however, allow meaningful

comparisons of the above with other Hydrobiidae.

Our anatomical study of the type species of Tryonia

and Hyalopyrgus Thompson, 1968 showed that Hyalo-

pyrgus, endemic to Florida (and placed in the Littori-

dininae by Davis et al., 1982), should be allocated to

Tryonia. Similarly, study of type species and published

accounts indicated that Fontelicella, Natricola, Mi-

croamnicola, as well as Mexistiobia Hershler, 1985 (from

northern Mexico) and Marstonia F. C. Baker, 1926

(widespread in eastern North America) should be allo-

cated to Pyrgulopsis. In this paper we redescribe Tryon-

ia and Pyrgulopsis and briefly discuss their affinities.

MATERIALS AND METHODS

Anatomical illustrations given in this paper are based on

study of the following lots (representing fully relaxed

alcohol material unless otherwise indicated): Tryonia

clathrata Stimpson, 1865, Moapa Springs, Clark County,

NV, USA, USNM 850291; Hyalopyrgus aequicostatus

(Pilsbry, 1889), Lake Dora, Lake County, FL, USA,

USNM 847212; Alexander Springs, Lake County, FL,

USA, UF uncatalogued lot; Pyrgulopsis nevadensis, re-

hydrated (in Bouin's solution) bodies, south end of Pyr-

amid Lake, Washoe County, NV, LISA, UF uncata-

logued lot; Pijrgulopsis archimedis S. S. Berry, 1947,

unrela.xed. Upper Klamath Lake, Klamath County, OR,

Page 26

THE NAUTILUS, Vol. 101, No. 1

Figure 1. Photograph (SEM) of holotype of Tryonia claihrata

Stimpson, Colorado Desert, CA, USA (but see Taylor, 1966:

197), ANSP 27969. Shell height is 4.36 mm. Figure 2. Close-

up photograph of shell of Tryonia dathrata Stimpson, Moapa

Springs, Clark County, NV, USA, USNM 850291, showing

sculptural pattern. The height of the portion of shell photo-

graphed is 2.36 mm. Figure 3. Photograph of shell of Tryon-

ia aequicostata (Pilsbry), Lake Dora, Lake County, FL, USA,

USNM 847212, printed to same enlargement as figure 1. Fig-

ure 4. Photograph of paratype of Pyrgulopsis nevadensis,

south end of Pyramid Lake, Washoe County, NV, USA, USNM

75450, printed to same enlargement as figure 1 Figure 5.

Photograph of shell of Pyrgulopsis lustrica (Pilsbrv), Little

Lakes. Herkimer County, NY, USA, USNM 28085, printed to

same enlargement as figure 1. Figure 6. Photograph of para-

type of Pyrgulopsis californiensis (Gregg and Taylor), Campo

Creek, San Diego County, CA, USA, USNM 850292, printed

to same enlargement as figure 1. Figure 7. Photograph of

shell of Pyrgulopsis micrococcus (Pilsbry), Springdale Springs,

Nye County, NV, USA, USNM 850297, printed to same en-

largement as figure 1. Figure 8. Photograph of shell of Pyr-

gulopsis manantiali (Hershler), spring at Tierra Blanca, SW

of Cuatro Cienegas, Coahuila, MEX, ANSP A9888L, printed

to same enlargement as figure 1.

Figure 9. Photograph (SEM) of central radular teeth of

Tryonia aequicostata (Pilsbry), Lake Dora, Lake County, FL,

USA, USNM 847212. Scale bar equals 10 ^m. Figure 10.

Photograph of protoconch of Tryonia aequicostata (Pilsbrv)

(from same lot as above). Scale bar equals 150 nm. Figure

11. Photograph of central radular teeth of Tryonia dathrata

Stimpson, Moapa Springs, Clark County, NV, USA, USNM

850291. Scale bar equals 10 fim. Figure 12. Photograph of

protoconch of Tryonia dathrata Stimpson (from same lot as

above). Scale bar equals 150 nm.

1985, small spring at Tierra Blanca, SW of Cuatro Cie-

negas, Coahuila, ME.X, ANSP A98881.

Snails were dissected in dilute Bouin's solution at 50 x

using a Wild M-8 dissecting microscope. Ciliation pat-

terns on the cephalic tentacles and penis were examined

using a Hitachi S-570 scanning electron microscope, with

the animals having first been graded into 100% ETOH

and dried using a Denton DCP-1 Critical Point Drier.

Shells and radulae were cleaned with Clorox and then

photographed using the scanning electron microscope.

USA, ANSP A602b; Pyrgulopsis letsoni (Walker, 1901),

creek W of Crenshaw Lake, Oakland County, MI, USA,

UF 91726; Pyrgulopsis scalariformis (Wolf, 1869), Mer-

amec River, 12.0 km SE of Leesburg, Crawford County,

MO, USA, UF 91727. Fontelicella (sensu stricto) cali-

forniensis Gregg and Taylor, 1965, Campo Creek, San

Diego County, CA, USA, USNM 850292 (paratypes);

Fontelicella (Microamnicola) micrococcus (Pilsbry in

Stearns, 1893), Springdale Springs, Nye County, NV,

USA, USNM 850297; Mexistiohia manantiali Hershler,

SYSTEMATICS

Genus Tryonia Stimpson, 1865

Tryonia Stimpson, 1865:54. Type species: Tryonia dathrata

Stimpson, 1865:54, by original designation; 1865:54.

Hyalopyrgus Thompson, 1968:43. Type species: Bythinella

aequicostata Pilsbr\, 1889:86, by original designation;

Thompson, 1968:45.

Diagnosis: Shell (figures 1-3) colorless, transparent,

elongate-conic to turreted, 1.7-7.0 mm tall with 4.0-8.0

R. Hershler and F. G. Thompson, 1987

Page 27

Figure 13. Photograph (SEM) of left tentacle of Tryonia clathrata Stimpson, Moapa Springs, Clark County, NV, USA, USNM

850291, showing ciliary tracts. Scale bar equals 176 ^ni. Figure 14. Photograph of right tentacle of Tryonia clathrata Stimpson

(from same lot as above). Scale bar equals 170 /um. Figure 15. Close-up photograph of ciliary tracts on right tentacle of Tryonia

clathrata Stimpson (same specimen as above). Scale bar equals 30 ^m. Figure 16. Photograph of left tentacle of Tryonia

aequicostata (Pilsbry), Alexander Springs, Lake County, FL, USA, UF uncatalogued lot. Scale bar equals 176 ixm. Figure 17.

Photograph of right tentacle of Tryonia aequicostata (Pilsbry) (from same lot as above). Scale bar equals 200 nm. Figure 18.

Photograph of penial tip of Tryonia clathrata. Moapa Springs, Clark County, NEV, USA, USNM 850291, showing sparse ciliation,

terminal papilla, and blunt swelling on inner (left) side. Scale bar equals 50 ^ni.

whorls; typically high-spired with rounded whorls and

indented sutures. Aperture simple, unthickened, and

complete. Umbilicus narrow or absent. Sexual dimor-

phism pronounced, with males often half of female shell

height. Protoconch (figures 10, 12) flat or slightlv pro-

truding, smooth or slightly wrinkled. Teleoconch sculp-

ture consisting of fine growth lines, sometimes coupled

with weak spiral lines or collabral striations or varices.

Central tooth of radula (figures 9, 11) broader than tall,

with 1-3 pairs of basal cusps. Digestive gland without

anterior lobe. Cephalic tentacles with several elongate

ciliary tracts (figures 13-17). Flattened penis (figures 19,

20) elongate and slender, with a single, enlarged glan-

dular (mammiform) lobe at its base and 1-4 smaller

glandular lobes on the inner curvature. Distal portion of

penis ciliated (figure 18) to varying degrees, base some-

times also ciliated. Tip of penis with blunt swelling on

inner curvature. Females ovoviviparous, with 3-15 em-

bryos brooded in enlarged capsule gland (figure 21).

Capsule gland with muscular sphincter at anterior end.

Pallial oviduct reflected posteriorly, albumen gland re-

duced in size (figure 22, Ag). Small-sized bursa copula-

trix and seminal receptacle ventral to albumen gland;

coiled seminal receptacle duct opens into short sper-

mathecal duct (figures 23, 24, Osr).

Species included: Bijthinella aequicostata; Bythinella

brevissima Pilsbry, 1890:64; Potamopyrgus cheatumi

Page 28

THE NAUTILUS, Vol. 101, No. 1

0.75 mm

Figure 19. Penis of Tnjonia clathrala Stimpson, Moapa Springs, Clark County, NV, USA, USNM 850291- Figure 20. Penis of

Tnjonia aequicostata (Pilsbry), Alexander Springs, Lake County, PL, USA, UF uncatalogued lot. Patterns of ciliation are not

shown. Flo = penial lobe.

Pilsbry, 1935:91; Calipyrgula circumstriata Leonard and

Ho, 1960a:125; Tnjonia clathrata; Paludestrina diaboli

Pilsbry and Ferriss, 1906:125; Paludestrina imitator

Pilsbry, 1899:121; Calipyrgula pecosensis Leonard and

Ho, 1960b:110; Amnicola protea Gould, 1855:129; Pa-

ludestrina stokesi Arnold, 1903:22.

The identity of the Central and South American taxa

assigned to Tryonia by Taylor (1966) is uncertain due

to lack of anatomical study.

Distribution: Tryonia occurs in much of Florida as well

as in the arid Southwest, including parts of California,

Figure 2L Tryonia clathrala Stimpson (without shell), Moa-

pa Springs, Clark C:ounty, NV, USA, I'SNM S.50291. viewed

from the right side. Note the enlarged capsule gland (C^g) with

embryos (dotted circles). The thickened dots on the digestive

gland (Dg) are pigment granules. C;g = capsule gland, Ct =

ctenidium, Dg = digestive gland, Edg = posterior end of diges-

tive gland. In = intestine, Ki = kidney. Op = operculum, Pc =

pericardium, St = stomach.

Nevada, Arizona, New Mexico, and Texas, and northern

Mexico.

Remarks: Given the overall similarity between the Flo-

ridian and southwestern species, even extending to de-

tails of the bursa copulatrix complex (figures 23, 24),

there can be no doubt that these species belong to a

single genus. Tryonia belongs to a group of littoridinines

having an elongate-conic shell and mammiform glan-

dular lobes on the penis that includes Aphaostracan

Thompson, 1968, Littoridinops Pilsbry, 1952, Mexipyr-

gus Taylor, 1966, and Pyrgophorus Ancey, 1888 (but

not Durangonella Morrison, 1945; contrar\- to Hershler,

1985). Tryonia is distinguished from the above by its

turreted shell and unique position of its penial lobes.

Genus Pyrgulopsis Call and Pilsbry, 1886

Pyrgiilopsis Call and Pilsbry, 1886:9. Type species: Ptjrgiila

i\evadetisis Stearns, 1883:173, bv original designation; Call

and Pilsbry, 1886:9.

Marstonia F. C. Baker, 1926:195. Type species: Amnicola lus-

trica Pilsbry, 189053, bv original designation; F. C. Ba-

ker, 1926:195.

Fontelicella Gregg and Taylor, 1965:103. Type species: Fon-

telicrlla californiensis Gregg and Ta\lor, 1965:109, by

original designation; Gregg and Ta\lor, 1965:104.

Natricola C-regg and Taylor, 1965:108. T>pe species: Pomal-

iopsis rohusta Walker, 1908:97, b\ original designation;

Gregg and Taylor, 1965:109

Microamnicola Gregg and Taylor, 1965:109. Type species:

Amnicola micrococcus Pilsbry in Stearns, 1893:277, by

original designation; Gregg and Taylor, 1965:109.

R. Hershler and F. G. Thompson, 1987

Page 29

Sts

Osd

0.5 mm

Figure 22. Posterior portion of pallial oviduct and associated organs and structures of T. clathrata Stimpson, Moapa Springs,

Clark County, NV, USA, USNM 850291, viewed from the right. Note the posterior reflection of the palhal oviduct and small

albumen gland (Ag). The thickened curving Hne indicates the posterior end of the pallial cavity \g = albumen gland, Bu = bursa

copulalri.x, Cg = capsule gland. In = intestine, Oes = oesophagus, Osd = opening of the spermathecal duct, Ov = oviduct, Pc =

pericardium, Sd = spermathecal duct, Sts = style sac. Figure 23. Bursa copulatrix complex of Tnjonia clathrata (from same lot

as above), with the bursa removed (position indicated by dashed lines) in order to reveal the underlying structures. The visceral

ganglion connective (Cvg) is tightly pressed against the oviduct. Bu = bursa copulatrix, Cvg = visceral ganglion connective, Oov =

opening of oviduct into albumen gland, Ov = oviduct, Osr = opening of seminal receptacle into spermathecal duct, Sd =

spermathecal duct, Sr = seminal receptacle. Figure 24. Bursa copulatrix complex of Tnjonia aequicostata (Pilsbry), Alexander

Springs, Lake County, FL, USA, UF uncatalogued lot. The thickened curving line indicates the posterior end of the pallial cavity.

Bu = bursa copulatrix, Cvg = visceral ganglion connective, Oov = opening of oviduct into albumen gland, Osr = opening of

seminal receptacle into spermathecal duct, Sd = spermathecal duct, Sr = seminal receptacle.

Mexistiobia Hershler, 1985:46. Type species; Mexistiobia

manantiali Hershler, 1985:47, by original designation;

Hershler, 1985:46,

Diagnosis: Shell (figures 4-8) globose to elongate-conic,

1.2-8.0 mm in height, with 3.0-6.0 whorls. Aperture

simple, sometimes loosened from body whorl. Umbilicus

absent to open. Protoconch partly or totally covered with

wrinkled pits (Thompson, 1977: fig. 4; Hershler, 1985:

fig. 11). Teleoconch smooth or unicarinate on periphery

(figure 3), usually with fine growth lines. Radula (figures

25-28) typically taenioglossate, with basal cusps on the

central teeth. Mantle and/or penial filament (figures 29,

30, 32, 33) often with distinctive pigment markings. Pe-

nis (figures 29-33) with small, distal lobe and narrow,

elongate filament. Penial surface with one to fifteen

glandular ridges, sometimes on stalked crests. Females

oviparous; capsule gland with two tissue sections and a

near-terminal opening (figures 34, 35; Thompson, 1977:

figs. 5, 7, 10, 11, 18; Hershler, 1985: fig. 14). Oviduct

with a single anterior coil on the left side of the albumen

gland into which opens the seminal receptacle. Bursa

copulatrix typically enlarged and partly posterior to al-

bumen gland; bursa duct and oviduct jointly open into

anterior portion of albumen gland.

Species included: Marstonia agarhecta Thompson,

1969:243; Pyrgulopsis archimedis S. S. Berry, 1947:76;

Fontelicella californiensis; Marstonia castor Thomp-

son, 1977:130; Amnicola deserta Pilsbry, 1916:111;

Marstonia halcyon Thompson, 1977:128; Amnicola

hendersoni Pilsbry, 1933:10; Amnicola idahoensis Pils-

bry, 1933:11; Pomatiopsis intermedia Tryon, 1865:220;

Amnicola letsoni Walker, 1901:113; Amnicola longin-

qua Gould, 1855:130; Amnicola lustrica; Mexistiobia

manantiali; Amnicola micrococcus; Amnicola neomex-

Page 30

THE NAUTILUS, Vol. 101, No. 1

Figure 25. Photograph (SE\4) of central radular teeth of Pyr-

gulopsis nevadensis (Stearns), Pyramid Lake. Washoe County,

NV, USA, UF uncatalogued lot. Scale bar equals 12.0 ftm.

Figure 26. Photograph of lateral teeth of Pyrgttlopsis neva-

densis (Stearns). Scale bar equals 12.0 fim. Figure 27. Pho-

tograph of inner marginal tooth of Pyrgulopsis nevadensis

(Stearns). Scale bar equals 8.6 ^ni. Figure 28. Photograph

of outer marginal tooth of Pyrgulopsis nevadensis (Stearns).

Scale bar equals 7.5 nm.

icana Pilsbry, 1916:111; Marstonia ogmorphaphe

Thompson, 1977:120; Amnicola olivacea Pilsbry, 1895:

115; Pyrgulopsis ozarhensis Hinkley, 1915:588; Mar-

stonia pachyta Thompson, 1977:121; Amnicola pilsbfiji

Baily and Bally, 1952:50; Pomatiopsis rohusta Walker,

1908:97; Ptjrgula scalariformis Wolf, 1869:198; Palii-

destrina stearnsiana Pilsbry, 1899:124; Pyrgulopsis wa-

bashensis Hinkley, 1908:117.

Fossil species assigned to Marstonia and Fontelicella

by Taylor (1960) and Gregg and Taylor (1965) are not

included.

Distribution: Pyrgulopsis occurs in much of eastern

North America as well as throughout western North

America and parts of northern Mexico.

Remarks: Only a limited anatomical study could be

made of Ptjrgulopsis nevadensis, the type species of

Pyrgulopsis, as only dried bodies were available. We

were able to describe its radula (figures 25-28) and penis

(figure 29). The species has long been considered en-

dangered (Taylor, 1970) and may now be e.xtinct in the

sole locality from which living material was ever found.

Pyramid Lake. A recent limnological survey of this lo-

Figure 29. Penis of Pyrgulopsis nevadensis (Stearns), south

end of Pyramid Lake, Washoe County, NV, USA, UF uncat-

alogued lot. The dorsal aspect is shown to the left and ventral

aspect is on the right. The screened areas indicate glandular

ridges whereas the darkened areas are pigmented. Figure 30.

Penis of Pyrgulopsis letsoni (Walker), creek W of Crenshaw

Lake, Oakland County, MI, USA, UF 91726. Figure 31. Pe-

nis of Pyrgulopsis scalariformis (Wolf), Meramec River, 12,0

km SE of Leesburg, Crawford County, MO, USA, UF 91727.

Figure 32. Penis of Pyrgulopsis californiensis (Gregg and

Taylor), Campo Creek, San Diego County, CA, USA, USNM

850292, Plo = penial lobe, Vd = vas deferens. Figure 33.

Penis of Pijrgulopsis micrococcus (Pilsbrv), Springdale Springs,

Nye County, NV, USA, USNM 850297.'

cality yielded no live individuals (Galat ct al.. 1981) of

this species, nor were they found during a recent trip to

the lake by one of us (F.G.T.).

It is clear from our study that the sole character dis-

tinguishing species assigned to Pyrgulopsis and other

taxa that we consider congeneric is the presence of a

peripheral carina on the shell. Pyrgulopsis is noteworthy

tor its diversity in shell and penial morphology. Even

within small regions in the .Southwest, groups of species

show gradations from globose to elongate-conic shells,

or gradations from a simple penis with few ridges to a

more complex penis with accessory crests and numerous

ridges. The eastern species previously assigned to Mar-

stonia and Pyrgulopsis. united by possession of a penis

having few glandular ridges and a broad penial lobe

(Berry, 1943: fig. 6; Thompson, 1977: figs. 5, 7, 11, 13,

19, 22, 24), clearly intergrade with western species as-

signed to Pyrgulopsis, Fontelicella sensu stricto and Mi-

croamnicola. We have no doubt that Pomatiopsis ro-

Imsta, the type species of Natricola, is also a Pyrgulopsis,

based on anatomical data given by Gregg and Taylor

R. Hershler and F. G. Thompson, 1987

Page 31

Dbu

Figure 34. Left lateral aspect of the paUial oviduct and bursa

copulatrix complex of Pyrgiilopsis californiensis (Gregg and

Taylor), Campo Creek, San Diego County, CA, USA, USNM

850292. The two tissue sections of the capsule gland (Cg) are

indicated by the stippled areas. The thickened curving line

indicates the posterior end of the pallial cavity. Ag = albumen

gland, Bu = bursa copulatrix, Cg = capsule gland, Cga =

capsule gland opening, Dbu = duct of the bursa copulatrix,

Sr = seminal receptacle. Figure 35. Left aspect of the pallial

oviduct and bursa copulatrix complex of Pyrgiilopsis archi-

medis S. S. Berry, L'pper Klamath Lake, Klamath County, OR,

USA, ANSP A662B.

(1965:108). The unique, stunted appearance of the bursa

copulatrix complex of P. manantiali (Hershler, 1985:

fig. 14) is probably a result of the extremely minute size

of the snail. In other features such as shell form and

penial morphology the species clearly conforms to the

Pyrgulopsis groundplan.

Among nymphophilines that have received anatomi-

cal study, Pyrgulopsis is most similar to Cincinnatia

Pilsbry, 1891, which has a somewhat larger and broader

shell as well as a more complex penis having a very small

filament, a large number of glandular ridges, and nu-

merous accessory crests (Thompson, 1968: figs. 43-47;

Davis & Mazurkiewicz, 1985: figs. 11-15).

ACKNOWLEDGEMENTS

Drs. G. M. Davis (ANSP), A. Bogan (ANSP), and W, L.

Pratt (Museum of Natural History, University of Nevada

at Las Vegas), as well as J. J. Landye (Arizona Game

and Fish) and K. Auffenberg (Florida State Museum,

University of Florida) loaned material necessary for the

completion of this report. Mrs. M. Ryan assisted with

the preparation of the illustrations. We thank two anon-

ymous reviewers for their useful criticisms.

LITERATURE CITED

Ancey, C, F. 1888. Etude monographique sur le genre Pyr-

gulopsis. Bulletins de la Societe Malacologique de France

5:185-202.

Arnold, R. 1903. The paleontology and stratigraphy of the

marine Pliocene and Pleistocene of San Pedro, California.

Memoirs of the California Academy of Sciences 31-420

Baily, J. L. and R. I. Baily. 1951-52. Further observations

on the Mollusca of the relict lakes in the Great Basin. The

Nautilus 65:46-53, 85-93.

Baker, F. C. 1926. Nomenclatural notes on .American fresh

water mollusks. Transactions of the Wisconsin Academy

of Science, Arts, and Letters 22: 193-205.

Berry, E. G. 1943. The .\mnicolidae of Michigan: distribution,

ecology, and taxonomy. Miscellaneous Publications of the

Museum of Zoology, University of Michigan 57:1-68.

Berry, S. S. 1947. A new Pyrgulopsis from Oregon. The Nau-

tilus 60:76-78.

Burch, J. B. 1982. Freshwater snails (Mollusca: Gastropoda)

of North .f^merica. U.S. Environmental Protection .Agen-

cy, Contract No. 68-03-1280, EPA-600/3-82-026, 294 p.

Call, R. E. and H. A Pilsbry 1886. On Pyrgulopsis. a new-

genus of rissoid mollusk, with descriptions of two new

forms. Proceedings of the Davenport Academy of Natural

Sciences 5:9-14.

Davis, G. M. and M, Mazurkiewicz. 1985. Systematics of

Cincinnatia winkleyi (Gastropoda: Hydrobiidae). Pro-

ceedings of the Academv of Natural Sciences of Phila-

delphia 137:28-47.

Davis, G. M., M. Mazurkiewicz, and M. Mandracchia. 1982.

Spurwinkia: morphology, ssstematics, and ecology of a

new genus of North American marshland H\drobiidae

(Mollusca: Gastropoda). Proceedings of the Academy of

Natural Sciences of Philadelphia 134:14.3-177.

Galat, D. L., E. L. Lider, S. Vigg, and S. R Robertson. 1981.

Limnology of a large, deep North American terminal lake.

Pyramid Lake, Nevada, U.S. Hydrobiologia 82:281-317.

Gould, A. A. 1855. New species of land and freshwater shells

from western (N.) America, Proceedings of the Boston

Society of Natural History 5:127-130.

Gregg, VV.'\'. and D. W. Taylor. 1965. Fontelicella (Proso-

branchia: Hydrobiidae), a new genus of West American

freshwater snails. Malacologia 3:103-110.

Hershler, R. 1985. Systematic revision of the Hydrobiidae

(Gastropoda: Rissoacea) of the Cuatro Cienegas Basin,

Coahuila, Mexico. Malacologia 26:31-123.

Hinklev, A. A. 1908. A new species of Pyrgulopsis. The Nau-

tilus 21:117-118.

Hinklev, .A. ■\. 1915. New fresh-water shells from the Ozark

Mountains. Proceedings of the United States National Mu-

seum 49:587-589.

Leonard, A. B. and T.-Y. Ho. 1960a, New Calipyrgula from

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THE NAUTILUS, Vol. 101, No. 1

Pleistocene of Texas and notes on Cochhopa riogranden-

sis. The Nautilus 73:125-129.

Leonard, A. B. and T.-Y. Ho. 1960b. A new species of Cal-

ipyrgula (H\drobiidae) from the Pleistocene of Texas. The

Nautilus 73!ll0-113.

Morrison, J. P. E. 1945. Durangonella, a new hydrobiine

genus from Mexico, with three new species. The Nautilus

59:18-23.

Pilsbry, H. A. 1889. New and little known American mol-

lusks. No 1. Proceedings of the Academy of Natural Sci-

ences of Philadelphia 41:81-89.

Pilsbry, H. A. 1890. Notices of new Amnicolidae The Nau-

tilus 4:63-64.

Pilsbry, H. A. 1895. New American freshwater mollusks. The

Nautilus 8:114-116.

Pilsbry, H. A. 1899. Catalogue of the Amnicolidae of the

western United States. The Nautilus 12:121-127.

Pilsbry, H. A. 1916. New species of Amnicola from New

Mexico and Utah. The Nautilus 29:111-112.

Pilsbry, H. A. 1933. .*\mnicolidae from Wyoming and Ore-

gon. The Nautilus 47:9-12,

Pilsbry, H. A. 1935. Western and southwestern Amnicolidae

and a new Huniboldtiana. The Nautilus 48:91-94.

Pilsbry, H. A. 1952. Littoridina leniiipes (Couper). The Nau-

tilus 66:50-54,

Pilsbry, H. A. and J. H. Ferriss. 1906. Mollusca of the south-

western states. II. Proceedings of the Academy of Natural

Sciences of Philadelphia 58:123-175.

Russell, R. H. 1971. Mollusca of Fish Springs, Juab County,

Utah: rediscovery of Stagnicola pilshryi (Hemphill, 1890).

Great Basin Naturalist 31:223-236,

Stearns, R, E, C, 1883, Description of a new hydrobiinoid

gasteropod from the mountain lakes of the Sierra Nevada,

with remarks on allied species and the physiographic fea-

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Stearns, R, E. C, 1893, Report on the land and fresh-water

shells collected in California and Nevada by the Death

Valley Expedition, including a few additional species ob-

tained by Dr C, Hart Merriam and assistants in parts of

the southwestern United States, North .American Fauna

7:269-283.

Stimpson, W. 1865. Researches upon the Hydrobiinae and

allied forms. Smithsonian Miscellaneous Collections 201:

1-59.

Taylor, D. W. 1960. Late Cenozoic molluscan faunas from

the High Plains. U.S. Geological Survey Professional Pa-

pers 337:1-94.

Taylor, D. W. 1966. A remarkable snail fauna from Coa-

huila, Mexico. The Veliger 9:152-228,

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Clarke, A. H. (ed.). Proceedings of the American Malaco-

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to the New Mexico Department of Game and Fish, Con-

tract Nos. 519-69-01, 519-69-OlA, 81 p.

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drobiidae of peninsular Florida, University of Florida Press,

Gainesville, FL, xv -I- 268 p.

Thompson, F G, 1969. Some h>drobiid snails from Georgia

and Florida, Quarterlv Journal of the Florida .\cademy

of Science 32:242-265',

Thompson, F. G, 1977. The hydrobiid snail genus Marstonia.

Bulletin of the Florida State Museum, Biological Sciences

21:113-158.

Thompson, F, G, 1979, The systematic relationships of the

hvdrobiid snail genus Nymphophilu.s Ta\lor 1966 and the

status of the subfamily Nymphophilinae, Malacological

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genera of the hydrobiid subfamily Lithoglyphinae. Mal-

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snail from a spring in eastern Alabama. .American Mid-

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Tryon, G. W. 1865. Descriptions of new species of Amniro/a,

Pomatiopsis, Somatogyrus. Cahbia, Hydrobia, and Ris-

soa. Journal of Conchology 1:219-222.

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American Journal of Conchology 5:198.

THE NAUTILUS 101(1)33-44, 1987

Page 33

Ecological Differentiation Within the Genus Helisoma

(Gastropoda: Planorbidae) in Central Canada

Eva Pip

Department of Biology

University of Winnipeg

Winnipeg, Manitoba R3B 2E9

Canada

ABSTRACT

The distributions of Helisoma anceps. H. campanulatum. H.

corpulentum. H. pilslnyi infracarinatum. and H. trivolvis were

examined in relation to water body and substrate type, eight

water chemistry parameters, Helisoma species diversity (HSD),

total gastropod diversity (TGD), and macrophyte diversity

(MD). A total of 310 of the 437 sites studied contained Heli-

soma. Significant interspecific differences existed with respect

to the most frequented types of water bodies and substrates,

as well as with respect to ecological tolerance ranges for total

dissolved solids, total alkalinity, phosphorus, nitrate, sulphate,

dissolved organic matter, and chloride. These differences were

reflected in the geographical distributions of the species. Hel-

isoma trivolvis was the most widespread species within the

study area, and showed the broadest ecological tolerance ranges

for the parameters examined, while H campanulatum was

the most restricted in terms of habitat parameters, and was

found primarily on the Precambrian Shield, Helisoma anceps

occupied an intermediate position between these two species.

Helisoma corpulentum and H. p. infracarinatum were rare

in the study area. Geographical range extensions are presented

for H. a. royalense, H. corpulentum. and H. campanulatum.

Multiple regression analysis showed that sulphate, dissolved

organic matter, and chloride together accounted for ca. 10%

of the variability in HSD. HSD was positively correlated with

TGD and MD. Significant interspecific differences existed with

respect to HSD and MD, but not TGD, Ecological differences

between species of the same genus may reduce competition

where geographical ranges overlap and may be an important

factor in divergent evolution.

INTRODUCTION

The geographical boundaries of the distributions of sev-

eral planorbid species are located in central Canada, an

area which also contains a number of important geologic

interfaces. The genus Helisoma is of particular interest,

since in this region it is represented by all five species

[as currently understood (e.g., Clarke, 1981)] native to

Canada: H. anceps Menke, 1830, H. campanulatum Say,

1821, H. corpulentum Say, 1824, H. pilsbryi Baker, 1926,

and H. trivolvis Say, 1816.

Although the ranges of these species overlap in central

Canada, preliminary observations have suggested that

often only one or two species of this genus may be pres-

ent in any given habitat. It was therefore the objective

of the present study to determine whether the latter

suspicion was indeed true, and if so, whether the distri-

butions of individual species could be differentiated with

respect to common habitat descriptors such as water body

type, bottom substrate, and water chemistry. The ecol-

ogy of Helisoma species is thus far known primarily in

qualitative terms (e.g.. Baker, 1932, 1936, 1945; Clarke.

1973, 1981); some quantitative data have been reported

for the study area by Pip (1978, 1985, 1986).

THE STUDY AREA

The present study was carried out within the area

bounded by 47° and 54°N, and 94° and 106°W. This

region is geologically diverse. The Precambrian Shield,

which consists largely of granitic and gneissic volcanic

rock, dominates the eastern portion of the study area

east of Lake Winnipeg. The area west of Lake Winnipeg

and including much of Lakes Winnipegosis and Mani-

toba is underlain mainly by Ordovician, Silurian, and

Devonian sedimentary rocks, particularly limestone and

dolomite. West of the latter two lakes these sedimentary

rocks are of more recent Triassic and Cretaceous origin.

Irregular deposits of Cenozoic shales occur in the south-

western portion of the study area. The waters of the

Precambrian Shield are typically low in dissolved inor-

ganic materials (Pip, 1985), but west of the Shield

boundary, total alkalinity and dissolved solids tend to

show higher values.

MATERIALS AND METHODS

A total of 437 sites was examined within the study area

during the May-September seasons of 1972-85. Of these,

41% were lakes (> 10 ha), 42% ponds (< 10 ha), 9%

rivers ( > 2 m deep), and 8% creeks ( < 2 m deep).

Because of environmental heterogeneity, large lakes were

sampled at a number of different stations, which were

each treated as separate sites. All sites contained water

year-round.

While heterogeneous substrate types were present at

Page 34

THE NAUTILUS, Vol. 101, No. 1

54 "N

48'N

I02«W

94°*

Figure 1. Distribution of sites where H trivolvis was record-

ed.

many sites, habitats were classified according to the pre-

dominant substrates present where the snails were found.

Approximately 11% of the water bodies sampled had

primarily granitic bedrock bottom, 2% limestone bed-

rock, 1% shale, 16% a mixture of gravel and coarse sand,

27% sand, 6% silt, 19% clay, and 18% mainly organic

substrates such as peat.

Shallow sites were examined for the presence of mol-

luscs and aquatic macrophytes by wading, while deeper

waters were sampled by dredging with a rake from a

small boat, or, at depths of > 3 m, by using SCUBA.

Search time at each site was limited to 1 hr. Plant ma-

terial was taken to the laboratory, washed, and exam-

ined for additional snails. Only macrophytes that were

at least partially submerged were scored. Diversity was

defined as the number of species present.

Surface water samples were collected for most sites,

although at depths of > 3 m a van Dorn sampler was

used. The samples were placed on ice in darkness and

frozen within a maximum of 48 hr. Samples were ana-

lyzed using methods recommended by the American

Public Health Association (1971). The pH was measured

in situ with a portable pH meter.

While most sites were visited only once, approxi-

mately 50 locations were resampled at different times

of the season and in different years. For these sites, ex-

treme low and high water chemistry parameter values

were used for statistical analysis. The critical signifi-

• H. ANCEPS ANCEPS

*« ANCEPS ROYALENSE

• HPILSBRYI

INFRACARINATUM

94° W

Figure 2. Distribution of sites where H. anceps and H. pils-

briji infracarinatum were recorded.

cance level for all statistical procedures in the present

study was p = 0.05.

RESULTS

Distribution

Of the 437 cases examined, 310 contained a record of

one or more Helisoma species. Helisoma trivolvis was

the most frequently observed member of this genus and

was widely distributed throughout the study region (fig-

ure 1), occurring at approximately 44% of the sites vis-

ited. Clarke (1981) recognized two subspecies of H. tri-

volvis in the area under consideration: H. t. trivolvis east

of Manitoba (except for a small region in central Sas-

katchewan) and H. t. subcrenatum Carpenter, 1856 in

Manitoba and to the west. In the present study this zoo-

geographical separation was not found to be quite as

distinct; both forms occurred in southern Manitoba, al-

though H. t. subcrenatum was much more common.

These two forms are usually distinguished by differences

in axial height (Clarke, 1981), but large series examined

at certain sites {e.g., Jackson Lake, near Sidney in south-

western Manitoba) showed a wide range of this char-

acter, suggesting that further study is needed regarding

the status of these two forms.

Helisoma anceps was also widely distributed in the

study area, although it was less common in the south-

western portion (figure 2). It was found at 24% of the

sites sampled. While H. a. anceps formed the majority

E. Pip, 1987

Page 35

of the occurrences of this species, two populations of H.

a. royalense Walker, 1909 were found in eastern Man-

itoba (West Hawk Lake in Whiteshell Provincial Park

and Bird Lake in Nopiming Provincial Park), repre-

senting a westward range extension for this taxon from

its previously known boundary in northwestern Ontario.

Helisoma campanidatum (figure 3) was distributed

primarily on the Precambrian Shield. Occurrences west

of the Shield were sporadic, but these constituted south-

westward extensions of the range reported by Clarke

(1981). The bulk of the populations encountered con-

sisted of H. c. campanidatum, although a few occur-

rences of H. c. coUinsi Baker, 1939 were noted in the

southeastern portion of the study area. This species

showed a wide range of morphology and size at different

sites.

Helisoma pilsbryi infracarinatum Baker, 1932 was

infrequently found in the present study (4% of sites sam-

pled). It was not seen in the southwestern portion of the

study area (figure 2).

Helisoma corptdentum was very rare in the study

area and was found at only 1% of the sites visited. It

was found at a few stations on the Winnipeg River in

southeastern Manitoba, and in Whitefish Lake, located

on the Manitoba-Saskatchewan border in the Porcupine

Provincial Forest, approximately 400 km west of its

nearest Winnipeg River occurrence, thus constituting a

range extension (figure 3). The Whitefish Lake locus, so

far as is known, was not linked by intervening occur-

rences to the Winnipeg River populations and may pos-

sibly have been the result of accidental transport by

human agency, since this lake is frequented by tourist

sport fishermen. However, H, corpulentum was com-

mon in the lake and therefore must have existed there

for some time.

Community Diversity

The mean number of Helisoma species (HSD) found at

the same site was lowest for sites containing H. trivolvis

and highest for sites where H. pilsbryi infracarinatum

was observed (table 1). HSD was compared for the four

most frequent species; one-way analysis of variance was

used, since Cochran's C and Bartlett-Box F tests indicat-

ed that the homogeneity of variance assumption re-

quired for this test was valid. The F ratio between the

54°N

100 km

•H. CAMPANULATUM

■ H. CORPULENTUM

'iB'U

102° W

94" W

Figure 3. Distribution of sites where H. campanidatum and

H. corpulentum were recorded.

species was highly significant (table 2), suggesting that

the respective species differed in their tendency to occur

in communities where other members of the genus were

present. Different species pairs were further examined

using Duncan's, Student-Newman-Keuls, Tukey's "hon-

estly significant difference, " and Scheffe's multiple com-

parison procedures (Winer, 1971). The results (table 2)

showed that H. trivolvis and H. p. infracarinatum each

differed from the other three species with respect to

HSD.

When the four species were compared with respect

to the total numbers of gastropod species recorded at

each site (TGD), there were no significant differences

between them (table 2). However, comparisons of aquatic

Table 1. Mean HSD, TGD, and VID values for sites where each Helisoma species occurred. Values in parentheses are standard

errors

Page 36

THE NAUTILUS, Vol. 101, No. 1

Table 2. Results of one-way analysis of variance and species-pair comparisons with respect to coinmunit\ diversit\ for the four

most frequent species.

Diversit) parameter

Significance of F ratio

among four species

Species pairs significantK (p < 0.05) different

No. of Helisoma spp. at

same site (HSD)

Total gastropod diversity

at same site (TGD)

Macrophyte diversit) at

same site (MD)

F = 11.6

p < 0.001*

2.03

0.11

F

P

F = 20.1

p < 0,001*

H. trivolvis vs. H. campanulattim' -•'^■■'

H. trivolvis vs. H. anceps' -

H. trivolvis vs. H. p. infracarinatum^-'^''

H. p. infracarinatum vs. H. ancpp.s' - '^

H. p. infracarinatum vs. H. campanulatum'^^-^'*

None

H. campanulatum vs. H. anceps^''-^*

H campanulatum vs. H trivolvi.s^-^''

II campanulatum vs. H p. infracarinatum' -

' Duncan.

- Student-New man-Keuls.

^ Tukey "honestly significant difference'

' Scheffe.

* Significant difference.

macrophyte species richness (MD) yielded a highly sig-

nificant F ratio that was largely attributed to differences

between H. campanulatum and the other three species

(table 2).

HSD was highly significantly correlated with TGD

(r = 0.56, p < 0.001, N = 430) and with MD (r = 0.32,

p < 0.001, N = 430) recorded at the same sites. TGD

and MD were also correlated with each other (r = 0.26,

p < 0.001, N = 430).

Chi-square tests were applied to determine whether

any of the species appeared to be associated with others.

The results (table 3) showed that most species pairs were

not significantly associated. Only two significant positive

associations were found: H. trivolvis with H. pilsbryi in-

fracarinatum, and H. campanulatum with H. corpu-

lenturn. In both cases the second species was rare. Thus

the three most common species did not tend to occur

with each other at the same site, suggesting that they

frequented different habitats within the study area. Be-

cause of the low frequencies of H. p. infracarinatum

and H. corpulentum. these taxa were excluded from

further analysis; what is known of their habitat charac-

teristics within the study area has been summarized by

Pip (1986).

Water Body and Substrate Type

The distributions of the three common species were ex-

amined with respect to water body type by using 2 x

4 chi-square tests to compare the number of occurrences

in each of the four cells for sites where each species was

present and those where it appeared to be absent. These

groups are henceforth designated as "found sites and

"remaining " sites, respectively. "Remaining" sites were

used for comparison rather than the overall site sam-

pling distribution because the more frequently a species

occurs, the more its distribution pattern approaches that

of the overall sampling distribution. In the study area

both H. anceps and H. campanulatum showed signifi-

cantly different distributions at found sites compared to

the remaining sites (figure 4). Helisoma anceps was

moderately and H. campanulatum strongly more fre-

quent in lakes than would be expected from the sam-

pling distribution. Helisoma campanulatum also oc-

curred the most frequently of the three species in rivers,

but was not found in creeks. Helisoma anceps occurred

less frequentK in lotic waters. Helisoma trivolvis did

not appear to show any distinct preference with respect

to water body type.

Table .3. Results of chi-square tests for interspecific association. Upper diagonal = chi-square, lower diagonal = p N = 437

H. trivolvis

H.p.

H. anceps H. campanulatum infracarinatum II. corpulentum

* Significant positive correlation.

E. Pip, 1987

Page

WATER BODY TYPE

SUBSTRATE TYPE

<

o

o

I-

z

UJ

o

cr.

50

40

30

20

10

A

H. ANCEPS

IN' 106 50-1 N-308

p<0.04 20 -^H

I 2^ B^^^

H. CAMPANULATUM

H. TRIVOLVIS

N« 189

|X^'I.82

P'0.61

N.S.

I« LAKES, >I0 ho

2" PONDS, < 10 ho

3« RIVERS, >2 m deep

4= CREEKS, <2 m deep

301

20

10

H. ANCEPS

N- 107

X - 13.1 p<0.04

30

20-

10-

N'30l

12345678 B| 2 34567 8

50

40

30-

20-

10

H. CAMPANULATUM

1 N* 73 ■

N'335

X ' 32 5

p-<i;o.ooi

30

20

10

2 3 4 5 6 7 8

301

20

10

A

H. TRIVOLVIS

N-189

1= GRANITIC BEDROCK

2- LIMESTONE BEDROCK

3« SHALE

4- GRAVEL/COARSE SAND

5- SAND

6- SILT

7- CLAY

8« ORGANIC SUBSTRATE

Figure 4. Comparisons of sampling distributions for water body type and bottom substrate type of found (A) and remaining (B)

sites for the three most frequent species. Horizontal brackets indicate the cells that were combined for chi-square anahsis for all

species. N.S. = no significant difference.

Further comparisons were made among species by

using chi-square tests for each possible species pair (table

4). Helisoma campanulatum differed highly signifi-

cantly in distribution from both H. anceps and H. tri-

volvis; it was primarily a lacustrine species and seldom

occurred in ponds. The latter two species each occurred

with appro.ximately equal frequencies in lakes and ponds.

Helisoma anceps and H. trivolvis did not differ signif-

icantly from each other.

Distribution with respect to predominant substrate

type was compared at found vs. remaining sites using

2x6 chi-square tests (figure 4). Substrate type was di-

vided into six cells; limestone and shale categories were

combined in order to raise the theoretical frequencies

and to avoid zero column sums in the contingency ta-

bles. All three species showed significantly different dis-

tributions at found sites compared to remaining sites,

and also when compared to each other (table 4). Heli-

soma campanulatum showed a strong preference for

sand. Helisoma trivolvis tended to be more frequent on

clay, and H. anceps on highly organic substrates com-

pared to remaining site frequencies.

Water Chemistry

Distributions of water chemistry parameters were first

examined using preliminary chi-square tests. Extreme

low and high parameter values were included for sites

Page 38

THE NAUTILUS, Vol. 101, No. 1

Table 4. Results of species-pair clii-square comparisons with

respect to water body aiui bottom substrate t\ pe for the three

most frequent species. I'pper diagonal = chi-square, lower

diagonal = p

H. H.

trivolvis anceps

H.

campanu-

latum

A. Water bod> type

H. trivolms x 3.02 50.7

H. anceps 0 61 x 46 4

H. campanulatiirn < 0 001* < 0.001* x

Overall chi-square = 57.5, p < 0,001*

B. Bottom substrate type

H. trivolvis x 14.4 36.5

H. anceps 0.03* x 20.5

H. cnmpanulatum < 0.001* < 0.001* x

Overall chi-square = 47 9, p < 0 001*

* Significant difference.

that were sampled a number of times. The distributions

were divided into six cells for all factors except chloride

and sulphate, which were assigned three and four cells,

respectively.

All three species showed significantly different distri-

butions for total dissolved solids at found sites compared

to remaining sites (figure 5). Helisonia campanulatum

showed the greatest affinity for low values, while H.

trivolvis appeared to tolerate the highest concentrations.

The differences between these two species can be seen

in the similarity of the distributions of the found sites

for H. trivolvis and the remaining sites for H. campan-

ulatum in figure 5. Total alkalinity showed trends sim-

ilar to those seen for total dissolved solids (figure 5).

Molybdenum reactive phosphorus was significantly

different at found and at remaining sites for all species

(figure 6). The greatest proportion of found sites in the

lowest concentration class was seen for H. anceps. How-

ever, H. campanulatum showed the lowest mean value

because H. anceps could also occur at sites with higher

values than the maximum seen for H. campanulatum.

Helisoma trivolvis showed the highest percentage of sites

with high values.

Significant differences for combined nitrate and ni-

trite were observed at found and at remaining sites only

for H. campanulatum and H. trivolvis (figure 6). Heli-

soma campanulatum showed the greatest frequencies

at the lower end of the concentration scale, while H.

trivolvis showed the greatest proportion of higher val-

ues.

The pH was significantly different at found and at

remaining sites only for H. campanulatum (figure 7),

which showed the narrowest range of values of the three

species. Chloride appeared to be important for H. cam-

panulatum (figure 7), which occurred exclusively at sites

with low values of this parameter. Chi-square values

were very small for the other two species.

Sulphate was a significant parameter for H. campan-

ulatum and H. trivolvis (figure 8). The former was lim-

ited (with one exception) to the lowest concentration

cell, while the latter tolerated a broad range of values.

Dissolved organic matter was significant for all species

Table 5. Results of Kruskal-Wallis one-way analysis of variance and species-pair comparisons with respect to water chemistry

parameters for the three most frequent species.

Parameter

Chi-square, corrected for ties

Species pairs significantly

different (p < 0,05)

pH

Total dissolved solids

Total alkalinity

Molybdenum reactive phosphorus

Nitrate and nitrite

(Chloride

Sulphate

Dissolved organic matter

0.38, p = 0.83

62.1, p < O.OOl'*

54.9, p < 0.001*

9.16, p = 0.01*

15.0. p < 0 001*

29.9, p < 0.001*

39.1, p < 0.001*

15.0, p < 0.001*

None

H. trivolvis vs

H. trivolvis vs

H. anceps vs.

H. trivolvis vs

H. trivolvis vs

H. anceps vs.

H. trivolvis vs

H. trivolvis vs

H. trivolvis vs

H. trivolvis vs

H. trivolvis vs

trivolvis vs

trivolvis vs

anceps vs.

trivolvis vs

trivolvis vs

. H. campanulatum'-

. H. anceps'-^*

H. campanulatum'

. H. campanulatum'-''

. H. ancep.t''-^^

H. campanulatum' -•'

. H. campanulaliun''-

. H. anceps' -'

. H. campanulatum'-

. H. anceps' -^

. H. campanulatum' -

. H. campanulatum''

. H. anceps' -■^''

H. campanulatum'

. H. campanulatum' '

. H. anceps'"

' Duncan,

* Student- Newman- Keuls.

' Tukey "honestly significant difference'

■' Scheffe.

* Significant difference.

E. Pip, 1987

Page 39

B

<

H

O

UJ

B

TOTAL DISSOLVED SOLIDS, mg I'

H. ANCEPS

p<.OI

o 5

o

rj tM .^ CA A ^ tt

O O o o o o o

o o o o o o o

o o

o o

o o

o o

o o

H- CAMPANULATUM

t ■ 104

N • 90

X* ■ 62.7

p <<*:.ooi

fo (ji X. ui ^ •^ a x;=Noi*u>

OOoOOOoSqOoOO

ooooooog8g§go

X • 382

o o o o o 6 o

o o o o o

0'^^^^^t^<^<y^-^<3>— — fout^^ <T>

oOoooooqOJJoooo

"ooooooo 2S oooo

o O o o o o

40 -W

30-^^

B 20-^^L

267

246

I I I

XOoOOOOQ

°OoOOOOO

ro oj .tt

^ ^ o o o

°o §§§

o o

01

o

o

o

B

TOTAL ALKALINITY, mg T' CaCO,

40

30

A to

10

30

20

10

50

40

A 30

20

10

H. ANCEPS

;• Its

N- 114

X- 16.9

P<.OI

= Soo<oo«pwo&owowo

OO^QOOOOOOoOoOO

S Q «

; • 124

N • 336

owoSoSoSowowo-

o o

OB

w o

k

OOOOOOOoOOOO

H. CAMPANULATUM

i* 71

N> 91

X • 90. 1

p <a;.ooi

Figure 5. Comparisons of sampling distributions for total dissolved solids and total alkalinit\ of found {.\) and remaining (B) sites

for the three most frequent species. Horizontal brackets indicate the cells that were combined for chi-square analysis for all species

at found us. remaining sites (figure 8). As had been seen

for total dissolved solids, again the distribution of re-

maining sites for H. campanulatum resembled the dis-

tribution of found sites for H. trivolvis.

The water chemistry parameters were examined fur-

ther for interspecific differences among the three most

frequent species. Since several water chemistry param-

eters did not show normal sampling distributions, non-

parametric multiple comparisons were made for all

parameters using Kruskal-Wallis one-way analysis of

variance. The results indicated that all parameters ex-

cept pH showed significant interspecific differences (ta-

ble 5). Each species pair was then compared using Dun-

can's, Student-Newman-Keuls, Tukey's "honestly

significant difference," and Scheffe s multiple compari-

son tests. The results showed significant pair differences

for all variables except pH (table .5). Helisoma trivolvis

differed significantly from H. campanulatttm and from

H. anceps with respect to total dissolved solids, total

alkalinity, phosphorus, combined nitrate and nitrite, sul-

phate, and dissolved organic matter. Helisoma trivolvis

also differed from H. campanulatum with respect to

chloride. Helisoma anceps differed from H. campanu-

latum with respect to fewer chemical parameters; these

were: total alkalinity (most significant) and, at reduced

levels of significance, total dissolved solids and sulphate.

Page 40

THE NAUTILUS, Vol. 101, No. 1

MOLYBDENUM REACTIVE PHOSPHORUS, mg

^O"^ H. ANCEPS

30-H

X" 2.5 X ■ 13.7

N- 116 p <0.02

<

O

LlI

o

a:

UJ

. F^. V

oiO»oiji6oibb<bi» 5

H. CAMPANULATUU

20-^ X ■ 2.2 X'- 18.7

A in-^^^^H N-94 p<O.OI

B

30

20

10

30

A 20

10

I I I 1 I I I I I 1 1 ■ I 1 f rr-Ti

o — — MM oio<**.w«a»-^oo= 5;V

''°'*6bibo>bbiO« w

u

i • 2.2

N- 353

Or-— mmwo<**«««>-JOBq ijV

<*°'*bbiboio<J>bw oi

k.

H. TRIVOLVIS

i • 3.6

N ■ 197

X ■ 16.1

p <0.0I

P--r-MMOI W4>4k(* Oi<»)--J0B55y

""-'''bbibbiocxow u

30

A 20

10

B

50

40

30

20

10

30

A 20

10

40

30

20

10

NITRATE*NITRITE, mg I"

— :- M M

bbiboib«Ooi

I I I — I— r

Or-— mmo'><'**«o"

wO'^bixboibo'

T — r I I

ffi <j> r-J N

di b in O t»

%

H. CAUPANULATUM

i =■ 0.8 X*' 35.8

N"9I p<t:o.ooi

Or-f-MMo<o(**oiwo>0)r<J

UO«boib6ib<J«bi»b6iO

Ul

I I I I I I r-^"

p— :-MMOIol**OlWffi01N

(«o»buibo<buibu<boiO

(II

TPIVOLVIS

1.3 X*' 25.5

197 p < 0.001

X •

N'

P r- — M M W OI

W O OI ■

^ I I — r— I-

* .» ex m 91 9> N

bwooibwbu'ouio

0.9

253

I I I I I t — I I I

p — — MMO<}«**««0)0>S-~J

oiO«»baiOoiboiOoib6iObi

Figure 6. CJomparisons of sampling distributions for moK bdenum reactive phosphorus and combined nitrate and nitrite of found

(A) and remaining (B) sites for the three most frequent species. Horizontal brackets indicate the cells that were combined for chi-

square analysis for all species. N.S. = no significant difference.

The relative importance of the different water chem-

istry parameters could not be defined, since the latter

showed a high degree of intercorrelation (table 6). HSD

was significantly inversely correlated with dissolved or-

ganic matter, total dissolved solids, chloride, and total

alkalinity (table 6). Stepwise multiple regression of un-

transformed water chemistry parameters on HSD as the

dependent variable admitted two parameters into the

regression equation, which together accounted for only

4% of the observed variability in HSD: dissolved organic

matter (R- = 0.03 after step 1) and chloride (R- = 0.04

after step 2) (p = 0.0001, N = 479). Respective beta

values were —0.17 and —0.12, indicating that dissolved

organic matter was more important.

When HSD and the chemical parameters (e.xcept pH)

were log transformed, correlation with total dissolved

solids improved substantially when compared with the

corresponding values for untransformed variables (table

6), and new significant inverse correlations emerged for

sulphate and combined nitrate and nitrite. Apparently

these relationships were nonlinear. Stepwise multiple

regression of untransformed variables (except pH) ad-

mitted sulphate alone into the equation (R- = 0.05, p =

0.020, N = 479).

DISCUSSION

The results of the present study suggested that the three

most common Helisoma species coexist within the study

area by frequenting habitats with somewhat different

physical and chemical characteristics. Within the study

area the major factors that differed between H. trivolvis

E. Pip, 1987

Page 41

PH

o

30-1 ;. 8.0

10

10

10

Figure 7. Comparisons of sampling distributions for pH and chloride of found (A) and remaining (B) sites for the three most

frequent species. Horizontal brackets indicate the cells that were combined for chi-square analysis for all species. N.S. = no

significant difference.

and H. campanulatum were: habitat type, substrate type,

total dissolved solids, total alkalinity, phosphorus, ni-

trate/nitrite, sulphate, chloride, and dissolved organic

matter. Helisoma trivolvis differed from H. anceps with

respect to fewer factors; these were: substrate type, total

dissolved solids, total alkalinity, phosphorus, nitrate/ni-

trite, and sulphate. Helisoma campanulatum and H.

anceps differed with respect to the fewest factors: hab-

itat type, substrate type, total alkalinity, total dissolved

solids, and sulphate. In addition, H. campanulatum

tended to occupy habitats that had a much higher

macrophyte species richness than those frequented by

other species. These observations explained to a large

extent the geographical distributions of these species.

Helisoma campanulatum, with its significant prefer-

ence for lakes and rivers, sand substrates, low water

chemistry parameter values, and high macrophyte di-

versity, was found mainly on the Precambrian Shield,

where such habitat characteristics were common. Heli-

soma anceps, with less stringent requirements, occupied

a correspondingly broader area. Its significant but re-

duced preference for lakes (compared to H. campanu-

latum), decreased frequency in lotic waters, and greater

tolerance of rather higher water chemistry parameter

values was reflected in its greater frequencies in waters

west of the Shield, even though it was still much more

common in Shield waters, where low parameter values

predominated.

Because of the reduced number of low-value water

chemistry parameter sites west of the Shield, H. anceps

and H. campanulatum often occurred together at these

sites, and therefore appeared to be associated when a

subset of data containing a high proportion of non-Shield

sites was considered (Pip, 1978). However, such associ-

ation was not apparent on the Shield (Pip, 1985).

Helisoma trivolvis showed the widest tolerance ranges

for water chemistry values and could occupy all water

body and bottom substrate types. The broader variety

Page 42

THE NAUTILUS, Vol. 101, No. 1

DISSOLVED ORGANIC MATTER, A

UJ

o

cm

LJ

a.

279 nm

30

A 20

10

fc

O OOOOOOO — .— :- — .-ro

X • 0.37

N • 336

P ppooopp — — — — —

r^ <jt t, iji ot -A (D o to *' 9t at

ppppoopp.— — —

— rv)oiik6i<J>-^ooP'^*>

TRIVOLVIS

p <0.0I

p p O O O P P

NOI*o<b)^<DP'*'*"bD

X- 0.35

N" 232

ppopoop— — .—

9* QB

IM

b

Figure 8. Comparisons of sampling distributions for dissolved

for the three most frequent species. Horizontal brackets indicate

N.S. = no significant difference.

organic matter and sulphate of found (A) and remaining (B) sites

the cells that were combined for chi-square analysis for all species.

of habitats that were tolerated by this species was re-

flected in its comprehensive spatial distribution within

the study area. Although it could exist in the Shield-type

oligotrophic waters for which H. campanulatum was

specialized, it could also easily occupy the alkaline and

eutrophic habitats that were common in the southwest-

ern portion of the study area and which were beyond

the tolerance range limits of the other two species.

Hetisonia trivolvis showed the smallest mean HSD

value. Thus, if only one Helisoma species was present

at a site, it was most likely to be H. trivolvis. This sug-

gested that it may have been a good colonizer of habitats

too severe for the other species, and/or it may have

showed a lower rate of extinction, since it would be more

likely to survive when environmental fluctuations ex-

ceeded the tolerance ranges of the other species.

The negative correlations observed between HSD and

several water chemistry parameters, notably sulphate and

dissolved organic matter, were due to the fact that all

five species could occup\ habitats with low water chem-

istry parameter values, but as the latter increased, pro-

gressively fewer species could tolerate them. But, al-

though sulphate, dissolved organic matter, and chloride

appeared to be significant, they explained onl\ one-tenth

of the variability of HSD. Clearly other environmental

factors, as well as elements such as chance associated

with dispersal, colonization, and extinction (e.g., Aho,

1978), played important roles.

While many sites could accommodate more than one

Helisoma species, such instances arose in habitats whose

environmental properties fell in the regions of overlap

between the tolerance ranges of the different species.

■\lthougli none of the three most frequent species were

positively associated with each other, neither did any

' Significant correlation.

species exclude any other, since none were negatively

correlated. The lack of significant correlation as a con-

sequence of the observed differences in types of habitats

frequented by the respective species may enhance the

survival of these species by reducing interspecific com-

petition. The habitats containing the greatest numbers

of Helisoma species in the present study were typically

highly productive sites that were also diverse in terms

of other gastropods and aquatic macrophytes. A greater

variety of microhabitats was available at such sites, al-

lowing for possible niche partitioning of the type de-

scribed, for example, by Pip and Stewart (1976).

It should be pointed out that, although the tolerance

ranges and other characteristics of the species have been

examined here for the study area as a whole, individual

species may show some regional differences, depending

on environmental characteristics. For example Pip (1985)

reported that H. campanulatum tended to show a nar-

rower ecological tolerance range for total dissolved solids

that was concentrated towards the lower end of the con-

centration scale when only Precambrian Shield sites were

considered, compared to the study area as a whole. Such

differences, which reflect local environmental condi-

tions, are apparently the result of adaptation.

While the present study was concerned largely with

ecological relationships within the genus Helisoma in

the study area, certain other gastropods as well as aquat-

ic macrophytes may be associated with individual species

of this genus. These have been reported elsewhere (Pip,

1978, 1985).

The status of the two rare species, H. corpulentum

and H. pihbryi infracarinatum, within the ecological

framework of the three common species is more difficult

to interpret. Both of these taxa appeared to be most

frequent in eastern portions of the study area, although

both also showed patchy occurrences west of the Shield.

From the few recorded cases available, H. corpulentum

appeared to be a species of oligotrophic waters, with

ecological tolerance ranges restricted to low water

chemistry parameter values. It was most similar in its

physical and chemical ecological attributes to H. cam-

panulatum, with which it was positively associated. Its

distribution and rarity are perplexing. In the eastern

portion of the study area it was apparently limited to

the Winnipeg River and was not found in the numerous

adjacent lakes and rivers in the region, even though water

chemistry parameters of many of these fell within the

observed tolerance ranges of this species. The supposi-

tion that it may dislike lacustrine habitats is invalidated

by its abundance in Whitefish Lake in western Mani-

toba.

Helisoma p. infracarinatum occurred more frequent-

ly than H. corpulentum. The observed ecological tol-

erance ranges for H. p. infracarinatum seemed to be

intermediate between those of H. campanulatum and

H. anceps for a number of water chemistry parameters

(see Pip, 1986). However, it is interesting that, despite

the ecological similarity of H. p. infracarinatum to the

latter two species, it was significantly associated with H.

trivolvis. This association was seen primarily in the east-

ern portion of the study area; it remained apparent when

a subset of exclusively Precambrian Shield sites was ex-

amined (Pip, 1985). In the study area as a whole, H.

trivolvis was present in > 85% of the cases where H. p.

infracarinatum was recorded.

The systematic relationship between H. trivolvis and

Page 44

THE NAUTILUS, Vol. 101, No. 1

H. p. infracarinatum is unclear. Previous workers {e.g..

Baker, 1928, 1936; Clarke, 1973) have remarked on the

problematic amount of variation in morphology of H.

p. infracarinatum. In the present study, many occur-

rences could be clearly assigned to either H. trivolvis or

H. p. infracarinatum, but at several sites both forms

were present together with intergrades. Baker (1928)

also reported such intergradation from Wisconsin. The

two ta.xa may possibly be more closely related than is

thought at present. One possibility, suggested by Clarke

(1973), is that, if the two taxa are interrelated, H. p.

infracarinatum might be a hybrid of H. trivolvis and

H. corpulentum, although it was much more common

in the present study area than H. corpulentum. This

could be explained by its wider ecological tolerance

ranges. Another possibility might be that it is indeed a

separate species, and the intergrades observed at some

sites may be hybrids between it and H. trivolvis. Heli-

soma p. infracarinatum might also be a genetic variant

of H. trivolvis; populations where the two forms appear

to be distinct could be examples of dimorphism. Since,

in the study area, H. p. infracarinatum showed a well-

defined range of ecological parameters within which it

occurred, it might be an ecophenotype of H. trivolvis,

manifested by certain genotypes in the population.

Whatever the explanation, it must account for the high

degree of association between the two taxa. Until more

studies are made, the status of H. p. infracarinatum

remains uncertain.

tance of chemical and spatial variables, Annales Zoologici

Fennici 15:155-164.

American Public Health Association. 1971. Standard meth-

ods for the examination of water and wastewater Amer-

ican Public Health Association, New York, 874 p.

Baker, F. C, 1928. The fresh water Moiiusca of Wisconsin.

Part I. Gastropoda. Bulletin No. 70, Wisconsin Geological

and Natural History Survey, Madison, Wisconsin, 507 p.

Baker, F. C. 1932. New species and varieties of Helisoma

and Gyraultis from Canada. The Nautilus 466-9.

Baker, F. C. 1936. The freshwater mollusc Helisoma cor-

pulentum and its relatives in Canada. Bulletin No. 79,

National Museum of Canada, p, 1-37,

Baker, F, C, 1945, The molluscan family Planorbidae. Uni-

versity of Illinois Press, Urbana, IL, 519 p.

Clarke, A. H. 1973. The freshwater molluscs of the Canadian

Interior Basin. Malacologia 13(l-2):l-509.

Clarke, A. H. 1981, The freshwater molluscs of Canada. Na-

tional Museum of Natural Sciences, Ottawa, Ontario, 446 p.

Pip, E. 1978. A survey of the ecology and composition of

submerged aquatic snail-plant communities. Canadian

Journal of Zoology 56:2263-2279,

Pip, E. 1985, The ecology of freshwater gastropods on the

southwestern edge of the Precambrian Shield. Canadian

Field-Naturalist 99:76-85,

Pip, E, 1986. The ecology of freshwater gastropods in the

central Canadian region. The Nautilus 100:56-66.

Pip, E, and J, M. Stewart. 1976. The dynamics of two aquatic

plant-snail associations. Canadian Journal of Zoologv 54:

1192-1205.

Winer, B. J. 1971. Statistical principles in experimental de-

sign McGraw-Hill, New York, 907 p.

LITERATURE CITED

Aho, J. 1978. Freshwater snail populations and the equilib-

rium theory ol island biogeography. II. Relative impor-

THE NAUTILUS 101(l):45-47, 1987

Page 45

The Publication Date of Solarium architae O. G. Costa

Kenneth J. Bos§

Arthur S. Merrill

Department of Molliisks

Museum of Comparative Zoology

Harvard Universitv

Cambridge, MA 02138. USA

Recent and current interest in the gastropod family Ar-

chitectonicidae continues unabated with revisions of

genera (Bieier, 1984a, 1985a,b, 1986), descriptions of

new species (Bieier, 1984b; Merrill & Boss, 1984; Bieier

et al., 1985), considerations of the radular apparatus

(Bandel, 1984; Boss & Merrill, 1984), the larval shell

(Scheltema & Williams, 1983; Bandel et al, 1984), and

the anatomy (Haszprunar. 1985a,b) as well as remarks

on the geological occurrences (Janssen, 1984; Moroni &

Ruggieri, 1984) and zoogeographical ranges (Emerson,

1983; Bieier, 1984a; Melone & Taviani, 1985).

It is troublesome to note that conflicting opinion char-

acterizes the citation of the original publication and date

of the binomen Solarium architae O. G. Costa, a species

of architectonicid. With a distribution in the Atlantic

Ocean and Mediterranean Sea (Merrill, 1970), this rea-

sonably common, off shore benthic species has been re-

centU placed in the genus Pscudotorinia (Bieier, 1985b;

Bieier et al., 1985). The type-specimen in the Zoological

Museum of the University of Naples was destroyed dur-

ing World War II (Bieier. 1985b; Melone & Taviani,

1985).

Dates given for the original introduction of this taxon

in the literature include 1830, 1831, 1839, 1841, 1843,

and 1844. These include, chronologically arranged: for

1830, Costa (1841), Aradas and Benoit (1870), Monter-

osato (1873), Jeff revs (1885), Locard (1886), Kobelt (1887),

Marshall (1887), Watson (1897), Locard (1899), Tomlin

and Shackleford (1914), Bayer (1948), Marche-Marchad

(1969), Merrill (1970), Turolla (1974), Piani (1980), Ter-

reni (1981), Micali and Giovine (1983), Boss and Merrill

(1984), and Bieier (1985b); for 1831, Ghisotti (1974); for

1839, Ghisotti (1976), Ghisotti and Turolla (1976). and

Melone and Taviani (1985); for 1841, Monterosato (1872),

Nobre (1938-40), Priolo (1955), and Bieier et al. (1985);

for 1843, Ghisotti (1974); and for 1844, Hanlev (1863),

Keen (1971), Abbott (1974), and Sherborn (1923).

The title of the publication in which the binomen

supposedly appeared for the first time also differs; Ca-

talogo de' Testacei viventi nel Golfo di Taranto (Costa,

1841), Catalogo dei Testacei viventi nel grande e pic-

colo mare di Taranto (Aradas & Benoit, 1870; Parenzan,

no date [post 1976]), Catalogo dei Testacei viventi nel

Goljo di Taranto (Turolla, 1974), Catalogo de Testacei

viventi nel Piccolo e Grande mare di Taranto (Ghisotti,

1974) and Catalogo sisteniatico dei Testacei viventi nel

mare di Taranto (Ghisotti, 1976).

There are even inconsistencies in quoting the original

Latin description (viz. Turolla, 1974; Ghisotti & Turolla,

1976).

Thus, the problem of properly citing this species is

compounded by conflicting opinion as to the date of

publication of the nomen and the title of the original

work in which it appeared; the rarity and obscurity of

the publications of O. G. Costa further e.xacerbate this

situation.

Oronzio-Gabriele Costa (1787-1867) published nu-

merous papers in conchology and paleontology, a partial

list of which was given b\' Ghisotti (1974). A more com-

plete listing is provided in the Catalogue of Scientific

Papers (1800-63), Vol. II, compiled and published by

the Royal Society of London (1868). A thorough search

of original sources shows that Solarium architae was first

described and figured in Costa's Fauna del Regno di

Napoli. Animali Molli. Classe III. Gasteropodi. Pettini-

branchi. p. 5, which was published Ma\ 12, 1841 (Sher-

born, 1910, 1937; Erasmo, 1949; Johnson, 1984). There-

in, Costa (1841:6) gave the following citation:

Solarium Architae, Costa, Catal. de' Test. viv. nel

Golfo di Taranto (Atti della R. Accad. delle Scienze

vol. \T [sic]. — Rapporto de' lavori della stessa pel

1830, p. 40, n. 15).

This referred to a paper that was in press or preparation

in the Atti and appeared as:

Costa, Oronzio-Gabriele 1844.

Catalogo de' testacei viventi nel piccolo e grande

mare di Taranto redatto sul sistema di Lamarck.

Atti della Reale Accademia delle Scienze, Sezione

della Societa Reale Borbonica, Vol. V, Parte II, pp.

13-66, pis. 1-4.

His comment, "Rapporto de lavori della stessa pel 1830,

p. 40, no. 15 [Report of the work of the same title for

1830] must have been construed by subsequent workers

as an actually published paper appearing in the Atti for

Page 46

THE NAUTILUS, Vol. 101, No. 1

1830. No such paper of that title appears in the Atti in

1830 or any year until 1844, nor were any recorded by

Sherborn (1922, 1932). This was confirmed b\ a search

of the Atti as well as by consulting the Indice gene-

rale del lavori pubhiicata dal MDCCXXXVII al

MDCCCCIII of the Reale Accademia Delle Scienze

Fisiche e Matematiche (Classe delta Societd Reale di

Napoli) which is an index of all published papers in the

variously titled series for those dates.

In the 1844 publication of Costa, "Solarium architae

nob." appears on p. 48 as the first species of Solarium

and no figure is included; this dating of the name was

cited in Sherborn (1923) and others as noted above.

Although a manuscript of the "Catalogo" or a pri-

vately printed paper by Costa may have circulated, much

like his rare zoological observations in the Pantellerian

Islands (Iredale, 1922), there is no indication of this being

the case and no such document has ever been located.

Furthermore, authors who cited the year 1830 as the

original date for the introduction of S. architae either

referred to the "Catalogo in one of its variant titles

and/or to the Atti, vol. 3, p. 40, no. 15, first so cited by

Monterosato (1873).

In summary. Solarium architae Costa, despite nu-

merous other datings in the literature, was first described

in 1841; the type-specimen is lost; the t\pe-locality is

the Gulf of Taranto and the type-figure is the original

Costa (1841), pi. 5, figs, a. A, B, C. The species is of

particular interest in having such a long lived larval

form that its distribution, like a number of teleplanic

architectonicids, is amphi-Atlantic.

ACKNOWLEDGEMENTS

We thank the librarians of the Museum of Comparative

Zoology, Harvard University, the Smithsonian Institu-

tion, the American Museum of Natural History, the

Academy of Natural Sciences of Philadelphia, the Bos-

ton Public Library, the New England Book Deposit Li-

brary, and the Library of the Rijksmuseum van Na-

tuurlijke Histoire in Leiden. Our colleagues, Dr. Riidiger

Bieler, Dr. William K. Emerson, Mr. Richard I. Johnson,

Dr. Graham Oliver, Dr. Robert Robertson, Dr. Joseph

Rosewater, and Dr. A. C. van Bruggen are personally to

be acknowledged. We especially thank Dr. R. Tucker

Abbott who, in a critical evaluation of the Bieler et al.

(1985) manuscript, called attention to a discrepancy of

Costa dates in that paper with the dates which appeared

in another recent paper by Boss and Merrill (1984).

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Bayer, C. 1948. Catalogue of the Solariidae in the Rijksmu-

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1: Pseudomalaxis. Archiv fiir Molluskenkunde 11.5(1/3);

53-103, 6 figs., 5 pis,

Bieler, Riidiger, 1984b, Heltacus oerdensis n.sp. von den

Kapverdischen Insein (Gastropoda: Architectonicidae).

Archiv fiir Molluskenkunde 115(1/3):105-111, 1 pi

Bieler, Riidiger 1985a, Die Gattungen der Architectonicidae

(Gastropoda: "Heterogastropoda"), Teil 2: Architectoni-

ca, Philippia, Dinaxis, Stellaxis. Discolectonica. Solati-

sonax, Climacopoma. Granosolarium. Archiv fiir Mollus-

kenkunde 115(4/6):231-265, 5 pis,

Bieler, Riidiger, 1985b. Die Gattungen der Architectonicidae

(Gastropoda: Allogastropoda), Teil 3: Pseiidotorinia. Sip-

teraxis, Heliacus, Eosolarium. Archiv, fiir Mollusken-

kunde 116(l/3):89-117, 7 figs., 4 pis.

Bieler, Riidiger. 1986. Revision of genera in Indo-Pacific

species in the family Architectonicidae. .'American Mala-

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Bieler, Riidiger, .'\rthur S, Merrill, and Kenneth J, Boss, 1985.

P.scudotorinia bulli.si. new species (Gastropoda: Architec-

tonicidae) from subtropical Western Atlantic. The Nau-

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Boss, Kenneth J, and Arthur S. Merrill, 1984, Radular con-

figuration and the ta.xonomic hierarchy in the .Architec-

tonicidae (Gastropoda), Occasional Papers on Mollusks,

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Costa, Oronzio-Gabriele, 1841 (May 12), Fauna del Regno

di Napoli, .Animali Molli, Classe III, Gasteropodi, Petti-

nibranchi, Famiglia I, Trocoidei, genera Solarium, Tro-

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Costa, Oronzio-Gabriele. 1844. Catalogo de testacei viventi

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Emerson, William K. 1983, New records of prosobranch gas-

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THE NAUTILUS 101(l);48-49, 1987

Page 48

The Status of Tritonium viridulum Fabricius, 1780

\1. G. Harasewych

Richard E. Petit

Department of Invertebrate Zoology

National Museum of Natural History

Smithsonian Institution

Washington, DC 20560, USA

In the last issue of this journal, an article (Sneli and

Stokland, 1986:121-124) was published on the taxonom-

ic status of Tritonium viridulum Fabricius, 1780. That

article contained a number of errors of fact and omission

which we feel should be pointed out immediately to

prevent additional confusion about the taxon involved.

Sneli and Stokland (1986:121-122) cite Dall's (1887)

claim that the holotype of Tritonium viridulum Fabri-

cius was a Bela. They further quote Dall as saying that

Defrancia viridula Moller, 1842, was founded on the

same specimen. Later in their article, Sneli and Stokland

(p. 122, 123) treat Tritonium viridulum Fabricius and

"Defrancia viridula Moller" as two distinct taxa. As

pointed out by Pilsbry (1938:116), Moller did not de-

scribe a new taxon as Defrancia viridula, but simply

transferred what he considered to be Tritonium viri-

dulum Fabricius to the genus Defrancia. This is very

clear in Moller (1842:87). The "type lots" of "Defrancia

viridula Moller", referred to by Sneli and Stokland (1986:

122, 123) are not types, but represent what Moller con-

sidered to be "Defrancia viridula (Fabricius)". For ad-

ditional discussion on nomenclatural problems involving

the misidentification by Moller, see Pilsbry (1938).

Sneli and Stokland mention "two dry specimens of

Moller's viridula from Greenland which are identified

to 'Bela viridula M. Sars' by Morch. Michael Sars never

described any species with this name, but the sample

could indicate that Morch had Moller s species in mind

when he claimed to have discovered that this and Fa-

bricius species were founded on the same specimen."

While it is true that Michael Sars did not propose the

binomen "Bela viridula", G. O. Sars (1878) listed, phys-

ically described, and illustrated Admete viridula Fabri-

cius (on p. 216, pi. 13, fig. la) and Bela viridula Moller

(on p. 235-236, pi. 16, figs. 7, 8). It appears from Sars'

text that the latter listing may have been based on spec-

imens identified by Morch.

Bouchet and Waren (1985:257) declare that "Morch

never mentioned [the supposed coequivalence of T. vir-

idula Fabricius and "Defrancia viridula Moller"] in any

paper and even the last time he used the name viridula

(1877) shortly before his death, he used it in the accus-

tomed sense." A partial review of Morch s publications

yields the following citations:

1852:101. Admete viridula Fabr. (with A. crispa Moll,

in synonymy).

1857:10. Cancellaria (Admete) viridula Fabr. (with

"Admete crispa Moll., C. buccinoides Couth.,

C. couthoyii [sic] Jay in synonymy).

1868:30. Admete viridula Fabr.

1869:22. Admete viridula Fabr. var. grandis

All published evidence clearly shows that Morch's con-

cept of Admete viridula Fabricius was exactly the same

as that of all authors except Dall, a few later workers

who accepted Dall's opinion without question, and the

authors of the paper under discussion.

Sneli and Stokland state that "Fabricius Tritonium

viridulun^ seems difficult to identify with any species "

and "should, since the holotype is lost, be regarded as a

nomen dubium." Pilsbry (1938:116) made the comment

that "while there are no figures in [Fauna Groenlandica],

the description is good, for the time, and the species, as

Admete viridula (O. Fabr.) is everywhere accepted. " In

their work on Admete, Bouchet and Waren (1985:257)

designated a neotype for Tritonium viridulum Fabri-

cius, stating that doing so "will make it possible to keep

the name which has been used in a single sense in Eu-

rope for 200 years". The neotype selected is one of Moll-

er's specimens. Admete viridula (Fabricius), as now fixed

by the neotype designation, was properly identified by

a large number of authors over the past two centuries.

For a partial list of correctly identified references to

Admete viridula (Fabricius), see Harmer (1918:406). In

recent years at least two papers have been published, in

addition to the cited paper by Bouchet and Waren,

treating Admete viridula (Fabricius) and identifying it

as the species fixed by the neotype designation (Fretter

& Graham, 1985; Harasewych and Petit, 1986).

It was also stated by Sneli and Stokland that the oldest

name for "Admete viridula auctt" is Cancellaria buc-

cinoides Couthouy, 183S, but that that name is a pri-

mary homonym of "Cancellaria buccinoides W. Wood,

1828". Couthouy s usage is preoccupied, but it is by

M. G. Harasewvch and R. E. Petit, 198'

Page 49

Cancellaria bticcinoides G. B. Sowerby I, 1832. This

binomen was never used by Wood, nor have we found

any other reference attributing it to him.

In short, we find Sneh and Stokland s conclusions to

be untenable. Admete viridula (Fabricius, 1780) is, and

has been, a valid, identifiable, and often cited taxon.

LITERATURE CITED

Bouchet, P. and A. Waren. 1985. Revision of the northeast

.Atlantic bath>ai and ab\ssal Neogastropoda excluding

Turridae (Mollusca, Gastropoda). Bollettino Malacologico,

Suppleinento 1:121-296, figs. 282-723.

Dall, W. H. 1887. Supplementary notes on some species of

mollusks of the Bering Sea and vicinity. Proceedings of

the U.S. National Museum 9:297-309, pis. 3, 4.

Fabricius, O. 1780. Fauna Groenlandica. Hafnia et Lipsiae.

452 p.

Fretter, V. and A. Graham. 1985. The prosobranch molluscs

of Britain and Denmark. Pt. 8 — Neogastropoda. Journal

of Molluscan Studies, Supplement 15:435-556, figs. 310-

376.

Harasewvch, M G. and R. E. Petit. 1986. Notes on the mor-

phology of Admctc viridula (Gastropoda: Cancellariidae).

The Nautilus 100(3);85-91, figs. 1-11.

Harmer, F. W. 1918. The Eocene Mollusca of Great Britain,

being supplementary to S. V. Wood's monograph of the

Crag Mollusca. Pt. 3. Palaeontographical Society 70(337):

303-461, pis. 33-44,

Moller, H. P. C. 1842. Index Molluscoruni Groenlandiae.

Naturhistorisk Tidsskrift 4:76-97.

Morch, O A L 1852 Catalogus Conchyliorum quae reliquit

(. . .) de Yoldi. 1. Hafniae, 172 p.

Morch, O. .\. L. 1857. Fortegnelse over Gronlands Bloddyr.

In: Rink, H. J. Gronland geographisk og statistik beskriv-

et, p. 75-100 [separate, p. 3-28].

Morch, O. A. L. 1868. Fauna Molluscoruni Islandiae. Viden-

skabelige Meddelelser fra den naturhistoriske Forening i

Kjobenhavn (ll-13):l-43.

Morch, O. A. L. 1869. Catalogue des Mollusques du Spitz-

berg. Memoires de la Societe Malacologique de Belgique

4:7-32 [separate, p. 3-28].

Morch, O. A L. 1877. Mollusca In: Rink, H. Danish Green-

land, its people and its products. S. King, London, p. 435-

442.

Pilsbrv, H. A. 1938. On the histor\ and status of Lora Gistel.

The Nautilus 51(4):115-118.

Sars, G. O. 1878. Mollusca regionis arcticae Norvegiae. Brog-

ger, Christiania, 466 p.

Sneli, J. -A. and O. Stokland. 1986. On the taxonomical status

of Tritonium viridulum Fabricius, 1780 (Gastropoda:

Cancellariidae). The Nautilus 100(4):121-124, figs. 1-7.

Sowerby, G. B., I. 1832. In: Broderip, W. J. and G. B. Sow-

erby. [Characters and descriptions of new species of Mol-

lusca and Conchifera collected by Mr. Cuming] Proceed-

ings of the Zoological Society of London 17:50-61.

Wood, W. 1828a. Index Testaceologicus; . . . [third edition

of this title, but called "Second Edition, corrected and

revised " on title page]. London, p. i-xxii, [-1- 1,] 1-212,

38 pis.

Wood. W. 1828b. Supplement to the Index Testaceologicus;

or a catalogue of shells, British and foreign. London, p. i-

iv, [-1- 1,] 1-.59, 8 pis.

THE NAUTILUS 101(1):50, 1987

Page 50

News and Notices

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» • . J • < • 1 ! 1

THE NAUTILUS

Volume 101, Number 2

April 28, 1987

ISSN 0028-1344

A quarterly devoted

to malacology.

Marine Biological Laboratory

LIBRARY

MAY 7 1987

3

Woods Hole, Mass.

i— ^— — — ^— — ir-w^ii I Mil iwiii.^J

s. I

EDITOR-IN-CHIEF

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Division of Mollusks

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THEt^NAUTILUS

CONTENTS

' Marine Biological Laboratory

LIBRARY

MAY 71987

Woods Hole, Mass.

Volume 101, Number 2

April 28. 1987

ISSN 0028-1344

Paula M. Mikkelsen and

Paul S. Mikkelsen

Redescription of Acteocina recta and A. lepla, two species

of cephalaspidean gastropods from the western Atlantic

51

James F. Quinn. Jr.

A revision of the Seguenziacea Verrill, 1884 (Gastropoda:

Prosobranchia). II. The new genera Hadrocontis,

Rotellenzia, and Asthelys

59

Geerat J. Vernieij,

Richard B. Lowell,

Linda J. Walters, and

Jessica A. Marks

Good hosts and their guests: Relations between trochid

gastropods and the epizoic limpet Crepidula adiinca

69

Charles W. Randall and

Robert F. Martin

Distribution, abundance, and movement patterns of

shoreline chitons of the Caribbean coast of Mexico

75

Richard S. Houbrick

Transfer of Cerithiopsis crystallina Dall to the genus

Varicopeza Griindel, famih Cerithiidae (Prosobranchia:

Gastropoda)

80

H. Lee Fairbanks

Identity and status of Philomycus pennsylvanicus Pilsbry,

1894 (Gastropoda: Pulmonata: Philom\cidae)

86

Perry A. Peon

The diet and feeding behavior of Caduhis tolmiei Dall,

1897 (Scaphopoda: Siphonodentaiioida)

88

W. Bruce Saunders,

Larry E. Davis, and

Ron L. knight

Sympatric species of Nautilus (N. pompilius and N.

scrobiculatus) in the .\dmiralty Islands, Papua New

Guinea

93

News and Notices

100

THE NAUTILUS 101(2):51-58, 1987

Page 51

Redescription of Acteocina recta and A. lepta, Two Species

of Cephalaspidean Gastropods from the Western Atlantic

Paula M. Mikkelsen

Paul S. Mikkelsen

Harbor Branch Oceaiiographic

Institution, Inc.

5600 Old Dixie Highway

Ft^ Pierce, FL 33-150-9719, USA

ABSTRACT

Acteocina recta (Orbigny, 1841) and A. lepta Woodring, 1928,

both from the Western Atlantic, are redescribed on the basis

of type material and other specimens from museums and pri-

vate collections. Acteocina recta, for which a lectotype is des-

ignated, is characterized by its generally small (1-2 mm), thin

shell, spiral striae, low spire, double-keeled shoulder, and ta-

pered protoconch, indicative of planktotrophic larval devel-

opment. It ranges from eastern Florida to Texas, and through-

out the Caribbean to Brazil. Acteocina lepta was originally

described as a Plio- Pleistocene fossil from Jamaica. It is thick-

shelled and spirally striate, with a low spire, double-keeled

shoulder, and bulbous protoconch, indicative of non-plankto-

trophic larval development; adults are 2-5 mm in length. In

the Recent fauna, it ranges from Bermuda and North Carolina

to Louisiana, and throughout the Caribbean to Brazil

INTRODUCTION

In the course of studying collections of Western .Atlantic

Acteocina species, numerous niorphot\ pes have been dis-

tinguished. Three of these, A. canaliculata (Say, 1826),

A. candei (Orbigny, 1841), and A. atrata Mikkelsen and

Mikkelsen, 1984, have already been recognized as valid

species (Mikkelsen & Mikkelsen, 1984). Two others. A,

recta (Orbigny, 1841 ) and A. lepta Woodring, 1928, have

often been misidentified in collections, and have fre-

quently been confused with each other. The present pa-

per redescribes the last two species on the basis of type

specimens and other live- and dead-collected material,

and redefines their geographic distributions.

MATERIALS AND METHODS

Dried and wet-preserved specimens from the following

museums and private collections were utilized to deter-

mine geographic and bathymetric distributions of these

species:

ANSP, Academ\' of Natural Sciences of Philadelphia,

Philadelphia, PA.

BM(NH), British Museum (Natural History), London.

Coovert Collection, Gary A. Coovert, Dayton, OH.

Edwards Collection, Amy L. Edwards, LTniversitv- of

Georgia, Athens, GA.

Finlay Collection, C. John Finlay, Palm Ba\', FL.

FSBC 1, Florida Department of Natural Resources,

Bureau of Marine Research, St. Petersburg, FL.

HMNS, Houston Museum of Natural Science, Hous-

ton, TX.

IRCZM, Indian River Coastal Zone Museum, Harbor

Branch Oceanographic Institution, Ft. Pierce, FL.

Keeler Collection, James H. Keeler, Tallahassee, FL.

Lee Collection, Harry G. Lee, Jacksonville, FL.

LIU, Southampton College (Long Island University),

Southampton, NY.

MCZ, Museum of Comparative Zoology, Harvard Uni-

versity, Cambridge, MA.

MORG, Museu Oceanografico, Rio Grande, Brazil.

Redfern Collection, Colin Redfern, Boca Raton, FL.

UNC-IMS, Institute of Marine Sciences, University of

North Carolina, Morehead City, NC.

USNM, National Museum of Natural History, Smith-

sonian Institution, Washington, DC.

Williams Collection, Peggv Williams, Sarasota, FL.

Worsfold Collection, Jack Worsfold, Freeport, Baha-

mas.

In "Material Examined" sections, an "L" following

the number of specimens indicates that at least one of

the specimens in the lot was live-collected and contained

soft parts; an "E indicates that all specimens w ere empty

shells.

Shell terminology is after Smith (1967:758-760) and

Knight (1952:7-9); radular terminology is after Bertsch

(1977:110-111). Radulae and gizzard plates were ex-

tracted and prepared for light microscopy using the

method previouslv described (Mikkelsen & Mikkelsen,

1984; Mikkelsen, 1985).

Page 52

THE NAUTILUS, Vol. 101, No. 2

Figures 1-4. Acteocina recta. 1. Syntypes, BM(NH) 1854.10.4.16. Left 1.41 mm (lectotype), center 1.S5 mm (paralectotype),

right 1.76 mm (paralectotype). 2. Adult shell from off Ft. Pierce, Florida, 1.62 mm. 3. Specimen in figure 2, oblique view of

p. M. Mikkelsen and P. S. Mikkelsen, 1987

Page 53

SYSTEMATIC RESULTS

Genus Acteocina Gray, 1847

Acteocina recta (Orbigny, 1841)

(figures 1-6)

Bulla recta Orbigny, 1841:131. 1842: pi 4 bis, figs, 17-20.

Material examined: Syntypcs: 3 specimens [lectotype

(1.41 mm), 2 paralectotvpes (1.85 mm, 1.76 mm frag-

ment)], BM(NH) 1854.10.4.16. Other material: 632

specimens (ANSP, HMNS, LIU, MCZ, MORG, USNM,

Worsfold Collection), including the follovsing as repre-

sentative \oucliers: Florid.\: Oi^ Ft. Pierce: IIL, IRCZM

065:02411, 065:M0063 (microslide with radula and giz-

zard plates); 2L, USNM 859080; 2L, USNM 859081; 6L,

ANSP A11629; 6L, BM(NH) 1986149 (including mi-

croslide with radula and gizzard plates). — Bahia Honda

Key: IE, USNM 358296— Louisiana: South Pass: 30E,

HMNS 9222.— Texas: Southeast of Freeport: 15L, HMNS

8122.— North of Port Isabel: 9E, HMNS 8151 —Greater

Antilles: Northwestern Cuba: IE, USNM 358229.—

Cavman Islands: IE, ANSP 295944 —Haiti: 2E, USNM

859087.— Bahamas: North of Abaco: IE, MCZ 294082.—

Lesser Antilles: British Virgin Islands: 5L, ANSP

351676.— Antigua: IE, USNM 859088; 6E, ANSP 8220.—

West Grenada: IE, ANSP 296955 —Central America:

Belize: 6E, ANSP 285386— Guatemala: IE, ANSP

76460.— Panama: 2E, ANSP 200034— South America:

South Bahia, off eastern Brazil: IE, MORG 20.110 (spec-

imen subsequently lost).

Original description: Orbignv (1841:131) originally de-

scribed Bulla recta from the Antilles as "oblong, straight,

cylindrical, uniform throughout its length, slender, frag-

ile, shining, displaying nevertheless, under magnifica-

tion, signs of transverse striations. Spire projecting, very

short, strongly channeled at the suture. Aperture linear,

straight behind, suddenK enlarging at the front, colu-

mella simple, without teeth. Color uniformly white." He

distinguished the species by its strongly cylindrical shape

and spiral striations, and described its protoconch as

"transverse to the spiral axis," or hyperstrophic.

Type material: The type material of Bulla recta (figure

1) consists of three specimens, all originally glued to a

strip of black paper. The smallest specimen (1.41 mm

length), still glued to the paper, has an intact protoconch,

highly evident spiral striae, and has retained its trans-

parency. A second specimen (1.85 mm length), although

more worn than the first, shows fine spiral striae and a

slightly glossy surface. The third specimen (1.76 mm

length), consisting of a fragmented body whorl, is of a

size and shape to be positively identified as A. recta. The

latter two specimens are loose, but have glue and paper

remnants on their dorsal surfaces. The locality given on

the label is "Antilles."

The smallest syntype (figure 1, left), being the best

representative of the species-specific characters, is here

designated as lectotype for Acteocina recta. The re-

maining two specimens (figure 1, center and right) are

designated as paralectotypes.

Diagnosis: Teleoconch thin-walled, cylindrical, with fine

spiral striae throughout its length. Shoulder with rounded

keel adjacent to suture and sharp keel at shoulder; 2 keels

separated by concave trough. Protoconch tapered, in-

dicating planktotrophic development. Lateral radular

teeth each with a wing-like expansion bearing a single

row of denticles; rachidian teeth with 3 robust denticles

per half. LInpaired gizzard plate T-shaped.

Distribution: St. Lucie County, eastern Florida, to

southern Texas; Bahamas; Greater and Lesser Antilles;

Atlantic Panama; southeastern Brazil. Recorded living at

depths of 33-44 m; empty shells collected from 2-128 m.

Description: The orthostrophic, dextral teleoconch of

Acteocina recta (figure 2) is cylindrical with nearly par-

allel sides, and has fine spiral striae. Two to three whorls

are typical of adult (1-2 mm) specimens. The aperture

is narrow (i.e.. less than Vi of the shell width), paralleling

the side of the body whorl, and flaring anteriorly. The

columella, although "toothless" as Orbigny (1841) stated,

bears a single weak fold. The shell walls are thin and

transparent in fresh material. The shoulder (figure 3) is

double-keeled; a sharp keel at the shoulder is separated

from a rounded keel adjacent to the suture by a narrow

concave trough of var\ ing depth. The rounded keel and

concave trough are crossed by strong axial wrinkles. The

spire is nearK flat in specimens under 2 mm; in larger

individuals (to 2.5 mm), spire height is typically less than

20% of the shell length. The periostracum is thin and

transparent.

The smooth, hyperstrophic protoconch (figure 4) is

tapered and similar in shape to that of Acteocina ca-

naliculata (Say, 1826), which was shown to indicate

planktotrophic larval development (Mikkelsen & Mik-

kelsen, 1984: fig. 3, e-g).

The radular formula of Acteocina recta is 1-R-l, with

8-14 radular rows in adults (n = 6). The rachidian teeth

(figure 5, R) are centrally notched, with each rounded

half bearing three (rarely four) sharply pointed, robust

denticles. The lateral teeth (figure 5) are sickle-shaped

and unicuspid, with the cusp bearing a wing-like expan-

sion supporting one row of 4-6 denticles. A blunt basal

tubercle is present for articulation with adjoining lateral

teeth.

Three calcareous gizzard plates are present (figure 6):

a "pair of non-identical, but similarly elongated, plates

shoulder. Scale bar = 40 nm. 4-. Specimen in figure 2, protoconch showing tapered, planktotrophic-type morphology. Scale bar

40 ^m.

Page 54

THE NAUTILUS, Vol. 101, No. 2

Figures 5-8. Radulae and gizzard plates. Acteocina recta: 5.

Two rachidian (R) and two lateral teeth. Scale bar = 10 ^m.

6. Gizzard plates. Scale bar = 100 /im. A. lepta: 7. Two ra-

chidian (R) and two lateral teeth. Scale bar = 10 ^m. 8. Gizzard

plates. Scale bar = 100 txm.

opposes a larger "unpaired" plate. The unpaired plate

is most dorsal in the crawling animal and is distinctly

T-shaped (n = 5).

Remarks: Since its original description, Acteocina recta

has appeared in the literature mainly as an undiscussed

member of various Recent faunal lists {e.g., Gabb, 1873,

1881; Morch, 1875; Guppy, 1876; Arango y Molina, 1878;

Dall, 1889, 1903b; Smith, 1890; Ihering, 1915; Maury,

1922; Johnson, 1934; Lange de Morretes, 1949; Coomans,

1963; Marcus & Marcus, 1964; Abbott, 1974). One such

Bermudan record (Peile, 1926) has been found, by ex-

amination of voucher specimens (ANSP 141560; see A.

lepta synonymy), to be A. lepta. Pilsbry (1895) and Ver-

rill and Bush (1900) figured A. recta, gave brief synon-

ymies, and/or reiterated previous descriptions. In the

fossil literature, A. recta has been recorded from the

Miocene of Santo Domingo (Gabb, 1873; Maury, 1917,

1922), the Oligocene of Jamaica (Dall, 1903a), and the

Miocene and Pliocene of Costa Rica (Olsson, 1922, and

Gabb, 1881, respectively). None of these previous rec-

ords, with the e.xception of Peile (1926), have been ver-

ified through specimen examination, although all fall

within the verified geographic range of the species.

Some workers (Dall, 1889; Maury, 1917; Olsson, 1922;

Woodring, 1928) have cited Tornatina coixlacrijma

Guppy, 1867, from the Jamaican Miocene, as a synonym

(in whole or in part) of Acteocina recta. However, the

neotype of T. coixlacrijma (I'SXM 369322, designated

by Woodring, 1928) differs markedly from A. recta in

conchology in having a larger, more robust shell with a

deeply channeled suture and bulbous protoconch.

Caution must be used in dealing with small specimens

of Acteocina candei (Orbigny, 1841), which are often

thin-shelled, low-spired and lack distinct subsutural

sculptural bands, thus resembling specimens of A. recta.

The former species may be distinguished in these cases

by the absence of spiral striae.

Acteocina lepta Woodring, 1928

(figures 7-13)

Acteocina lepta Woodring, 1928:121, pi. 2, fig. 5.

Retusa candei (Orbigny, 1841). Warmke and Abbott, 1962:

143, pi. 27g; Rice and Kornicker, 1965:129, pi. 8, fig. 10.

Acteocina recta (Orbigny, 1841). Peile, 1926:85 [ref. ANSP

141560 (voucher specimens)].

Tornatina candei (Orbigny, 1841). Rehder, 1981:635, fig. 356.

? Tornatina cijlindrica Emmons, 1858:181, fig. 182.

Material examined: Holotype: 3.78 mm, USNM

369320. Other material: 2,302 specimens (ANSP, FSBC

I, HMNS, IRCZM, LIU, MCZ, MORG, UNC-IMS, USNM,

and collections of Coovert, Edwards, Finla\ , Keeler, Lee,

Redfern, Williams, Worsfold) including the following as

representative vouchers: Bermuda: 24E, ANSP 141560. —

North Carolina: Off Cape Hatteras: IL, USNM

329930.— Off Cape Lookout: 3L, UNC-IMS 9858.1-3;

2L, IRCZM 065:02056, 065:M0057 (microslide with rad-

ula and gizzard plates). — South Carolina: IE, IRCZM

065:01930. — Georgia: IE, Edwards Collection. — Flori-

da: Off St. Lucie County: IE, FSBC I 26258.— Off Palm

Beach: 3E, ANSP 359158.— Off Miami: 9E, USNM

859089.— Key Largo: 18E, ANSP 336230 —Kev West:

2L, USNM 859090.— Off Sanibel: IL, MCZ 245062.—

Off Tampa: 2E, ANSP 358045.— Off Cape San Bias: 3E,

USNM 323422.— Louisiana: Off Cameron: 3E, HMNS

8161. — Greater Antilles: Northern Cuba: 2E, Finlay

Collection.— Southeastern Cuba: IE, USNM 383696 —

Jamaica: 27E, USNM 859091.— Cayman Islands: 5E,

ANSP 296098.— Dominican Republic: 2E, USNM

807258.— Western Puerto Rico: IE, USNM 859092.—

Bahamas: Greater Abaco Island: 3E, ANSP 357901.—

Bimini Islands: 9E, USNM 859093— Andros Island: 548E,

USNM 859094.— Lesser Antilles: Barbados: 2E, USNM

500361. — Central America: Yucatan: IE, USNM

667674. — South America: Northern Brazil: 8E, MORG

22.365.

Original description: Acteocina lepta was originally

described as a fossil from Bowden, Jamaica: "shell small,

slender, tightly coiled, subcylindrical, bod) whorl ta-

pering gently at base. Nuclear whorls forming a large

tip. Anal fasciole concave, bearing axial puckers, bound-

ed by sharp-edged ridges. Middle of outer lip slightK

constricted. Umbilical groo\e narrow , deep (Woodring,

1928:121). Although presumed by Woodring to be Late

Middle Miocene, Blow (1969) and Robinson and Lamb

(1970) have shown the type locality to be Pliocene to

Early Pleistocene in age.

p. M. Mikkelsen and P. S. Mikkelsen, 1987

Page 55

Figures 9-13. Acteocina lepta. 9. Holotype, 3.78 mm, USNM 369320. 10. Adult shell from Cuba, 4.50 mm. 11. Specimen in

figure 10, oblique view of shoulder. Scale bar = 100 ^m. 12, 13. Specimen in figure 10, protoconch showing bulbous, non-

planktotrophic morphology. Scale bars = 40 ^m.

Page 56

THE NAUTILUS, Vol. 101, No. 2

Type material: The holotype of Acteocina lepta (figure

9), although worn, is in generally good condition and has

an intact protoconch. A bored hole with worn edges is

on the ventral surface of the body whorl. No sculptural

details can be discerned on the shell surface, e.xcept for

distinct a.xial wrinkles on the shoulder.

Diagnosis: Teleoconch thick-walled, porcellaneous, cy-

lindrical, fineK spirally striate throughout its length.

Shoulder w ith rounded, elevated keel adjacent to suture,

plus sharp keel at shoulder, separated by a slightly con-

cave, axially wrinkled area. Protoconch well-protruded

and bulbous, indicating non-planktotrophic develop-

ment. Lateral radular teeth each with a wing-like ex-

pansion bearing a single row of denticles. Rachidian teeth

with robust base, median buttress, and fine denticles.

Unpaired gizzard plate heart-shaped.

Distribution: Bermuda; North Carolina to the Florida

Keys and to Louisiana; throughout the Caribbean, in-

cluding the Greater and Lesser Antilles, the Bahamas,

Yucatan, and to northern Brazil. Plio-Pleistocene to Re-

cent. Recorded living at depths of 7-226 m; empty shells

collected from 2-457 m.

Description: The orthostrophic, dextral teleoconch of

Acteocina Icpta (figure 10) is c\lindrical, with nearly

parallel sides, and is finely spirally striate. The shells are

rather thick, giving a porcellaneous appearance to av-

erage-sized (3-5 mm) specimens. The columella bears a

single strong fold. In live-collected or fresh-dead mate-

rial, a thin, light Nellow periostracum is evident. The

shoulder (figure 11) is sharply keeled, with a second

elevated keel just below the suture. Between these keels,

the rather wide slope is slightly concave and axialK wrin-

kled The spire is generally very low, usually 7-9% (max-

imum 13%) of the total length.

The smooth, hyperstrophic protoconch (figures 12, 13)

is typically well-protruded above the first teleoconch

whorl. It is bulbous and similar in shape to that of Ac-

teocina atrata Mikkelsen and Mikkelsen, 1984 (Mikkel-

sen & Mikkelsen, 1984: fig. 8, e-g). This type of proto-

conch has been observed in at least ten species of

cephalaspids in the Western Atlantic alone, and is known

in two, including A. atrata, to reflect capsular meta-

morphic (= direct) larval development (personal obser-

vation). However, some recent workers (Turner et al.,

1985) have surmised that prosobranch protoconchs of

this same general size and morpholog\ indicate lecitho-

trophic (= non-feeding planktonic) development. Given

this apparent discrepancy, the best we can infer from

the available evidence is that A. lepta probabK' has non-

planktotrophic development.

The radular formula of Acteocina lepta is 1-R-l with

about 16 rows in adult specimens (n = 3). The rachidian

teeth (figure 7, R) are centrally notched with each half

bearing 6-9 fine, sharply pointed denticles. The base of

the rachidian is robust (staining dark pink in acid fuchsin)

and extends along the center of the tooth in the form of

a triangular buttress. The apex of this buttress meets the

approximate center of the indentation between the two

halves of the tooth. The lateral teeth (figure 7) are sickle-

shaped and unicuspid, with the cusp bearing a wing-like

expansion supporting one row of 10-12 denticles. A blunt,

basal tubercle is present for articulation with adjoining

lateral teeth.

The three subequal calcareous gizzard plates (figure

8) consist of a rounded heart-shaped "unpaired" plate,

and two elongated, nonidentical "paired" plates (n = 3).

Remarks: Acteocina lepta has been cited in the liter-

ature only once since its original description, from the

Middle Miocene of Santa Rosa, Veracruz, Mexico (Per-

rilliat, 1974). It has not been previously recorded as part

of any Recent fauna. The results of our previous work

on the type species A. canaliculata (see Mikkelsen &

Mikkelsen, 1984) allow the genus Acteocirm to be used

for this, and other, extant species.

Numerous museum lots of Acteocina lepta ha\e been

misidentified as A. recta. This may stem from a mis-

leading statement by Woodring (1928:121) who origi-

nally described A. lepta as "the Bowden representative

of and "smaller than" the living A. recta.

Acteocina lepta is similar in general appearance to

Tornatina persimilis Dall, 1895, from the Oligocene of

Florida, as noted by Woodring (1928). However, the

latter species (holotype, 3.02 mm, USNM 112607) has a

tapered, planktotrophic-type protoconch and completely

lacks spiral striations.

The original figure of the North Carolina Miocene

species Tornatina cylindrica Emmons, 1858, is ex-

tremely similar to Acteocina lepta. A search for type

material of Emmons species has been unsuccessful, mak-

ing determination of protoconch morphology and other

critical features impossible. The original description is

inadequate to distinguish it from other species, therefore,

T. cylindrica must be considered a nomen dubium.

Acteocina lepta bears close resemblance to Tornatina

liratispira E. A. Smith, 1872, the sole conchological dif-

ference being protoconch morpholog\. The four syn-

types of the latter species [BM(NH) 1860.5.2.29] were

examined; one of the four specimens was found to be A.

candei (Orbigny). As no live-collected specimens of T.

liratispira were available for dissection, radular and giz-

zard plate morphologies remain unknown. Determina-

tion of its proper generic placement and relationship with

A. lepta must therefore await further study. Tornatina

liratispira is here reported from the Bahamas, the Great-

er and Lesser Antilles, and the northern coast of Brazil,

at depths ranging from 35 to 106 m.

Acteocina lepta has been figured several times in the

literature as A. candei (Orbign\) (Warmke & Abbott,

1962; Rice & Kornicker, 1965; Rehder, 1981).

DISCUSSION

Morphological characteristics of Acteocina recta and A.

lepta are summarized in table 1.

Extreme caution is advised when identifying speci-

mens of these and other species of Acteocina sensii lato.

Key characters include shell shape and general sculpture.

p. M. Mikkelsen and P. S. Mikkelsen, 1987

Page 57

Table 1. Distinguishing characteristics of Actcocina recta and A. lepta.

A. recta

A lepta

Shell length

Shell shape

Spire height

Sutural keel

Trough between shoulder and sutural keels

Shell walls

Columella

Periostracum

Protoconch

Inferred type of larval development

Lateral tooth denticles

Rachidian tooth denticles

Rachidian buttress

Unpaired gizzard plate

1-2 mm

c\ lindrical, parallel sides

fiat to low (<20?'c)

rounded

narrow, concave

thin, transparent

weak fold

thin, transparent

tapered

planktotrophic

4-6

3 per half

not present

T-shaped

3-5 mm

c\ lindrical, nearK parallel sides

flat to low (7-13'7)

sharp, elevated

wide, concave

thick, porcellaneous

strong fold

thin, light yellow

bulbous

non-planktotrophic

10-12

6-9 per half

present

heart-shaped

shoulder sculpture, type of protoconch, radula, and giz-

zard plates. Spiral striae are often exceedingly fine and

may be imperceptible in wet {i.e., alcoholic) specimens;

momentary dry ing of the shell surface is freciuently nec-

essary for examination. Worn shells, especially those with

eroded surfaces and/or missing or worn protoconchs are

particularly problematic. All species of Acteocina (and

other closely related genera) that we have examined thus

far are conchologically separable. However, these con-

chological distinctions may be in the protoconch only. A

thorough understanding of species-specific shell char-

acters, in combination with radular and gizzard plate

characteristics, is essential.

ACKNOWLEDGEMENTS

The time required to conduct this work was generously

allowed by Dr. Robert W. Virnstein (Seagrass Ecosystems

Analysts, Ft. Pierce, FL) and Mr. John E. Miller [Harbor

Branch Oceanographic Institution (HBOI), Ft. Pierce,

FL]. Our thanks extend to the following for arranging

examination of museum specimens entrusted to their

care: the late Dr. Joseph Rosewater, Mr. Frederick J.

Collier, and Mr. Warren C. Blow (USNM); Dr. John

Taylor and Ms. Kathie Way [BM(NH)]; Dr. Robert Rob-

ertson and Ms. Mary A. Garback (ANSP); Dr. Kenneth

J. Boss, Dr. Ruth D. Turner, and Ms. Carey Westermann

(MCZ); the late Dr. Thomas Pulley and Ms. Constance

Boone (HMNS); Mr. Hugh J. Porter (UNC-IMS); Dr. E.

de C, Rios (MORG); Mr. William G. Lyons (FSBC I);

and Ms. Amy L. Edwards (LIU, and University of Geor-

gia, Sapelo Island). We also thank the following for al-

lowing examination of specimens in their personal col-

lections: Gary A. Coovert (Davton, OH), C. John Finlay

(Palm Bay, FL), James H. Kee'ler (Tallahassee, FL), Har-

ry G. Lee (Jacksonville, FL), Colin Redfern (Boca Raton,

FL), Peggy Williams (Sarasota, FL), and Jack Worsfold

(Freeport,'Bahamas). P. A. Linley (HBOI) and R. Bieler

[Smithsonian Marine Station at Link Port (SMSLP), Ft.

Pierce, FL] read and commented on various versions of

the manuscript. J. Piraino (SMSLP) and T. Smoyer (HBOI)

assisted with SEM and light photography, respectively.

K, Metzger and C. Browder (HBOI), and the staff of the

Division of Mollusks, USNM, assisted in literature ac-

quisition.

This is Contribution Number 546 of Harbor Branch

Oceanographic Institution, Inc.

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the supervision of Alexander Agassiz, in the Gulf of Mexico

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Coast Survey Steamer "Blake," Lieut-Commander C. D.

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THE NAUTILUS 101(2):59-68, 1987

Page 59

A Revision of the Seguenziacea Verrill, 1884

(Gastropoda: Prosobranchia). II. The New Genera

Hadroconus, Rotellenzia, and Asthelys

James F. Quinn, Jr.

Florida Department of Natural

Resources

Bureau of Marine Research

100 Eigfitfi Ave.. S.E.

St. Petersburg, FL 33701, USA

ABSTRACT

Three new genera of the superfamil\ Seguenziacea are pro-

posed, Hadroconus is erected for two western Atlantic and one

western Pacific species formerly assigned to Basilissa Watson,

1879. Another species, Basilissa larnpra Watson. 1879. is here

made type-species of the monotvpic genus Rotellenzia. One

specimen from the syntype series of Carenzia carinata (Jef-

freys, 1877) from the North Atlantic Ocean is a juvenile of

Basilissa munda Watson, 1879, which is here established as

type-species of Asthelys new genus; Basilissa simplex Watson,

1879, is also assigned to this genus. Shells of Hadroconus alius

(Watson, 1879). Rotellenzia larnpra (Watson. 1879). and Asthe-

lys munda (Watson, 1879), are described and illustrated b\

SEM micrographs and/or light photographs. Comments on util-

ity of shell and radular characters for generic definitions are

presented.

INTRODUCTION

The systematics of the Seguenziacea Verrill, 1884, has

undergone extensive examination and revision during the

last 5 years. Prior to 1983, only six valid genera had been

established. An equal number of new genera were erect-

ed in 1983 [Marshall. 1983 (5); Quinn, 1983a (1)]. Sub-

sequent research on the western Atlantic fauna has re-

vealed two additional genera, and examination of the

unique specimen of Basilissa larnpra Watson, 1879, makes

a third new genus necessary.

In a previous paper (Quinn, 1983b), I noted that shell

characters were useful in distinguishing between taxa

and, in most cases, were the only characters available at

the species and genus levels. For example, differences in

size of protoconch, number and distribution of primary

and secondary sculptural elements (e.g., spiral carinae,

cords, threads, collabral riblets), features of the intersec-

tion of the sculptural elements (e.g., nodulose or smooth,

sharp or rounded nodules, laterally compressed or not),

t\pe of columellar tooth, etc., are important in species

discriminations. Some characters, especially shell pro-

portions, may or may not be adequate for species dis-

tinctions and must be evaluated on a case-by-case basis.

Ideally, delimitations of genera should entail analyses

of shell, radular, and anatomical characters. That ideal

is hampered in the Seguenziidae by lack of material

available for dissection (see summary in Quinn, 1983b).

As a result, all genera have been established principally

on the basis of subjective evaluations of shell features,

sometimes augmented by a description of the radula.

Despite this approach, with the attendant potential for

unnecessary generic splitting, authors prior to 1970 \\ ere

very conservative in erecting new genera. In three recent

papers (Vlarshall, 1983; Quinn, 1983a, b), generic con-

cepts of seguenziids have been refined, again based prin-

cipally on conchological characters, but no author has

presented a discussion of shell characters that, when used

in combination, are useful in delimiting genera. I take

the opportunity to do so here.

Shell shape: With few exceptions, shell shape gives a

good first approximation of generic placement. The fol-

lowing definitions of shell shape w ill be used in this and

subsequent papers; (1) conical — spire height greater than

aperture height, sides of spire flat or almost so, sutures

not impressed, base flat to weakly convex (Thelyssa Bay-

er, 1971; Thelys.sina Marshall, 1983, Basilissa Watson,

1879; Hadroconus new genus; Asthelys new genus); (2)

depressed conical — similar to (1) but spire height ap-

proximately equal to aperture height and base rather

strongly convex (Fluxinella Marshall, 1983; Botellenzia

new genus); (3) conico-turbinate — spire height greater

than aperture height, spire weakly to strongly gradate,

sutures weakly to strongly impressed, base flat to weakly

convex (Aiicistrobasis Dall, 1889; Carenzia Quinn, 1983;

Segiienziella Marshall, 1983; Basilissopsis Dautzenberg

and Fischer, 1897; Seguenziopsis, Marshall, 1983); (4)

ovate-conical — spire height greater than aperture height,

sides of spire flat or almost so, sutures weakK impressed,

base strongly convex [Segiienzia Group III of Quinn,

1983b (this group being described by Marshall, personal

Page 60

THE NAUTILUS, Vol. 101, No. 2

communication)]; and (5) ovate-turbinate — similar to (4)

but with spire strongly gradate and sutures often strongly

impressed (Seguenzia Jeffreys, 1876; Guttula Schepman,

1908).

.Midwhorl angulation: Presence or absence of a mid-

whorl angulation is consistent within genera, with one

exception (see below). "Midwhorl angulation" includes

any angulation that is formed along, although not nec-

essarily confluent with, the anterior (abapical) edge of

the posterior labral sinus and is usually weaker than the

peripheral carina. Only one genus {Guttula} lacks any

trace of this angulation at any stage of growth. Among

those with an angulation, there are three variations: (1)

angulation initialK absent, forming on second half of

first whorl, then disappearing again later in ontogeny

(Thelyssina and Asthelys); (2) angulation initially pres-

ent but becoming obsolete or absent after first one to

three whorls (Basilissa, most Ancistwbasis, Thelyssa,

Fluxinella, Carenzia, and Hadroconus); and (3) angu-

lation present on all whorls, often becoming a strong

carina (all other genera, plus Ancistwbasis regina Mar-

shall, 1983).

Axial sculpture: Axial sculpture above the periphery

usually comprises fine, sharp threads to strong cords trac-

ing, more or less exactly, the outline of the outer lip, but

is absent in a few genera. I use the term "sigmoid" to

denote the simple reversed S-shape, exemplified by An-

cistrobasis, and "collabral" for the more complex con-

figuration seen in Seguenzia (for general discussion I

include both types in the less precise term "axial"). Again,

this sculpture falls into several categories: (1) absent on

all whorls (Guttula, Fluxinella, Thelyssina, Seguenziop-

sis, and Asthelys); (2) initially present on first one or two

whorls as sharp, collabral threads, becoming weak, sig-

moid threads on subsequent whorls, or disappearing com-

pletely except for plications near the sutures, nodulation

of the midwhorl angulation, and/or plications on or cren-

ulation of the peripheral carina (Thelyssa, Seguenziella,

Carenzia, Rotellenzia, and Hadroconus); (3) initially

present on first one or two whorls as sharp, collabral

threads and persisting on all subsequent whorls as strong,

rounded, sigmoid cords (Basilissa, Ancistrobasis, and

Basilissopsis); and (4) present on all whorls as fine, sharp

collabral threads (Seguenzia and Seguenzia Group III).

The axial sculpture may extend onto the base as trans-

verse riblets or threads. The inclination of the axial riblets

with respect to the suture line (i.e., an imaginary line

connecting the intersections of the riblet ends with the

sutures) is useful as an additional character for distin-

guishing between genera that have similar shell mor-

phologies and sculptural types. At least two cases are

known for which this comparison obtains: in Basilissa

the axials are prosocline, but in Ancistrobasis they are

opisthocline; in Thelyssa the axials are prosocline, but in

Hadroconus they arc opisthocline.

Labral sinuses: The number of labral sinuses in the

shell lip is one of the more important characters, if not

the most important, in seguenziid systematics. Absence

of a sinus in the shell lip does not necessarily reflect a

corresponding lack of a sinus in the mantle edge, nor do

the shapes of axial riblets necessarily reflect the exact

shape of the posterior sinus. Most seguenziid genera have

either two or three sinuses (see Marshall, 1983; Quinn,

1983b). Guttula alone has none, and Thelyssina seem-

ingly has only one. Seguenzia, previously defined in part

by presence of three sinuses, actualK has a fourth (a

wide, open. Dared extension of the basal lip, rarely pre-

served in either dead- or live-collected material) located

in the extreme inner (adaxial) part of the basal lip; this

sinus corresponds to a papillate sinus in the mantle (Quinn,

1983b).

The shape of the posterior sinus has been described as

J-, reversed L-, U-, or V-shaped (Quinn, 1983b). How-

ever, this actually was a description of the shape of the

axial riblets in the selenizone behind the sinus itself. (1)

The J- and reversed L-shapes are merely variations on

a common theme in which the lower arm of the sinus is

essentially parallel to the suture line, and the apex (closed

end) is broadly and evenly rounded (Seguenzia, Se-

guenzia Group III, Hadroconus, and possibK Thclys.sa).

(2) The V-shape is that in which the upper and lower

arms of the sinus are divergent and the apex is narrowly

rounded (Carenzia, Seguenziella, Fluxinella, Rotellen-

zia). (3) The U-shape should actualK, and loosely, be

termed "broadly U-shaped", because the apex is very

broadly and evenly rounded, but the upper and lower

arms of the sinus are divergent, not parallel (Ancistro-

basis. Basilissopsis, Asthelys. and probably Basilissa). (4)

The sinus edge in Seguenziopsis apparently sweeps for-

ward in a sigmoid, opisthocline line with the posterior-

most point at the suture.

As indicated above, the true shape and depth of the

posterior sinus is not necessariK reflected in the shape of

the axial sculpture. For example, in Hadroconus the

sigmoid axial threads suggest a very shallow, broadly

U-shaped sinus similar to that of Ancistrobasis, but the

sinus of the former is actualK considerabK deeper than

that of Ancistrobasis, and the lower arm is parallel, or

nearly so, to the suture line. However, in Ancistrobasis,

Basilissopsis, and probably Basilissa, the sigmoid axials

accurately trace the sinus (Marshall, 1983; Quinn, 1983b,

unpublished observations). This does not, however, ob-

viate the systematic value of the shapes of axials for

discriminating between closely related taxa (Quinn, in

preparation).

Depth of the posterior sinus is defined here b> arbitrary

sinus depth: shell diameter ratios (X) — very shallow =

X < 0.10; shallow = 0.10 < X < 0.20; moderate =

0.20 < X < 0.30; deep = X > 0.30.

Umbilicus: The presence, absence, and relative width

of the umbilicus may or may not be of systematic sig-

nificance at the generic level; characteristics of the um-

bilicus usualK are useful onK at the species level. How-

ever, presence of an umbilical septum is a rare feature

in the Seguenziidae, as it also is in the Trochacea. An

umbilical septum is known only in Basilissa superba

J. F. Qiiinn, Jr., 1987

Page 61

Watson, 1879, and Tliclyssa callisto Bayer, 1971, and is

here considered autapomorphic in Imtli genera.

Radula: The snperfamil\ has been characterized b\' the

presence of a single pair of lateral teeth and more than

two pair of marginal teeth in each radular tooth-row

(Qiiinn, 1983b). Including the three new genera defined

here, radulae have been illustrated for nine of the fifteen

described genera (including Scg(/('?i;ia Group III). These

illustrations seem to indicate three distinct types of lateral

teeth: (1) Type I is broadly triangular, with the dentic-

ulate cusp not narrowed {Ancistrohasis, Fluxinella, Had-

ruconus. and Guttula in part); (2) Type II has a broad,

triangular base, but with a long, narrow cusp arising from

the proximal corner (Seguenzia, Seguenziella and Ro-

tellenzia); and (3) Type III is a simple, triangular tooth

base lacking a cusp (Guttula in part, Carcnzia, and Se-

guenzia Group III). At present, structure oi the rhach-

idian and number of marginals cannot be satisfactorily

categorized.

In summary, characters of genus-level importance in-

clude shell shape, expression and persistence of a mid-

whorl angulation, expression and shape of axial sculpture,

shape of the posterior labral sinus, presence or absence

of an umbilical septum, and shape of the lateral tooth

of the radula. The number of labral sinuses is probably

significant at higher taxonomic levels. Features not nec-

essarily useful for discrimination of genera include pres-

ence or absence of an umbilicus or columellar tooth and,

in most cases, spiral sculpture. However, it must be stressed

that all characters must be used in combination, and

anatomical characters should also be included when

available. I believe that, although anatomical details are

lacking for most described genera, and radulae are un-

known for several, basing genera principally on shell

characters still has validit\ in the Seguenziidae, and I

am confident that anatomical characters, when known,

will confirm the validity of most, if not all, seguenziid

genera now defined on conchological characters.

Institutional abbreviations used in this paper are:

BM(i\H), British Museum (Natural History); MCZ, Mu-

seum of Comparative Zoology, Harvard University;

MNHN, Museum National d'Histoire Naturelle, Paris;

TAMU, Systematic Collection of Marine Organisms,

Te.xas A&M University; UMML, Rosenstiel School of Ma-

rine and Atmospheric Science, University of Miami;

USNM, U.S. National Museum of Natural History.

Hadroconus new genus

Basilissa Watson, 1879:593 (partim); 1886:96 (par(im).— Mar-

tens, 1881:56 (par(im).— Dall, 1881:48; 1885:34 (partim);

1889a:32, 384 [partim). 1889b:164-165 (partim); 1890:

354; 1927:109 (par(im).— Fischer, 1885:827 (partim).—

Pilsbrv, 1889:15, 419 (parhm). —Schepman, 1908:61 (par-

tim).—Maury, 1922:157 (par/im ).—Thiele, 1929:48 (par-

tim).—]o\ir\son, 1934:73 (par/im). —Wenz, 1938:276 (par-

(im).— Cotton, 1959:189 (par(im).— Keen and Cox, 1960:

1250 (par/im).— Clarke, 1962:12 (parfim).— Bayer, 1971:

123.— Abbott, 1974:39 (partim).— Quinn. 1979:49 (par-

tim); 1981:74 (partim). 1983b:729 (par/im).— Goryachev,

1979:70 (partim)— Boss, 1982:974 (partim).

Seguenzia: Daii, 1881:48 (partim).

Type-species: Basilissa alt a Watson, 1879; here desig-

nated.

Gender: Masculine.

Diagnosis: Shell small, conical, peripheralK carinate,

umbilicate, nacreous under thin outer porcelaneous lay-

er, white, polished; spire with flat to slightly concave

sides, sculptured by widely spaced, sigmoid axial riblets,

and fine spiral threads; periperal carina strong, overlaid

with several spiral threads, crenulated by terminations

of axial riblets; base slightly convex, with strong, flattened

spiral cords and/or narrow threads; umbilicus wide, deep,

funnel-shaped, bounded by strong, tuberculate cord; ap-

erture subrectangular; outer lip thin, with shallow pos-

terior sinus occupying adapical half of whorl, claw-like

near periphery; basal lip thin, w ith wide, shallow sinus

in outer part; columella straight, slightK' oblique, some-

what inflated medially, terminating in a rounded boss.

Remarks: Cossmann (1888) designated Basilissa super-

ba Watson, 1879, as type-species of Basilissa Watson,

1879, although B. alta Watson, 1879, has been the species

most frequently associated with that genus. Because that

type-designation may not be changed, Hadroconus is

erected for B. alia, B. sibogae Schepman, 1908, B. tvat-

soni Dall, 1927, and an undescribed western Atlantic

species. Together, these four species form a morpholog-

ically cohesive species-group that may be distinguished

from all other seguenziacean genera. Shells of these four

species are small ( < 10 mm), have spiral sculpture much

weaker than axial riblets, or predominantK absent, the

axial riblets are strongly sigmoid and opisthocline, and

the umbilicus lacks a septum. Shells of B. superba are

large ( > 20 mm), have spiral sculpture subequal to axial

riblets, axial riblets almost a simple prosocv rt arc except

for a weak opisthocyrt sinuation near the adapical suture,

axials weakly prosocline, and umbilicus partially covered

by a septum. In addition, shells of Hadroconus species

usually have height : width (h:w) ratios less than 1.0, those

of B. superba greater than 1.0; however, two specimens

of H. attus (UMML 30.8155) have h:w ratios of 1.03 and

1.07, and Okutani (1982) recorded two juvenile speci-

mens of B. superba with h:w ratios of 0.96 and 0.98 (he

did not indicate whether apical parts of these specimens

are intact).

Shells of Hadroconus are most similar to those of The-

lijssa Ba\er, 1971, but differ in that the axial riblets are

rather strongly sigmoid and opisthocline, and the um-

bilical walls lack callus and an umbilical septum. Had-

roconus and Thchjssa are apparentK' sister taxa sepa-

rated principalK by the autapomorphic umbilical septum

of Thelyssa.

Although I have not had an opportunity to examine a

properly preserved specimen of any species of Hadro-

conus, dried specimens of both H. alius and H. watsoni

were available for study and afforded the following ob-

Page 62

THE NAUTILUS, Vol. 101, No. 2

Figures 1 -5. Hadroconus alius (Watson, 1879). 1,2. Apertural and basal views of lectotype of Basilissa aha, BM(NH) 1887.2.9.351.

height 6.3 mm, maximum diameter 5.9 mm. 3. Apertural view of specimen from Gerda station G-965, UMML 30.7759 (SEM

micrograph, x 9), 4. Protoconch of another specimen from G-965 (SEM, x 140). 5. Same, apical view (SEM, x 9).

servations of external anatomy. A well-developed epi-

podium bears four (or five) to six epipodial tentacles. The

mantle edge has two broad sinuses, corresponding to the

basal and posterior labral sinuses of the shell; mid-dor-

sally is a prominent, seemingly papillate tentacle, to the

left of which is a narrow, C-shaped sinus which corre-

sponds to the peripheral angulation of the shell. The

esophagus, seen by transparency after the animals were

soaked in trisodium phosphate, e.xtends posteriori) from

the buccal area, sharply turns ventrally at the level of

the last intestinal turn, and then runs posteriorly along

the ventrolateral surface of the right intestinal tract. The

intestine is similar to that of Segitcnzia sp. cf. S. eritinia

V'errill, 1884 (Quinn, 1983b), but coils in the opposite

direction; the shape of the fecal string is also similar to

that of Seguenzia: oval with a shallow medial groove on

one side. The cephalic tentacles are long, papillate, ap-

prcssed basalK, and a long, slender penis arises just to

the right of the right cephalic tentacle. On either side

of the snout is a prominent, paddle-shaped oral lappet.

Etymology: From the Greek adros, stout, strong, and

konos, a cone.

Hadroconus alius (Watson, 1879)

(figures 1-5)

Basilissa alia Watson, 1879:597; 1886:100, pi. 7, fig. 8.— Mar-

tens, 1881:56.— Dall, 1881:48; 1885:34; 1889a:32, 384;

1889b: 164-165; 1890:.354,— Pilshrv, 1889:419, pi. 36, fig.

5.— Maurv, 1922:157.— Johnson, 1934:73.— Cotton, 1959:

189 —Clarke, 1962:12— Bayer. 1971:123, figs. 6D-G, l.\-

D.— Abbott, 1974:37, fig. 239— Quinn, 1983b;729, figs.

13, 28, 40.

Seguenzia dclicatula Dall, 1881:48; 1885:265.

Bfl.si/i.vxfl alta var. oxytoma Watson, 1886:100, pi, 7, fig. 8a. —

I'iLshry, 1889:421, pi. 36, fig. 4.

Basilissa alta var. delicatula: Dall, 1889a:384, pi. 22, figs. 2,

2a; 1889b:164-165. — Pil.shr\. 1889:421, pi. 48, figs. 3, 4.—

Maury, 1922:158.

Basilissa delicatula delicatula: Johnson, 1934:73.

Basilissa (Basilissa) alia: Quinn, 1979:50, figs. 83, 84.

J. F. Quiiin, Jr., 1987

Page 63

Material examined: 1 specimen, UMML 30.8156; Co-

lumbus Iselin sta. CI-356, 24°28.3'N, 77°29.5'W, 1,597

m; 40 foot otter trawl; August 20, 1975. — 1 specimen,

UMML 30.8146; Gerda sta. G-478. 24°15'N, 82°11'W,

543-348 m; 10 foot otter trawl; Januar\' 26, 1965.— 3

specimens, UMML 30.8152; Ccrda sta. G-967, 24°15'N,

82°26"W, 499-503 m; 10 foot otter trawl; February 2,

1968.— 1 specimen, UMML 30.8018; Gerda sta. G-1099,

24°12.5'N, 82°50'W, 622 m; 10 foot otter trawl; April 28,

1969—1 specimen, UMML 30.8144; Gerda sta. G-356;

24°11'N, 81°37'W, 672 m; 10 foot otter trawl; September

15, 1964.-1 specimen, UMML 30.8151; Gerda sta. G-966,

24°10'N. 82°22'W, 553-558 m; 10 foot otter trawl; Feb-

ruary 2, 1968.— 1 specimen, UMML 30.8147; Gerda sta.

G-815, 24°08'N, 79°48'W, 618 m; 10 foot otter trawl;

June 27, 1967.— 1 specimen, USNM 94941; Blake sta.

43, 24°08'N, 82°51"W, 620 m — 1 specimen, UMML

30.8145; Gerda sta. G-370, 23°54'N, 81°19'W, 1,281 m;

16 foot otter trawl; September 16, 1964. — 1 specimen,

UMML 30.7764; 2 specimens, UMML 30.8150; Gerda

sta. G-964, 23°46'N, 81°51'W, 1,390-1,414 m; 10 foot

otter trawl; February 1, 1968. — 5 specimens, UMML

30.7759; Gerda sta. 'G-965, 23°45'N, 81°51'W, 1,394-

1,399 m; 10 foot otter trawl; February 1, 1968.-1 spec-

imen, UMML 30.8022; Gerda sta.'G-1112, 23°44'N,

81°14'W, 2,276-2,360 m; 10 foot otter trawl; April 30,

1969.— 1 specimen, MCZ 7596; Blake sta. 41, 23°42'N,

83°13'W, 1,573 m.— 1 specimen, UMML 30.7692; Gerda

sta. G-963, 23°41'N, 82°16'W, 1,441-1,454 m; 10 foot

otter trawl; February 1, 1968. — 7 specimens, UMML

30.8149; Gerda sta. G-960, 23°30'N, 82°35'W, 1,692-

1,697 m; 10 foot otter trawl; January 31, 1968. — 5 spec-

imens. UMML 30.8148; Gerda sta. G-959, 23°25'N,

82°26'W, 1,830 m; 10 foot otter trawl; January 31, 1968.—

6 specimens, MCZ 135024; Atlantis sta. 2993, 23°24'N,

80°44'W, 1,061 m; 14 foot Blake trawl; March 15, 1938.—

1 specimen, MCZ 135022; Atlantis sta. 2987E, 23°19'N,

79°59'W, 576 m; 14 foot Blake trawl; March 13, 1938.—

1 specimen, MCZ 135023; Atlantis sta. 2988, 23°15'N,

79°57'W, 695 m; 14 foot Blake trawl; March 14, 1938 —

1 specimen (lost), MCZ 7598 (? holotype of Seguenzia

delicatula); 1 specimen, USNM 94943; Blake sta. 2,

23°14'N, 82°25"W. 1.472 m — 1 specimen, MCZ 135021;

Atlantis sta. 2989, 23°10'N, 80°04"W, 658 m; 14 foot

Blake trawl; March 14, 1938—11 specimens, MNHN;

Alaminos sta. 66-A9-15, 28°13.5'N, 87°04'W, 1,200-800

m; 10 ft midwater trawl; 1967. — Fragments, USNM

93805; A/foifross sta. 2384, 28°45'00"N. 88°15'30"W. 1,719

m; large beam trawl; March 3, 1885. — 3 specimens,

MNHN; Alaminos sta. 69-A11-7, 27°01.3'N, 94°43.5'W,

1,399 m; 3 m benthic skimmer; 1969. — 3 specimens,

TAMU 4-1950; Alaminos sta. 69-A11-74, 21°29'N,

96°41.5'W, 1,189-1.280 m; 3 m benthic skimmer; August

22, 1969—1 specimen, UMML 30.8153; John Elliott

Pillshunj sta. P-585, 21°02'N. 86°29'W, 567-570 m; 10

foot otter trawl; May 23, 1967. — 1 specimen. MCZ 135261;

Atlantis sta. 3370.' 20°47'N. 75°11'W, 829 m; 14 foot

Blake trawl; April 20, 1939—1 specimen, USNM 429445;

12 specimens, USNM 429465; 3 specimens, USNM un-

catalogued; Johnson-Smithsonian Deep-Sea Expedition

sta. 67, 18°30'12"N. 65°45'48"W, 329-512 m; 4 foot

dredge; February 23, 1933. — 1 specimen, BM(NH)

1887.2.9.351 (lectotype); 1 specimen. BM(NH)

1887.2.9.352 (paralectotype); Challenger sta. 24,

18°30'30"N. 65°05'30"W, 713 m; March 25, 1873.-1

specimen, USNM 214142; Albatross sta. 2750, 18°30'N.

63°3rW. 913 m; 2 foot ship's dredge; Noyember 27.

1887.-2 specimens, UMML 30.8327; John Elliott Pills-

bury sta. P-988. 18°29.3'N, 63°24'W. 686-723 m; 5 foot

Blake trawl; July 23, 1969.-2 specimens, UMML 30.8328;

John Elliott Pillsbury sin. P-1255, 17°18'N, 78°32'W. 23-

622 m; 10 foot otter trawl; July 14, 1970. — 4 specimens,

UMML 30.8155; John Elliott Pillsbury sta. P-1261,

17°13'N. 77°50'W, 595-824 m; 10 foot otter trawl; July

15, 1970.-14 specimens, USNM 95399; 9 specimens,

USNM 614087; Albatross sta. 2751, 16°54'N, 63°12'W,

1,257 m; large beam trawl; November 28, 1887. — 1 spec-

imen, MCZ 7597; Blake sta. 163. 16°03'10"N. 6r52'20"W,

1,407 m; Januarx 20, 1879—1 specimen, UMML 30.8154;

John Elliott Pillsbury sta. P-861, 12°42'N, 61°05.5'W,

18-744 m; 10 foot otter trawl; July 4, 1969. — 2 specimens,

USNM 94942; Blake sta. 264. 12°03'15"N. 61°48'30"W.

767 m; March 1, 1879—1 specimen, USNM 96876; Al-

batross sta. 2754, ir40'N, 58°33'W, 1,609 m; large beam

trawl; December 18, 1887.— Fragments, BM(NH)

1887.2.9.353; Challenger sta. 120, 8°37'S, 34°28'W, 1,235

m; September 9, 1873. — 11 specimens, USNM 150756;

Albatross sta. 2760, 12°07'S, 37°17'W, 1,864 m; large

beam trawl; December 18, 1887.

Description: Shell small (height of largest specimen 7.2

mm, width 8.2 mm), conical, peripheralK carinate, pol-

ished, white, iridescent under thin outer porcelaneous

layer. Protoconch 375-450 ^m (usually about 425 nm)

in ma.ximum diameter, prominent, glassy. Teleoconch

whorls 7.5-8.0; spire whorls flat, with widely spaced (2-

4 per mm) sigmoid a.xial riblets and fine spiral threads;

sculpture usually strongest near suture and peripher)-,

obsolete medially on whorls 3-6, becoming distinct again

on whorls 7-8; suture distinct but not impressed. Pe-

riphery marked by strong carina, overlain by about 4

spiral threads, rendered strongly denticulate by the axial

riblets, visible on all whorls. Base almost flat, often smooth

medially, otherwise with strong spiral cords and obscure

transverse threads in striae between spiral cords; sculp-

ture stronger near umbilicus. Umbilicus wide, approxi-

mately 24% maximum shell diameter, bounded periph-

erally by strong, tuberculate spiral cord, .\perture

subrectangualr, lips thin; outer lip bisinuate. with pe-

ripheral spur, and with wide, moderately deep. U-shaped

posterior sinus, abapertural edge of which slightly flared;

basal lip with wide, shallow, sinus, with weakly flared

edges, apex in outer third of lip; columella straight, slight-

ly oblique, distinctK inflated medially, terminating in

rounded boss.

Animal occupies approximately 2 whorls, with esti-

mated length of 8-10 mm. Epipodium prominent, flap-

like, bearing 4 (probably 5) epipodial tentacles, ante-

Page 64

THE NAUTILUS, Vol. 101, No. 2

riormost and posteriormost rather long, slender, middle

2 (or 3) much shorter. Esophagus running posteriorly

from buccal area, making sharp ventral turn at level of

last intestinal loop, then running posteriorly along ventral

margin of right intestinal tract. Intestine very long, prob-

ably 15-20 mm total length when complete, running

forward along left side of animal, forming series of tight

convolutions and loops in anterior 2-3 mm, abruptly

crossing to right side approximately 2 mm posterior to

mantle edge, making short, tight dorsal loop before run-

ning posteriorly in series of strong sinuations; at some

point posterior to preserved sections, intestine makes sharp

U-turn, running anteriorly along left side of animal, the

2 sections closely appressed posteriorly, then separated

by intervening structures anteriorly; about 3 mm pos-

terior to mantle edge it makes 2 tight right-left loops,

then runs straight along left side for about 2 mm, turning

sharpK right for about 0.5 mm, finally running anteriorly

for final 1.5 mm; anus lying just posterior to edge of

mantle on right side of animal. A 3 mm long fragment

from near posterior reach of intestine contained some

loops of intestine and/or esophagus ventrally and an

ovate, 1.75 mm long organ that occupied the same rel-

ative position as the kidney of Segnenzia cf. sp. S. eritima

(see Quinn, 1983b: fig. 34), but was solid and evenly

rounded, rather than delicate and somewhat lobulate as

in the Seguenzia species. No other features were ob-

served because of poor preservation. Radula lost during

preparation for SEM.

"The operculum is circular, very thin, concave, of

about four whorls. The radula , . . has a rhachidian with

a triangular cusp finely denticulated on the sides, a wide

lateral with an inwardly directly [sic, directed] triangular

cusp denticulated on both sides, and several (6 or 7)

marginals, flat and rather narrow, denticulated along

most of the outer edge but on the inner edge onlv near

the tip" (Bayer, 1971:124).

Measurements: Lectotype [BM(NH) 1887.2.9.351; here

designated]: 6.3 mm high, 5.9+ mm wide. Largest spec-

imen: 7.2 mm high, 8.2 mm wide.

Type-locality: NW of St. Thomas, Virgin Islands, Chal-

lenger sta. 24, 18°30'30"N, 65°05'30"W, 713 m (here

designated).

Remarks: All four species of Hadroconns are very sim-

ilar morphologically. Hadroconns sibogae (Schepman,

1908), from Makassar Strait, off Celebes Island, Indo-

nesia, differs from the three western Atlantic species in

that it totally lacks spiral sculpture on the upper whorl

surface, except for "one or two spiral elevated striae . . .

on part of the upper whorls (Schepman, 1908:62-63).

The three western Atlantic species are more difficult to

distinguish from each other, especialK because of the

iiitraspecific variation of shells of H. altus. Discussions

and analyses of characters distinguishing //. altiis from

//. watsoni (Dall, 1927) and the undescribed species will

be presented in a future paper revising the western At-

lantic Hadroconns.

Intraspecific variation in shells ol H. altns is extensive.

The height: width (h:vv) ratio varies from 0.68 to 1.07

(x = 0.85 ± 0.10; N = 22); the lower the ratio, the more

distinctly concave the spire outline becomes. In a manner

similar to that of the spiral sculpture above the periphery,

the basal spiral cords tend to become obsolete on the

medial part of the base. This smooth area varies from

15% to 47% (x = 28.5%) of the umbilicus-periphery

distance. In a few specimens [BM(NH) 1887.2.9.351-352,

and UMML 30.8018, 30.8151, and 30.8155], the basal

spiral cords are all strong and separated by strong grooves.

These specimens also had the highest h:w ratios (0.97-

1.07) and some of the smallest protoconchs (375-400 ^m),

but these values were not significantly different from

those of the lower spired forms (Student s t; P < 0.05).

Hadroconns altns is known from the Bahamas, Straits

of Florida, Gulf of Mexico, Yucatan Channel, the entire

Antillean Arc, and oft Brazil. Bathymetric occurrence is

about 500-700 m in the northern Straits of Florida, and

generally deeper than 1,000 m elsewhere, with the deep-

est record (2,276-2,360 m) in the southern Straits of

Florida. Depths of the three lots with live-collected spec-

imens were 805-722 m (UMML 30.8328, P-1255). 1 ,200-

800 m (MNHN, Alaniinos sta. 66-A9-15), and 1,390-

1,414 m (UMML 30.8150, G-964). Hadroconns altns thus

seems to inhabit depths considerabK greater than those

in which either of the other western Atlantic species live

(H. watsoni: approximateU' 430-805 m: Hadroconns n.

sp.: 329-512 m; personal observations).

Rotellenzia new genus

Basilissa: Watson, 1879:.593 {partim); 1886:96 (partim).—

Schepman, 1908:61 (par/im).— Cotton, 1959:189 {par-

tim).

Seguenzia Group II: Quinn, 1983b:728 {partim).

Type-species: Basilissa lampra Watson, 1879; here des-

ignated.

Gende

Feminine.

Diagnosis: Shell of moderate size, depressed conical,

weakly carinate peripherally, fragile, brilliantly irides-

cent under very thin outer porcelaneous layer, color

brassy; spire almost flat-sided, sutures weakK impressed;

whorls with 2 weak carinae at periphery, visible onl\ on

last whorl, with numerous spiral threads above peripheral

cords, strongest on first 3 whorls, obscure subsequently;

axial sculpture of low riblets on first 1.5 w horls, thereafter

almost absent; base weakly convex, with numerous spiral

threads, umbilicate; umbilicus wide, defined by strong,

smooth spiral cord; aperture rhomboidal; lips thin with

broad, \'-shaped posterior sinus, and broad, ver\ shallow.

U-shaped basal sinus; anterolateral sinus, it present, prob-

ably narrow, shallow and U-shaped; columella thin, very

weakly sigmoid, edentate.

Remarks: The shell of the t\ pe-species of this genus is

most similar to those of species of Segnenziella Marshall,

1983. Rotellenzia lampra. however, lacks the strong mid-

whorl and peripheral carinae which characterize Se-

J. F. Quinn, Jr., 1987

Page 65

/

^

A;*

N^lfea^

Figures 6-8. Rolellenzia lainpra (Watson, 1879). Apical, apertiiral, and basal views of holot\pe of Basilissa lampra. BM(NH)

1887.2.9.348, height 7.5 mm. maximum diameter 12.2 mm. Figures 9, 10. Asthehjs miinda (Watson, 1879), Apertiiral and basal

views of holotvpe of Basilissa munda, BM(NH) 1887.2.9.350, height 3.0 mm, maximum diameter 3.3 mm.

guenziella. Moreover, if Schepman's (1908: text fig. 1)

illustration of the radula of R. lampra is accurate, the

odd structure of the cusps of the rhachidian and laterals

further separates the two genera. However, the two gen-

era undoubtedK are closely related, and, on the evidence

of the radula, both are more closely allied to Seguenzia

Jeffreys, 1876, than to other genera with similar shell

shapes, such as Carenzia Quinn, 1983. If the similarities

of shells hold between Rotcllenzia and Seguenziella, a

narrow, U-shaped anterolateral labral sinus probably ex-

ists. However, the chipped lip of the holotype of R.

lampra prevents direct observation of this feature, and

the growth lines give no additional indication, a situation

also found in Scgiienziella.

Etymology: From the Latin diminuati\e of rota, a wheel,

and Seguenzia, a genus of Seguenziidae.

Rolellenzia lampra (Watson, 1879)

(figures 6-8)

Basilissa lampra Watson, 1879:593; 1886:97, pi. 7, fig. 5. —

Schepman, 1908:61, text fig. 1.— Cotton, 1959:189.

Seguenzia lampra: Quinn, I983b:728, fig. 45.

Material examined: 1 specimen, BM(NH) 1887.2.9.348

(holotvpe); Challenger sta. 246, 36°10'N, 178°00'E, 3,749

m; July 2, 1875.

Description: Shell of moderate size (height 7.5 mm,

width 12.2 mm), depressed conical, weakly carinate pe-

ripherally, umbilicate, thin, iridescent under very thin

porcelaneous layer, brass-colored. Protoconch large, about

500 ^m in maximum diameter, about 1 whorl. Teleo-

conch whorls 5.25, spire whorls flat to weakly convex;

first 3 whorls with fine, sharp spiral threads, one at mid-

whorl strongest, subsecjuent whorls with spirals subequal

in strength, all becoming weaker over last 2 whorls;

threads number 19 near aperture; last whorl with 2 strong,

smooth spiral cords, anterior one peripheral, posterior

one close above and along which suture runs, interspace

narrow, weakly concave; axial sculpture of low, sharp

collabral riblets on first 1.5 whorls, thereafter rapidly

disappearing, except near suture where they remain ev-

ident as short, comma-like folds. Base weakly convex,

umbilicate, with 15 spiral cords (increasing rapidK near

aperture to 25), outer 3 rather strong, separated by con-

cave interspaces bearing 3-4 fine spiral threads near ap-

erture, middle 75% of base with 9 broad, flat spiral cords

separated by shallow striae, inner 3 cords strong, sharp,

separated b\ concave interspaces with fine, sharp trans-

verse riblets. Umbilicus wide, about 30% maximum shell

diameter, funnel-shaped, walls weakly concave, smooth

except for growth lines. Aperture trapezoidal; outer lip

thin, posterior sinus shallow, broadly \'-shaped, apex in

posterior 25% of whorl; basal lip thin, basal sinus a wide,

very shallow sinuation of lip, apex located in abaxial

quarter of base; columella thin, weakly concave in adap-

ical half, weakK con\ex in abapical half Operculum

unknown. Radula with lanceolate rhachidian, cusp not

reflected, finely denticulate along cusp base, unarmed

Page 66

THE NAUTILUS, Vol. 101, No. 2

Figures 11-14. SEM micrographs of Asf/if/ys munda (Watson, 1879) from Porcupine st&iion 22, USNM 859916. II. Apertural

view, X 45.5. 12. Oblique apical view, x 42. 13. Protoconch, x 126. 14. Oblique basal view, x 45.5.

distally; lateral with wide, triangular base, long, unre-

flected cusp on proximal side, finely denticulate along

distal edge well back from tip; inner marginal sickle-

shaped, edentate.

Holotype: height 7.5 mm, width 12.2

Measurements:

mm.

Type-locality: NW of Midway Island, Hawaiian Is-

lands, Challenger sta. 246, 36°10'N, 178°00'E, 3,749 m.

Remarks: See under generic remarks.

Asthelys new genus

Seguenzia: Jeffreys, 1877:320 {partini).

Rasilissa Watson. 1879:59.3 (partim): 1886:96 (parhm).— Quinn,

1983b:729 (partim).

Type-species: Basilissa tiiunda Watson, 1879; here des-

ignated.

Gender: Feminine.

Diagnosis: Shell small, conical, |5eripherall\ bicariiiate,

umbilicate, nacreous under thin outer porcelaneous la\-

61 white; protoconch large; first 0.5 whorl lacking spiral

sculpture, subsequent whorls with strong cord abo\e pe-

riphery and strong peripheral cord, together forming

weakly bicarinate periphery, weak to strong spiral cords

on base, and strong, smooth or pustulate circumumbilical

cord; a.xial sculpture of obscure, sigmoid folds and growth

lines; surface microsculpture of microscopic, shallow

punctae; base weakly conve.x; umbilicus narrow, funnel-

like; aperture subquadrate; labral sinuses 2, wide, shal-

low; columella straight or weakly concave. Radula un-

known.

Remarks: Aslhclys most closeK' resembles Thelyssina

Marshall, 1983. Shells of both genera are conical with

almost flush sutures, lack a midw horl carina, spiral cord,

or angulation on the first teleoconch whorl immediately

follow ing the termination of the protoconch, lack strong

coUabral and spiral microsculpture above the whorl pe-

riphery, and have a narrow, funnel-like umbilicus. The

type-species of Asthelys differs from that of Thelyssina

by lacking a trochoid tip and terminal rim on the pro-

toconch, having minute punctae instead of vermiculate

microsculpture on the first two spire whorls (although T.

sterrha Marshall, 1983, also has punctations, fide Mar-

shall, personal communication), ha\ ing a bicarinate rath-

er than unicarinate periplier\ , ha\ ing a distinct posterior

J. F. Quinn, Jr., 1987

Page 67

shell sinus, persistence of the initial spiral cord on all

teleoconch whorls, and lacking a strong parietal callus.

At least two other species may also be assigned to Asthe-

lys: Basilissa simplex Watson, 1879, and an undescribed

Antarctic species (Marshall, personal communication).

Etymology: .\nagram of Thelyssa. a genus of Seguen-

ziidae

Asthelys miinda (Watson, 1879)

(figures 9-14)

Seguenzia carinata Jeffreys, 1877:320 (partim).

Basilissa mimda Watson, 1879:596; 1886:99, pi. 7, fig, 7,—

Quinn, 1983b:729, [Son Basilissa munda Barsanova, 1966:

150 (misidentiflcation).]

Material examined: 1 specimen, USNM 859916 [(para-

lectotvpe of Carcnzia carinata (Jeffre\'s, 1877)]; Porcu-

pine sta. 22, 56°08'N, 13°34'W, 2,311 m; July, 1870.— 1

specimen, BM(\H) 1887.2.9.350 (holotvpe); 'c/ia//r»gfr

sta. 85, 28°42'N, 18°06'W, 2,058 m; August 29, 1873.

Description: Shell \er\ small (height of holotype 3,0

mm, width 3.3 mm), conical, weakly bicarinate periph-

erally, narrowly umbilicate, thin, iridescent under thin

outer porcelaneous layer, white. Protoconch with irreg-

ular microsculpture, about 350-375 /um maximum

diameter, of about 1 whorl, lacking terminal rim. Te-

leoconch whorls 4.75; spiral sculpture absent on first half-

whorl; fine spiral thread appears on second half-whorl,

located at abapical fifth of whorl, gradually strength-

ening to become subequal to peripheral cord; peripheral

cord visible only on last whorl, forming bicarinate pe-

riphery with upper spiral cord; axial sculpture present

on all whorls, consisting of e.xtremely obscure sigmoid

folds, most apparent as undulations of spiral cords; sur-

face microsculpture of microscopic, extremeK- shallov\'

punctae generally arranged in spiral pattern. Base weak-

ly convex, with 11 spiral cords, innermost strongest, with

8 pustules, and sigmoid transverse rugae and minute

punctae. Umbilicus narrow, about 14^ of maximum shell

diameter, funnel-shaped, walls smooth except for axial

growth lines. Aperture subquadrate; outer lip thin, with

very wide, shallow, U-shaped posterior sinus, apex lo-

cated above midwhorl; basal lip thin, with ver\' wide

and shallow basal sinus, apex at abaxial third of base;

columella almost straight, very weakly concave above,

very weakly convex below, slightly thickened, edentate.

Type-locality: W of Palma, Canarv Islands, Challenger

sta. 85, 28°42'N, 18°06'W, 2,058 m'.

Remarks: Asthelys munda is most similar to A. simplex

(Watson, 1879), but A. munda is smaller, relatively

broader, lacks a subsutural spiral cord, and has weaker

basal spiral cords, pustulate circumumbilical cord, and

less oblique aperture. The specimen from the Porcupine

Expedition is a juvenile (figures 9-12) from the syntype

lot of Carenzia carinata (Jeffreys, 1877). The localit)' of

this specimen (NW of Ireland) extends the known range

of the species northward more than 2,600 km, indicating

a distribution throughout the northeastern Atlantic in

depths of about 2,000 m,

ACKNOWLEDGEMENTS

Special thanks are due to Bruce A, Marshall (National

Museum of New Zealand) for providing me with results

of his work on New Zealand seguenziids, particularly on

Asthelys, and for reading a previous version of this paper.

His willingness to share such information has made it

possible to avoid certain errors of commission, as well as

omission. I thank the two anonymous reviewers for their

constructive comments. I thank the following for allow-

ing access to specimens in the collections under their

charge: Richard S, Houbrick and the late Joseph Rose-

water, USNM; Gilbert L, Voss, UMML; Philippe Bou-

chet, MNHN; and John Taylor and Kathie Way, BM(NH ).

Some of the specimens examined for this paper were

collected during the National Geographic-Universitv- of

Miami Deep-Sea Expeditions supported by a grant from

the National Geographic Society, Washington, D.C, Ar-

thur E. Bogan (ANSP), David K. Camp, and Jennifer

Wheaton (Florida Department of Natural Resources, Bu-

reau of Marine Research) commented on a draft of this

paper. The SEM micrographs of Hadroconus alius were

made by Lana Tester (formerly Florida Department of

Natural Resources, Bureau of Marine Research); those

of Asthelys munda were made b>' the author under a

Morris K. Jacobson Scholarship award from the Astronaut

Trail Shell Club, Melbourne, Florida. Sally Kaicher pro-

vided photographs of the types. A portion of this paper

was a part of a dissertation submitted to the Universitv

of Miami in partial fulfillment of the requirements for

the degree of Doctor of Philosophy, and constitutes a

scientific contribution from the Rosenstiel School of Ma-

rine and Atmospheric Science, Universit>' of Miami, Cor-

al Gables, Florida.

LITERATURE CITED

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Reinhold, New York, NY, p. 663,

Barsanova, N, G, 1966, K nachozhdeniyu glubokovodnikh

predstavitelei semeistva Seguenziidae (Gastropoda, Pro-

sobranchia) v Tikhom Okeane, [On the finding of deep-

sea representatives of the family Seguenziidae (Gastrop-

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Okeanologii 81:144-152.

Baver, F. M, 1971, New and unusual mollusks collected by

R/V JOHN ELLIOTT PILLSBURY and R/V GERDA in

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Boss, K. J, 1982. Seguenziidae, /n; Parker, S. P. (ed.). Synopsis

and classification of living organisms. Vol, 1, McGraw-

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Clarke, A. H. 1962. Annotated list and bibliography of the

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Cossmann, M. 1888, Catalogue illustre des coquilles fossiles

de I'Eocene des environs de Paris. III. .Annales de la Societe

RoNale Malacologique de Belgique 23:3-324.

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Cotton, B. C. 1959. South Australian Mollusca. — Archaeo-

gastropoda. Handbook of the Qora and fauna of South

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Dall. \V. H. 1881. Reports on the results of dredging, under

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9(2):33-144.

Dall, VV. H. 1885. List of marine Mollusca comprising the

Quaternary fossils and Recent forms from .American lo-

calities between Cape Hatteras and Cape Roque including

the Bermudas. United States Geological Survey, Bulletin

24:1-336.

Dall, W. H. 1889a. Reports on the results of dredging, under

the supervision of .Alexander .\gassiz, in the Gulf of Mexico

(1877-78) and in the Caribbean Sea (1879-80), by the U.S.

Coast Survey steamer "Blake", Lieut-Commander C. D.

Sigsbee, U.S.N. , and Commander J. R. Bartlett, U.S.N,,

commanding, XXIX. Report on the Mollusca. Part 2, Gas-

tropoda and Scaphopoda. Bulletin of the Museum of Com-

parative Zoology 18:1-492.

Dall, W. H. 1889b. A preliminary catalogue of the shell-

bearing marine mollusks and brachiopods of the south-

eastern coast of the United States. Bulletin of the United

States National Museum 37:1-221.

Dall, W. H. 1890. Scientific results of explorations by the U.S.

Fish Commission steamer "Albatross". VII. Preliminary

report on the collection of Mollusca and Brachiopoda ob-

tained in 1887-88. Proceedings of the United States Na-

tional Museum 12:219-362.

Dall, W. H. 1927. Small shells from dredgings off the southeast

coast of the United States by the United States Fisheries

steamer "Albatross" in 1885 and 1886. Proceedings of the

United States National Museum 70(2667):1-134.

Fischer, P. 1885. Manuel de conchy liologie et de paleonto-

logie conchyliologique, ou historie naturelle de mollusques

vivants et fossiles. F. Savy, Paris, p. 689-896.

Goryachev, V, N. 1979. K sisteme glubokovodnikh mollyus-

kov semeistva Seguenziidae (Gastropoda). [On the system

of the deep-sea molluscan family Seguenziidae (Gastrop-

oda).] In: Likharev, I. M. (ed.). Molluscs. Main results of

their study. Abstracts of communications. Zoological In-

stitute, Akademiya Nauk SSSR, Leningrad, p. 70-71.

Jeffreys, J, G. 1877. New and peculiar Mollusca of the Eu-

limidae and other families of Gastropoda, as well as of the

Pteropoda, procured in the Valorous' Expedition. .Annals

and Magazine of Natural History (4)19:317-.339.

Johnson, C. W. 1934. List of marine Mollusca of the Atlantic

coast from Labrador to Texas. Proceedings of the Boston

Society of Natural History 40(l):l-204.

Keen, A. M. and L. R. Cox. 1960. [Margaritinae]. In: Moore,

R. C. (ed). Treatise on invertebrate paleontology. Part I,

Mollusca 1. Geological Society of America, University of

Kansas Press, Lawrence, KS, p 1249-125 1.

Marshall, B .A 1983 Recent and Tertiar> Seguenziidae (Mol-

lusca: Gastropoda) from the New Zealand region. New

Zealand Journal of Zoology 10:2.35-262.

Martens, E. von. 1881. Mollusca. Zoological Record 16:93 p.

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Part 2: Scaphopoda, Gastropoda, Amphineura, Cephalop-

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Okutani, T. 1982 Rediscoveries of an abyssal trochid, Basi-

lissa superba Watson from the south of Japan. Venus,

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Pilsbry, H. A. 1889. Trochidae, Stomatiidae, Pleurotomari-

idae, Haliotidae. Manual of Conchology. Series 1, Volume

11. Conchological Section, .Academy of Natural Sciences,

Philadelphia, PA, p. 519.

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Miami Deep-Sea Expeditions. 130. The systematics and

zoogeography of the gastropod family Trochidae collected

in the Straits of Florida and its approaches. Malacologia

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guenziidae Verrill, 1884. Bulletin of the American Mala-

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(Gastropoda: Prosobranchia) with the descripion of a new-

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1884 (Gastropoda: Prosobranchia). I. Summary and eval-

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THE NAUTILUS 101(2):69-74, 1987

Page 69

Good Hosts and Their Guests: Relations Between Trochid

Gastropods and the Epizoic Limpet Crepidula adunca

Geerai J. Vermeij

Department of Zoology

University of Maryland

College Park, MD 20742

USA

Richard B. Lowell

Department of Zoology

Uniyersit)' of Alberta

Edmonton, Alberta

Canada

Linda J. Walters

Department of Biology

University of South Carolina

Columbia, SC 29208, USA

Jessica A. Marks

Department of Zoology

University of Washington

Seattle, WA 9S195, USA

ABSTRACT

The suspension-feeding cal\ ptraeid limpet-like gastropod Cre-

pidula adunca (Sowerby ) is found chieQ> on the shells of other

gastropods in the temperate northeastern Pacific. In the San

Juan Islands (Washington, US.\), its only host is the trochid

Calliostoma ligatum (Gould), Experiments in the laboratory

showed that Crepidula was protected from predation by the

sea-star Leptasterias hexactis by virtue of its close fit on the

host shell and by the effective escape response of Calliostoma

to sea-stars. The added weight of Crepidula (up to 24*7 of

combined weight of guest and host) reduced escape speed and

increased the time required for hosts to right themselves after

falling in an aperture-up orientation.

INTRODUCTION

Intimate associations between host and guest species are

widespread among bottom-dwelling marine organisms.

Such associations — parasitisms, commensalisms, and mu-

tualisms— may arise for any of several reasons. In the

first place, there are apt to be benefits to the guest. These

include a greater and more predictable food supply,

greater protection from enemies, and shelter from harsh

ph\sical conditions. The suitabilit\ of a given species as

host depends on its abundance, defenses against potential

enemies, and extent to which it is able to provide benefits.

If the presence of the guests improves the host's own

performance in coping with surroundings, selection in

favor of traits facilitating the association would be es-

pecially strong.

The present paper is the first in a projected series on

the evolution of one widespread but little studied type

of intimate association among marine species, that of

epizoic limpet-like gastropods living on the shells of other

invertebrates. We report here on the association of the

temperate northeastern Pacific calyptraeid limpet-like

gastropod Crepidula adunca (So\\erb\ ) (hereafter known

as Crepidula) with two trochid gastropod hosts, Callios-

toma ligatum (Gould) and Tegula funebralis (A. Adams)

(hereafter known as Calliostoma and Tegula. respec-

tively). Specifically, we investigated the host distribution

of Crepidula. the predators of Calliostoma, the effect of

Crepidula on the antipredatory performance of its host

in the laboratory, and some factors that render Callios-

toma an especialK' suitable host for Crepidula.

This research was carried out during May and June,

1986, as part of a field course on functional morphology

and evolution given at the Friday Harbor Laboratories

(Friday Harbor, Washington, USA) by A. R. Palmer and

the senior author, with assistance from R. B. Lowell.

MATERIALS AND METHODS

The distribution of Crepidula among hosts was assessed

at several localities in Washington and California. E.x-

perimental work was conducted with Calliostoma and

Crepidula from Lime Kiln Light (San Juan Island, Wash-

ington) and with Tegula and Crepidula from Tatoosh

Island (Washington).

As a first step in the identification of potential pred-

ators of Calliostoma, a field collection of all available

"dead shells (either empty or occupied by hermit crabs)

was made at Lime Kiln Light. Shells were categorized

as intact, lethally broken (the apex removed, the lip bro-

ken back, or one or more holes of irregular shape through

the shell wall), or drilled, \e.\t, Calliostoma with epizoic

Crepidula were maintained in the laboratory with three

species of predator that commonly co-occur with Cal-

liostoma in the lower intertidal zone. Three crabs (male

Cancer ore gonensis Rathbun, 29.0-44.2 mm in carapace

width) were maintained for 9 days with 10 Calliostoma

each bearing an epizoic Crepidula. Another 30 Callios-

Page 70

THE NAUTILUS, Vol. 101, No. 2

toma with epizoic Crepidula were kept w ith 15 Nucella

lamelloaa ((jirielin), a drilling muricacean gastropod, for

4 days. The sea-star Leptasterias hexactis (Brandt) in

preliminary trials was offered Calliostoma with epizoic

Crepidula as well as Crepidula that had been removed

from their hosts and allowed to attach to the floor of an

acjuariuni before sea-stars were introduced.

.\11 subsequent work involving predation concentrated

on how Calliostoma protects Crepidula from predation

b\ Leptasterias. In the first experiment, 20 Crepidula

ranging in apertural length Irom 6.5 to 9.5 mm were

removed from their original hosts and transplanted onto

10 living Calliostoma and 10 empty Calliostoma. All

Crpp!c/(//a-bearing Calliostoma (18.7-21.8 mm in lon-

gest dimension) were then glued to square pieces of Plex-

iglas, 3 cm on each side, with Z-Spar (Koppers Company

Inc., Pittsburgh, PA 15219, USA), a quick-setting un-

derwater epoxy-putty, and placed in an aquarium with

30 Leptaserias (48-78 mm in diameter) for 7 days. Glue

was applied to the shell base in such a way that the

aperture was oriented obliquely to the floor of the aquar-

ium, so that the snail's foot was able to attach to the

substratum and capable of reaching the shell's apex.

Moreover, the foot v\as free to reach the shell s apex, as

would be the case in free-roaming individuals. If differ-

ences in the mortality of Crepidula did appear between

those on living and empty Calliostoma, they would be

accounted for by traits of the host's soft parts and not

by the locomotor performance of the host or the precision

of the Crepidula' s fit on the host. None of the trans-

planted Crepidula had as close a fit on the new host as

they did on their original hosts.

In order to evaluate how the locomotor performance

of Calliostoma affects Crepidula, we ran a laboratory

trial for 2 days with 10 glued Calliostoma (16.9-20.8

mm long), 10 free-roaming Calliostoma (16.2-25,0 mm

long), and 18 Leptasterias. Each Calliostoma bore a

Crepidula (8.5-12.0 mm long) which was found on it in

the field and which therefore conformed precisely to the

shell contour of the host.

The presence of Crepidula potentially influences the

escape of the host from slow-moving predators like sea-

stars. In this study, we focused on three factors of im-

portance in the escape of Calliostoma and Tegula from

sea-stars, and on how Crepidula affects the host s escape

performance in the laboratory. These were (1) the speed

oi flight, (2) orientation of the host on the aquarium floor

after the snail is dropped from a vertical surface (a sim-

ulation of what happens when the snail drops from the

substratum upt)n contact with a sea-star), and (3) the

time needed to right the shell if the snail fell with ap-

erture (and foot) facing up.

Escape speed of Calliostoma and Tegula was mea-

sured in an acjuarium at a temperature of 11.5-13.0 °C.

.\fter 2 min of acclimation to the aiiuarium, each snail

was touched for 3 sec with the tube foot of the sea-star

Pycnopodia helianthoides (Brandt) on the cephalic ten-

tacles. The snail then reared up, rotated 180°, and began

its escape. The speed of escape was measured from the

time that flight began. Traces of the snail's movements

were drawn on a clear plastic sheet that was taped to

the underside of the clear Plexiglas aquarium. String was

then placed along the trace, cut, and measured according

to the path follov\ ed by the snail for each interval of 30

sec until the snail encountered the w all of the aquarium.

Tests were conducted on snails naturalK lacking Cre-

pidula, snails with naturally fitted Crepidula whose im-

mersed weight in sea-water was less than 10% of the

combined weight of host and guest, and snails with nat-

urally fitted Crepidula w hose immersed weight account-

ed for 10% or more of the total weight of host and guest.

Orientation of hosts after falling from a vertical sur-

face was assessed for individuals w ith and without Cre-

pidula. Snails held as if the\' were clinging to a vertical

wall of an aquarium were touched with a tube foot and

then allowed to fall through 31.5 cm of water to the

bottom. Orientation upon landing w as considered to be

either aperture-up or aperture-dow n. Three trials were

done on each snail.

The time required for snails landing aperture-up to

right themselves after a fall was measured for Callios-

toma and Tegula with and without epizoic Crepidula.

After unsuccessful trials with bottoms of sand, small grav-

el, and smooth Plexiglas (substrata on which the snails

were unable to right themselves), a 6 mm plastic mesh

was used as the substratum on which righting was as-

sessed. The holes in the mesh were smaller than the

smallest linear dimension of the snail's foot. Righting was

divided into two phases: (1) attachment of the foot to

the substratum, and (2) placement of the shell over the

foot.

RESULTS

Host Specificity of Crepidlla

At the sites we have investigated, Crepidula adunca were

found as adults only on the shells of other animals, chieflN'

gastropods (Table 1). The trochid Calliostoma ligatum

was the only host at San Juan Island, On the outer Pacific

coast of Washington and British Columbia, we have also

seen C. adunca on Amphissa columbiana (Dall), Sear-

lesia dira (Reeve), and Tegula funehralis. Tegula is not

found at San Juan Island, but Amphissa and Searlesia

are common there; \et they lacked epizoic Crepidula.

Calliostoma, some with epizoic Crepidula, is common

on the outer Pacific coast together with the other hosts.

In the vicinity of Monterey, California, C. adunca is

apparentK restricted to Tegula funehralis (see also Put-

nam, 1964). Juvenile C. adunca are found on adult Cre-

pidula as well as on the other hosts mentioned.

Crepidida was the only organism found living on the

shells of living Calliostoma. B\ virtue of its ability to

extend the foot over the whole shell surface (Harrold.

1982), Calliostoma is apparently able to prevent settle-

ment of epizoans other than Crepidula (figure 1). Shells

of Calliostoma occupied b\ hermit crabs ha\e a variety

of epizoans, including small limpets (Tectura scutum

G J. Vermei] et ai. 198"

Page 71

Table 1. Occurrence of Crepidnla adunca on hosts at various

sites in the northeastern Pacific

Eschscholtz and Acmaea mitra Eschscholtz), barnacles,

serpulid pol\chaetes, and the bryozoan Tiibulipora sp.

Tegula does not extend its foot up to the shell ape.x, and

apparently cannot prevent settlement of epizoans on the

outer shell surface. Of 22 living T. funebralis from Ta-

toosh Island, seven (32?o) bore Crepidula and nine (41%)

bore serpuiids, barnacles, or coralline red algae. Three

individuals bearing Crepidula also had other epizoans

growing on the shell. Crepidula itself also carried various

combinations of corallines, br\ozoans, and serpuiids.

Predators of Calliostoma

An analysis of "dead" shells of Calliostoma from Lime

Kiln Light suggested that drilling is not a cause of death,

and that breakage ma\ be less common than those forms

of death that leave the shell intact. Of 78 shells collected,

61 (78%) were intact and 17 (22%) were lethally broken.

The proportion of broken shells may have been under-

estimated owing to the fact that apical fragments may

have been lost quickly from the supply of shells available

to hermit crabs.

Laboratory trials indicated that the crab Cancer or-

egonensis is a potential predator of both Calliostoma

and Crepidula. Over a 9-da\ period, three out of 10

Calliostoma. as well as three out of 10 Crepidula epizoic

on the victims, were eaten bv the three male crabs. The

Figure 1. Crepidula adunca epizoic on Calliostoma ligatum

from Lime Kiln Light, San Juan Island, Washington. Photo-

graph by R.B.L.

broken shells of Calliostoma closely resembled the dam-

aged "dead" shells collected at Lime Kiln Light.

None of the 30 Calliostoma maintained with 15 Su-

cella lamellosa for 4 days was eaten. This finding cor-

roborated the field evidence that Calliostoma was not

drilled.

Several sea-stars include Calliostoma in their diet and

leave the shell intact after the prey is consumed. They

include Pycnopodia helianthoides (Shivji et ai, 1983),

Orthasterlas koehleri (Mauzey et ai, 1968), Stijlasterias

forreri (Mauzey et al.. 1968), Pisaster giganteiis (Har-

rold, 1982), and Leptasterias hexactis (Hoffman, 1981).

Calliostoma has well-developed escape responses to these

sea-stars (Hoffman, 1981; Harrold, 1982). We concen-

trated our work on Leptasterias. which attacks its prey

by everting the stomach into the aperture and digesting

the flesh externally. Not only is Leptasterias abundant

in the low intertidal habitat of Calliostoma, but in pre-

liminary trials this sea-star ate naturally fitted guests as

well as their hosts that had been confined with Leptas-

terias in mesh cages under water. We suspected that a

good fit of the guest on the host, together with the hosts

escape reaction, protected Crepidula from predation by

sea-stars.

Trials with 10 Crepidula-hearing free-roaming Cal-

liostoma kept with six Leptasterias for 7 days resulted

in the predation of four hosts and no guests. In another

trial, three Leptasterias during a 16-hr period ate four

of eight Crepidula that had been allowed to attach to

the floor of an aquarium after being remo\ed from their

hosts.

Imprecisely fitted Crepidula apparently gained no

Page

THE NAUTILUS, Vol. 101, No. 2

Table 2. Escape speeds of Calliostoma ligatum in response

to contact with the sea-star Pycnopodia. Snails that were used

either bore naturally fitting Crepidula or were found in the

field to lack epizoic Crepidula.

Table 3. Effect of Crepidula on landing orientation of hosts

after the latter fall from a vertical surface.

Category

Trials

Escape speed

(cm/sec)

with SD

Crepidula lacking

Crepidula less than 10% of

total weight

Crepidula greater than 10%

of total weight

0.34 ± 0.037

0.32 ± 0.022

(1.27 ± 0.070

protection from sea-stars b\ their association with living

Calliostoma if the latter were unable to escape. In the

experiment with transplanted Crepidula on living and

empt) Calliostoma. mortaiitv' of Crepidula was the same

(five of 10 individuals) whether the host shell was empty

or contained a living snail. In addition to preying on

Crepidula, Leptasterias ate seven of 10 living Callios-

toma.

The effects of a close fit and of the host s escape were

further demonstrated by the pattern of attack by sea-

stars in the experiment with immobile (glued) and free-

roaming CrepiV/u/a-bearing Calliostoma. After the first

9 min of the experiment, nine of 10 free-roaming hosts

had already crawled from the floor of the aquarium to

just above the surface of the water on the vertical walls

of the aquarium. Of the 10 Calliostoma attacked by

Leptasterias during the first 4 hr of the experiment, eight

were immobile and onl\ two were free-roaming. This

difference was significant at the 0.05 level (two-by-two

contingency test). After 2 days, Leptasterias had con-

sumed seven of 10 glued Calliostoma, three of 10 free-

roaming Calliostoma, and none of the Crepidula.

Escape was not the only defense of Calliostoma against

Leptasterias. Of the 42 cases of subjugation of Callios-

toma by Leptasterias that we witnessed, at least 19 (45%)

were unsuccessful. The latter figure is almost certainly

an underestimate, because we were unable to monitor

the animals continuously. In the 19 unsuccessful attacks,

Leptasterias was found to be humped over the prey and

to have extruded the stomach into the aperture in the

usual way, but the sea-stars were unable to push aside

the tightly fitting operculum of the retracted gastropod.

When the sea-stars released the Calliostoma, the latter

remained withdrawn for some time before resuming nor-

mal crawling activity. The average time required for

Leptasterias to subdue and consume Calliostoma was 2

days.

Effect of the Guest on the Host

Crepidula could have several detrimental effects on its

host. In the first place, it adds substantial weight to the

animal. Crepidula accounted for a mean of 10.2 ± 5.3%

of the immersed weight of the host and guest combined

(range 1.0-23.8%', n = 57). For Tegula and Crepidula.

the mean contribution of Crepidula s immersed weight

was 7.3% (range 0.9-16.0%, n = 7).

The added weight of Crepidula could reduce the lo-

comotor performance of Calliostoma during escape at-

tempts from sea-stars. Compared to individuals lacking

Crepidula. Calliostoma with a load of Crepidula greater

than 10% of total immersed weight moved 20% less rap-

idly upon being touched by a tube foot of Pycnopodia

(p < 0.05, see Table 2). Calliostoma with a moderate

load (less than 10% of immersed weight) of Crepidula

moved at intermediate speeds, but did not differ statis-

tically from the heavily weighted or the Crepidida-iree

snails.

Data in Table 3 on landing orientation indicate that

Table 4. Effect of epizoic Crepidula on the time required by hosts to right themselves after landing aperture-up Differences

between Calliostoma with and without Crepidula were statistically significant at p < 0,001 for both the foot-attachment (first) and

shell-positioning (second) phases of righting. For Tegula. differences for the first iihase and for the righting process as a whole were

significant at p < 0.02.

Time in seconds with SD

Category

Trials

Phase 1

Phase 2

Calliostoma with Crepidula

Calliostoma without Crepidula

Tegula with Crepidula

Tegula without Crepidula

180

132

21

28

82 ± 185

34 ± 21

774 ± 257

527 ± 420

6.2 ± 11

1.2 ± 1.2

0.24 ± 0.77

0 84 ±0 44

G. J. Vermeij ct ai, 1987

Page 73

epizoic Crepidula had an inconsistent effect on its host.

The chance of the host s landing aperture-down, en-

abling the snail to begin crawling aw ay sooner, was great-

er for Crcpiclula-hfdnng CaUioHtoma than for indi\id-

uals whose Crepidula were removed, but snails naturally

lacking Crepidula had the same rather high probability

of landing aperture-down as did individuals with epizoic

Crepidula. Tegula w ith Crepidula were less likeK to fall

aperture-down than were indi\iduals without epizoic

Crepidula.

The time required for hosts to right themselves after

landing in an aperture-up position was significantK

greater in individuals bearing Crepidula than in those

same individuals from which the Crepidula had been

removed (Table 4). In Calliostoma. this was true for both

the foot-attachment and the shell-positioning phases of

the righting process, whereas in Tegula the pattern was

due entirely to the first (foot-attachment) phase. The

presence of Crepidula increased the time of righting by

factors of 2.5 and 1.5 in Calliostoma and Tegula. re-

spectively.

DISCUSSION

Our study of Crepidula adunca showed that this species

is more or less specialized to live as an epizoan on the

shells of living gastropods. Hoagland (1977a) reported

that the species has also been collected from the surfaces

of subtidal stones, but we have never found C. adunca

on substrata other than the shells of gastropods and a few

hermit crabs despite extensive dredging on all tvpes of

bottom in the San Juan Islands. In its apparent restriction

to the shells of other animals, C. adunca resembles the

tropical Eastern Pacific C. incurva (Broderip), but the

latter species is found on many gastropod hosts as well

as on hermit crabs (Vermeij, unpublished data) whereas

C. adunca is apparently absent from most potential host

gastropods with which it lives in the lower intertidal and

subtidal zones. The eastern North American C. convexa

(Sa\ ) ma\' live on the shells of gastropods (Hoagland,

1977b), but it is more common on shells occupied by

hermit crabs (Karlson & Cariolou, 1982; Shenk & Karl-

son, 1986), and also frequently adheres to stones and sea-

grasses (Hoagland, 1977a, b). Among species that have

been ecologicalK characterized, therefore, C. adunca

ranks as one of the most specialized w ith respect to the

range of substrata occupied.

As sedentarv- filter-feeders, adult Crepidula would in

general be highK- vulnerable to many kinds of predators,

as well as to competitors and physical calamities. Species

that characteristically live on exposed surfaces of stones

or rocks tend to be large, thick-shelled, and sometimes

spiny, whereas most species (except C. incurva) living

on the outer or inner surfaces of shells tend to be small

and thin-shelled. That shells provide a refuge from pred-

ators is suggested by our data. Although C. adunca that

were artificially removed from their host readiK fell

victim to Lcptasterias, epizoic individuals were rarely

eaten by this predator by virtue of the effective escape

responses of Calliostoma ligatum, one of its chief hosts.

A similar benefit of living on the shells of mobile trochids

(Austrocochlea constricta Lamarck) was demonstrated

by Mapstone et al. ( 1984) in experiments with the grazing

epizoic lottiid limpet Patelloida niufria (Hedley) in New-

South Wales, but in this case the chief predator was the

muricacean gastropod Morula marginalba (Blainville).

Our results may be criticized for having been obtained

under controlled laboratorv conditions rather than in the

field. We believe, however, that the types of field ex-

periment used by Mapstone et al. (1984), in which lim-

pets w ith and w ithout host snails were maintained with

and without predators in cages, introduce the same kinds

of limitations that are imposed by conditions in the lab-

oratory. Another objection — our lack of replication of

some of the experiments — was forced upon us by insuf-

ficient time.

We do not know if Crepidula gains an)- substantial

protection from its hosts in encounters with other pred-

ators. Preliminar>' trials showed that Calliostoma as well

as epizoic Crepidula were attacked successfullv bv the

crab Cancer oregonensis.

Our data indicate clearly that the presence of Cre-

pidula decreased the locomotor performance of hosts

during escape attempts from sea-stars. To what extent

the decrease in escape speed and the increase in the time

required for righting the shell after a fall place Callios-

toma and Tegula at greater risk to predation in the field

cannot be determined at present. In a similar case, Schmitt

et al. (1983) showed that when the Californian trochid

Norrisia norrisi (Sowerby) attempted to escape from Pi-

saster giganteus, its escape velocity was decreased in the

presence of the epizoic barnacle Megabalanus califor-

nicus, and that this decrease resulted in a higher success

rate for Pisaster.

It is likely that weight rather than drag is responsible

for the decrease of the snails locomotor performance in

the presence of epizoic Crepidula. At the relatively low

velocities of most gastropods, drag is low (Palmer, 1980).

Crepidula ma} benefit from its association with snails

in wa>s that we did not investigate. The fact that Cal-

liostoma ligatum is capable of cleaning its shell and

laying down a thin film of mucus on the outer shell

surface suggests that settlement of potential competitors

such as bryozoans, barnacles, and algae is usually pre-

vented. How juvenile Crepidula are able to settle and

stay on Calliostoma when the latter's foot is extended

over the shell is not known. It is also possible that the

mucus may contribute to, or help trap, Crepidula s food

supply. A possible benefit of Crepidula for its hosts is

that it increases the effective size of the host, so that

potential predators would have greater difficulty in sub-

duing the host. A potential disadvantage of the associa-

tion to Crepidula is that the guest is exposed to desic-

cation and is prevented from feeding when the host

crawls out of water. A similar disadvantage was noted

by Mapstone et al. (1984) for Patelloida mufria on Aus-

trocochlea constricta. but in that case the limpet tended

to be found chiefl\' on the underside of the host's shell

Page 74

THE NAUTILUS, Vol. 101, No. 2

where the guest is less at risk to desiccation, whereas in

the present instance the guest often occurs on the upper

surface of the shell. Adult (female) Crepidula are sed-

entary, and are therefore incapable of moving to the

safer underside of the host.

Compared to other species in its size range, Callios-

toma ligatum is the fastest among the low intertidal

gastropods in the San Juan Islands (Miller, 1974). This

fact suggests that other potential hosts would pose greater

risks for epizoic Crepidula. We do not know why Sear-

lesia and Amphissa serve as hosts on the outer Pacific

coast whereas they are not occupied by Crepidula in the

San Juan Islands. Searlesia seems to be avoided by sea-

stars, and it would therefore seem to be a good host for

Crepidula wherever it occurs; but the animal is very

slow, it extends higher into the intertidal zone than does

Calliostoma, and its shell is extensively grazed by small

patellacean limpets.

Although mobility of the host may be an important

attribute protecting epizoic Crepidula and some other

limpets such as Patelloida nnifria, it may have little to

do with the choice of hosts by other epizoic limpets. What

these other attributes might be and how they vary geo-

graphically are interesting questions for future investi-

gations.

ACKNOWLEDGEMENTS

We thank the Friday Harbor Laboratories for providing

research facilities and a stimulating environment, and

Elaine Hoagland and Ronald Karlson for reviewing the

manuscript.

LITERATURE CITED

Harroid, C. 1982. Escape responses and prey availability in

a kelp-forest predator-prey system. American Naturalist

119:132-135.

Hoagland, K E. 1977a. Systematic review of fossil and Recent

Crepidula and discussion of evolution of the Calyptraei-

dae. Malacologia 16:353-420.

Hoagland, K. E. 1977b. A gastropod color polymorphism: one

adaptive strategy of phenotypic variation. Biological Bul-

letin 152:360-372.

Hoffman, D. L. 1981. Defensive responses of marine gastro-

pods (Prosobranchia, Trochidae) to certain predatory sea

stars and the dire whelk, Searlesia dira (Reeve). Pacific

Science 34:231-243.

Karlson, R. H and M. A Cariolou. 1982. Hermit crab shell

colonization by Crepidula cotivexa Say. Journal of Exper-

imental Marine Biology and Ecology 65: 1-10.

Mapstone, B. D., A. J. Underwood, and R. G. Creese. 1984.

Experimental analyses of the commensal relation between

intertidal gastropods Patelloida mufria and the trochid

Aiistrocochtea constricta. Marine Ecologv Progress Series

17:85-100.

Mauzey, K. P., C. Birkeland, and P. K. Dayton. 1968 Feeding

behavior of asteroids and escape responses of their prey

in the Puget Sound region. Ecology 49:603-619.

Miller, S. L 1974. Adaptive design of locomotion and foot

form in prosobranch gastropods. Journal of Experimental

Marine Biology and Ecology 14:99-156.

Palmer, A. R. 1980. Locomotion rates and shell form in the

Gastropoda: a re-evaluation. Malacologia 19:289-296.

Putnam, D. ,\. 1964. The dispersal of young of the commensal

gastropod Crepidula adunca from its host, Tegula june-

bralis. The Veliger 6(Suppl.):63-66.

Schmitt, R. J., C. W. Osenberg, and M. G. Bercovitch. 1983.

Mechanisms and consequences of shell fouling in the kelp

snail, Norrisia norrisi (Sowerby) (Trochidae): indirect ef-

fects of Octopus drilling. Journal of Experimental Marine

Biology and Ecology 69:267-281.

Shenk, M. A. and R. H. Karlson. 1986. Colonization of a shell

resource by calyptraeid gastropods: tests of habitat selec-

tion and preemption models Journal of Experimental Ma-

rine Biology and Ecology 99:79-89.

Shivji, M., D. Parker, B. Hartwick, M. J. Smith, and N. A. Sloan.

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star Pycnopodia helianthoides (Brandt, 1835). Pacific Sci-

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THE NAUTILUS 101(2):75-79, 1987

Page 75

Distribution, Abundance, and Movement Patterns of Shoreline

Chitons of the Caribbean Coast of Mexico

Charles W. Randall

Robert F. Martin

Texas Memorial Museum and

Department of Zoology

The Universit\ of Texas at Austin

Austin, TX 78705, USA

ABSTRACT

Observations of relative numbers, wet weight, distribution, and

movements of Chiton squamosus and Acanthopletira granu-

lata were made during 1983 and 1984 along unsubmerged,

wave-washed portions of the rocky shorelines of Akumal and

Tulum, Quintana Roo, Mexico. Incidental, less detailed data

are presented for Chiton marmoratus, Ceratozona squalida.

and Chiton tuberculatus. Chiton sqtiamosus was most abun-

dant at Tulum in exposed, wave-washed situations well above

mean sea level; A, granulata occurred in lower, more protected

areas, and was most common in shore-margin pools at Akumal

Chiton marmoratus was less common than the former two

species, and usually occurred in areas exposed to wave action

in three morphotypes, Ceratozona squalida and C. tubercu-

latus were uncommon above mean low water level. Numerical

densities of C. squamosus ranged from 0.3/m- to 13.9/m-,

depending upon habitat type; biomass densities ranged from

0.3 g, m- to 28.2 g/m-. Numerical density of A. granulata

ranged from O.l/m- to 16.4/ m-, biomass densit\ from 0 g/m-

to 54.9 g/m-. Jul) and December size distributions and total

numbers are presented for C. squamosus and A. granulata at

four subsites of each major research area. Numbers of C. squa-

mosus at three Tulum subsites were reduced following severe

summer storms. Movements of both C. squamosus and A. gran-

ulata were primarily nocturnal, although some individuals of

each were active diurnalK'. Nocturnal movement b\ individual

chitons usualK w as discontinuous. Comparison of total distances

moved with total displacements from original sites suggested

tendencies to travel within restricted areas.

INTRODUCTION

Although the marine invertebrates of the Caribbean Sea

have been studied with considerable intensity, reports

dealing with the invertebrate fauna from the north-

western shores of these waters are relatively scarce. Re-

search on chitons reflects this situation well; although a

number of works on various aspects of the biologv of

West Indian species exist (see Glynn, 1970, for refer-

ences), the species of the western shores of this sea have

been relatively neglected and t\ pically are represented

casualK in publications dealing with general moUuscan

faunas (e.g., Weisbord, 1926; Jaume, 1946; Hidalgo, 1956;

Yokes, 1983). Here, we list the chitons of the rocky shore-

line of a restricted segment of the eastern coast of the

Yucatan Peninsula and discuss in preliminary fashion

various aspects of the ecology of Chiton squamosus and

Acantbopleura granulata, the two most common chitons

there.

STUDY AREA AND METHODS

Our study sites are at Akumal (20°24'N, 87°18"W) and

Tulum {20°13'N, 87°26"W), Quintana Roo, Mexico. In

this area, sandy embayments alternate with rocky

headlands of dark limestone, eroded remnants of Pleis-

tocene reefs. Fringing, live reefs lie from several hundred

to nearly a thousand meters offshore. During much of

the \ear, the easterly tradewind sweeps the coast; vari-

ations in water level at the shoreline appear to be more

a function of wind velocity and direction than that of

the minor semidiurnal tidal changes (less than 0.3 m;

data from tide tables for Key West, Florida, USA cor-

rected for Belize City, Belize, 325 km S Akumal) that

occur along this coast.

At Akumal, a shallow (maximum depth 1.5-4 m), cres-

centic bay approximately 1 km broad and 500 m deep

is protected at its seaward boundary by a living coral

reef. The flanking, northern margin of the bay is a flat,

weathered Pleistocene reef-limestone headland, frag-

mented at its seaward fringe, and rising shallowly from

sea level at its outer edge to only several meters above

sea level at its junction with the forebeach. In 1983, six

pools (subsites) were selected from along the seaward

margin of this headland for surveys of numbers and

densities, and for observations of movements of chitons;

only data from four of these are presented here. All were

within 10 m of the sea margin and were filled and drained

by wave action for at least part of each da\'. In some

areas of these pools, chitons were exposed to conditions

of drying and direct sunlight. Crude measurements along

the longest axis of each pool and along the longest axis

perpendicular to this were taken; in addition, two pools

Page 76

THE NAUTILUS, Vol. 101, No. 2

were measured more accurately and were drawn to scale

on graph paper to allow calculations of chiton densities.

Pool 1 measured 7.0 x 4.6 m; Pool 3, 1 1.6 x 1.8 m; Pool

5, 7.3 X 4.6 m; Pool 6, 4.3 x 2.7 m. Water depth within

pools usually ranged from less than 0.3 m to approxi-

mately 0.8 m. During the storms of July 2-18, 1983,

pools frequentK were totalK' immersed by the sea for

several hours to longer than one da> . Various pools were

surveyed for size class, numbers, and species of chiton

on July 20 and December 15, 1983; other, less detailed

surveys were made prior and subsequent to these dates.

.\t the Tulum site, the coast is sublinear; steep lime-

stone cliffs (remnants of the Pleistocene reef) rise directly

from the sandy bottom, or from a litter of very large to

small breakdown boulders. A fringing reef lies approx-

imately 0.5 km offshore. Horizontally, much of the cliff

base and breakdown is below water for most of the day

and wave splash usually precludes drying. A zone of

multicellular reddish- to greenish-brown adherent algal

vegetation coats the lowest portions of most cliff faces

and breakdown rubble from the sandy bottom extending

upward from several cm to 1.2 m. On this (windward)

coast, the vertical limit of this vegetation probably is the

product of a number of physical (wind direction and

intensity, mean and extreme low tide, etc. ), and possibly,

also, biotic factors (Duggins and Dethier, 1985).

At Tulum, the plane of the upper level of this algal

zone served as our major vertical reference point. Lack-

ing calm conditions during the stud>, we could not de-

termine tidal stands here with accuracy, but feel that

the zone's upper level more nearly approximates mean

high, rather than mean low, water level. Chitons were

far more numerous above (up to 1.8 m above the sandy

substrate) than within this vegetation, and only those

above and a few easily visible within the upper 30 cm

of the zone were counted in our surveys. Constantly

submerged areas were not examined for presence of chi-

tons during this stud\ .

Seven subsites were selected along cliff bases and

breakdown rubble; only data for four of these are pre-

sented here. Subsite 1 was a moderate-sized, deeply pit-

ted boulder of irregular shape, separated by 1 m from

an adjoining rock. Its base was completely submerged to

a depth of 0.3-0.6 m at most times; its top usually ex-

tended 0.6-0.9 m above sea level, and its circumference

at the upper macro-algal limit was approximately 12.2

m. .Approximately 75% of its exposed (all but its upper-

most) surface was inhabited by chitons. Subsite 2 was an

undercut cliff face just N of Subsite 1; approximately

14.3 m of its length was surveyed for chitons. Subsite 5

was a very large, slab-sided boulder separated from other

rock surfaces by at least 3 m of sand; most (all but the

farthest backside) of its lower circumference was inhab-

ited by chitons; this 28.7 m was surveyed. Subsite 7 was

an isolated rock just S oi Subsite 5 and surrounded b\

sand; 12.2 m of its circumference were surveyed. Subsites

1-7 were surveved on Julv 20 and 21 and December 13,

1983.

Prior to survey and movement studies, six size classes

of chitons were erected as follows: Class 1, those less than

1.27 cm from anterior to posterior tips of girdle; Class

2, those from 1.27 to 2.53 cm; Class 3, 2.54-3.80 cm;

Class 4, 3.81-5.07 cm; Class 5, 5.08-6.34 cm; Class 6,

6.35-7.61 cm. To crudely assess biomass, wet weights

were taken for five specimens of each species from each

of the three size classes which held the greatest number

of individuals of that species. Chitons were removed from

substrate, blotted dry with a soft cloth, and weighed to

the nearest 0. 1 g with a Pesola spring balance. .After

weighing, shell plates were removed from an additional

sample of eight formalin-preserved chitons, and weigh-

ings were repeated to determine ratios of wet soft part

weight to total weight. These ratios were utilized in final

calculations of biomass densities.

To investigate movement patterns, indi\ iduals of each

species were marked with small spots of quick-drying

paint and their locations were noted. One to several re-

turn visits were made to determine if movement had

occurred from the original location of each. .\t Tulum

on June 28, six C. squamosus clinging in relatively ver-

tical wave-splashed areas were marked during the period

0545-0750 hr; all were checked near 1700 hr and one

was checked twice additionally at 0700 hr on June 28

and at 0600 hr on June 29. At Akumal on July 18, 1983,

nine A. granulata were marked near 1000 hr and were

checked for displacement from original sites twice sub-

sequently on that date; three additional individuals were

marked at 0215 hr and checked near 1700 hr. .A full

dark to davlight vigil was maintained during the night

of July 28-29, 1983 (Akumal Pool 2, 2015-0545 hr) to

monitor nocturnal movements of both species; a less thor-

ough vigil was undertaken during the night of JuK 1-2,

1984 at .Akumal Pool 3 to gain additional data. On both

nights, movements were checked at 15-min intervals.

Voucher specimens of the fi\e species of chiton en-

countered are deposited in the Recent Invertebrate Col-

lection of the Texas Memorial Museuni-The University

of Texas at Austin: C. squamosus, 1574TX1; .4. granu-

lata. 1574TX2; Chiton marmoratiis, 1574T\3, 1574T.\4,

1574TX5; Ceratozona squalida. 1574TX6; Chiton tii-

berculatus, 1574TX7.

RESULTS

Distribution: Chiton squamosus is most numerous in

areas exposed to wave action; at Tulum, most adhere to

vertical surfaces above the level of the multicellular algae

and are kept moist by wave splash or inundation. Here,

Acanthuplcura granulata occurs in lower, more shel-

tered or concealed locations, among the cre\ ices of cliff

breakdown rubble, closer to, and sometimes within the

algal zone. Chiton marmoratiis occurs in three color

morphs (.Abbott, 1974) and at lower frequenc> at Tulum

than C. squanwsus and .A. grauuUita, but still is relativ cK

common; it represents less than 20% of the entire chiton

population here. The reddish morph of C. marmoratus

is far less common here than the light and dark morphs.

The distribution of this species is similar to that of C.

C. W, Randall and R. F. Martin, 1987

Page 7'

Table 1. Numbers of Chiton sqtiamosus and Acanthopleura grantilata at four Tulum subsites on July 20 and December 13, 1983.

December surveys not performed at Subsites 2 and 5.

squamosus, but somewhat closer to the top of the algal

zone. Ceratozona squalida occurs within, and occasion-

ally above, the zone of algae and forms less than 1*^ of

the non-submerged population visible at this site. Chiton

luberciilatus is rare; only two were encountered during

our surveys.

On the relatively exposed vertical rock faces and rub-

ble at Tulum, C. squamosus was more common than A.

granulata (table 1), although the cryptic distribution of

A. granulata here results in some degree of underesti-

mation of its abundance. In the shelf-margin pools at

Akumal, A. granulata was far more common than C.

squamosus (table 2). No additional species of chiton were

observed here. Just beyond the seaward entries and spill-

ways of these pools, in alternately exposed and inundat-

ed, heavily surf-swept areas not surveyed, C. squamosus

were more numerous, and A. granulata decreased in

frequency.

Biomass: Mean \\et weights per most common size

classes (x ± SE) of C. squamosus were: Class 2, 0.68 ±

0.08 g; Class 3, 1.98 ± 0.23 g; Class 4, 6.28 ± 0.21 g.

Those for A. granulata were: Class 3, 4.06 ± 0.35 g;

Class 4, 8.94 ± 0.29 g; Class 5, 11.40 ± 0.92 g. Ratios

of wet soft part weight to total v\ eight were: C. sqiia-

nwsus. 0.50; A. granulata, 0.43.

Density: Numerical density data for both species were

calculated (table 3) and reflect those presented previously

for numbers (tables 1, 2) at both sites. Inter-subsite dif-

ferences in numerical density (table 3) are more pro-

Table 2. Numbers of Chiton squamosus and Acanthopleura granulata at four .Akumal subsites on July 20 and December 15,

1983.'

' December surveys not performed at Subsites 3 and 5.

Page 78

THE NAUTILUS, Vol. 101, No. 2

Table 3. Numerical density (individuals/ m-) and biomass

density' (g, m'; in parentheses) for Chiton squamoHus and

Acanthopleura granulata at Tulum and Akiniial .subsites on

July 20 and December 13 or 15, 1983

' Biomass densities are based only on size classes 2, 3, and 4 for

C, squamosus and 3, 4, and 5 for A. granulata. hence are

conservative (see tables 1 and 2 to assess unincluded specimens),

- Tulum surveyed December 13; Akumal, December 15,

nounced at Tulum than at Akumal due to the greater

amount of habitat diversity (degree of exposure versus

shelter) here; biomass densities in g/m- also reflect this

relationship (table 3),

Size distribution: At both Tulum and Akumal, individ-

uals of size Class 4 usually were the most comnnon A.

granulata during July and December surveys (tables 1,

2), At Akumal, individuals of Class 3 were the most

common C. squamosus in both surveys (table 2); at Tul-

um, C. squamosus of Class 3 were most common during

three surveys, while those of Class 4 were most common

in three other surveys (table 1),

Storm effects: A number of storms with severe easterly

winds struck our sites during the period of July 2-18,

1983; that on July 16 was particularly severe. Percentage

losses of C, squamosus at three Tulum subsites between

JuK 7, the date of preliminarv surveys at several subsites,

antl JuK 20, 1983 (table 1), the date of our main survey,

were: Subsite 2, 32%; Subsite 5, 27%; Subsite 7, 29%. By

December 13, 1983, the population of C, squamosus at

Subsite 7, one of two subsites at Tulum surveyed then

(table 1), exceeded that of the July 20 survey by 71%

and that of the July 7 preliminary survey by 20%. Pop-

ulations of A, granulata at these sites were too small to

use in loss estimates (table 1),

Movements: Diurnal displacements of C, squamosus

marked on June 29 were as follows: Chiton 1) 0715-1700

hr, 35,6 cm; 2) 0715-1700 hr, 0 cm; 3) 0750-1705 hr,

10,2 cm; 4) 0750-1705 hr, 5.1 cm; 5) 0750-1715 hr, 11.4

cm; 6) 0545-0700 hr, 48.3 cm; 0700-1705 hr, 91.4 cm;

1705-0600 hr, 170 cm. Diurnal displacements of A. gran-

ulata marked on July 18 were as follows: 1) 1000-1350

hr, 7,6 cm; 1350-1710 hr, 0 cm; 2) 1000-1350 hr, 2,5

cm; 1350-1710 hr, 99,1 cm; 3) 1000-1350 hr, 0cm; 1350-

1710 hr, 0 cm; 4, 5, 6) 1015-1430 hr, 0 cm; 1430-1725

hr, 0 cm (all three individuals); 7) 1415-1710 hr, 7,62

cm; 8, 9) 1415-1710 hr, 0 cm. General observations of

C. squamosus at Tulum and of A, granulata at Akumal

during census periods also indicated that individuals of

the former species were more likely to be in motion

during daylight than those of the latter.

Distributive statistics for total time observed, total dis-

tance moved, and rate of travel are presented by species

and size class for the 1983 nocturnal movement survey

in table 4. Individuals of both species moved discontin-

uously; some remained motionless for more than an hour

between bouts of movement; none were active contin-

uously through the night (table 4). Sample sizes were

small and did not permit confident comparisons between

species or size classes. Displacement ol individual chitons

from place of initial observation to place of final obser-

vation usually was considerably less than 30% of total

distance traveled; this suggested either a lack of strongly

directional movement or a weak tendency to remain

within a home "range". In 1984, distances travelled and

rates of travel for 6 C. squamosus were approximately

50% those of 1983; those for A. granulata were less than

33% of those in 1983.

Table 4. Distributive statistics for nocturnal movements of Chiton squamosus and Acanthopleura granulata at ,\kumal Subsite

2 on July 28-29, 1983, during 2015-0545 iir.

.•\ 15 min period m w hicli motion occurred was scored as full 15 nun of motion; tiuis time in motion is an overestimation of actual

activitv.

C. W, Randall and R. F. Martin, 1987

Page 79

DISCUSSION

Few works of direct ecological bearing exist for com-

parison with this study (Glynn, 1970; Kangas & Shep-

herd, 1984; Duggins & Dethier, 1985; Otaiza k Sante-

llces, 1985). Glynn (1970) found A. granulata to be the

chiton that occurred highest on the shore in Puerto Rico

as did Lewis (1960) at Barbados; these authors did not

discuss C. squamosus. At Tulum, when the shoreline

structure permitted comparisons, A. granulata occupied

a physical niche similar to those reported by Lewis (1960)

and b\ Glynn (1970), but o\erlapped approximately the

lower 0.3 m of the habitat of C. squamosus. which oc-

curred considerably higher and was considerably more

numerous at the study site here (table 1). At Akumal,

the study site was not comparable physically with those

at Puerto Rico, Barbados or Tulum, but A. granulata

occurred in greater numbers than C. squamosus (table

2) in situations that were more protected from wave

action. Here, but not at Tulum, A. granulata occurred

in numerical densities (table 3) approaching those re-

ported by Glynn (1970), suggesting that the presence of

C. squamosus may serve to limit the numbers or modify

(toward crypticity) the distribution of A. granulata on

Tulum's vertically disposed shorelines. At our sites (table

3), neither chiton reached densities of the four most

common intertidal chitons studied in Chile by Otaiza

and Santelices (1985), but the average sizes of each of

those four species were considerably smaller than those

of each of ours (tables 1, 2). The range of densities of a

variety of subtidat Australian chitons examined by Kan-

gas and Shepherd (1984), with a single exception, fell

within that of densities of C. squamosus and A. granulata

at our study sites (table 3). Chiton marmoratus was con-

siderably more numerous at the Tulum site than at Glynn's

Puerto Rican stud\ area (1970) and, on the unsubmerged

portions of the shoreline at Tulum, occurred higher than

A. granulata. rather than lower, as at Barbados (Lewis,

1960). Both Chilean (Otaiza & Santelices, 1985) and Aus-

tralian (Kangas & Shepherd, 1984) chitons also displayed

the species-specific vertical habitat stratification char-

acteristic of Caribbean sites.

Following hurricanes that struck Turrumote Reef,

Puerto Rico, in 1963 and 1967, Glynn (1970) noted 46%

and 41% diminutions in numbers of C. tuberculatus and

A. granulata. respectiveh', in 1968 — reductions similar

to those observed in C. squamosus at Tulum following

severe summer storms. Size distributions (table 1) do not

elucidate the process of population recovery at Tulum

Subsite 7, but suggest migration of adults from other

areas less than 3 m distant.

As reported previousK- b\ Glynn (1970) for .4. gran-

ulata and C. tuberculatus in the eastern Caribbean, A.

granulata and C. squamosus from our study area, fed

(indexed by movement) primarily nocturnally, and dis-

played only weak homing abilities.

ACKNOWLEDGEMENTS

We thank the following for their assistance in or support

of the project: Jose Luis Sierra V. and Eric Villanueva

Mukul, Director and Subdirector, Centro Regional del

Sureste, Institute Nacional de Antropologia e Historia;

Victor Segovia Pinto, Jefe de Campo de la Zona Ar-

queologia de Tulum, INAH; and William G. Lyons, Har-

old E. and Emilv H. Yokes, Karsten Tedin, Anthony

Amos, Chris Kitting, Peter E. Scott, James Ponton, Jeffrey

Zeikus, Mark W. Martin, and Nancy G. Lanier Martin.

Partial support for this study was provided by the Texas

Memorial Museum-The Universitv of Texas at Austin.

LITERATURE CITED

.•\bbott, R- T, 1974. .American seashells, 2nd ed. Van Nostrand

Reinhold, New York, 663 p.

Duggins, D, O, and M. N. Dethier. 1985. Experimental studies

of herbivor> and algal competition in a low intertidal

habitat. Oecologia 67:183-191

Glynn, P. W. 1970. On the ecolog\ of the Caribbean chitons

Acanthoplcura granulata Gmelin and Chiton tubercula-

tus Linne: density, mortalit\, feeding, reproduction, and

growth. Smithsonian Contributions to Zoolog) 66:1-21.

Hidalgo, E. 19.56. Algunos moluscos de la Isla de Cozumel,

Quintana Roo, Mexico. Acta Zoologica Mexicana 1:1-16.

Jaume, M. L. 1946. Moluscos marines litorales del Cabo Ca-

toche, Yucatan, Mexico. Revista de la Sociedad Malaco-

logica "Carlos de la Torre ' 4:95-110.

Kangas. M. and S. A, Shepherd. 1984, Distribution and feed-

ing of chitons in a boulder habitat of West Island, South

Australia. Journal of the Malacological Society of Australia

6:101-111.

Lewis, J. B. 1960. The fauna of rocky shores of Barbados,

West Indies. Canadian Journal of Zoology 38:391-435.

Otaiza, R. D. and B. Santelices. 1985. Vertical distribution of

chitons (MoUusca: Polyplacophora) in the Rocky Intertidal

Zone of central Chile Journal of Experimental Marine

Biology and Evolution 86:229-240.

\okes, H. G, 1983. Distribution of shallow-water marine Mol-

lusca, Yucatan Peninsula, Mexico. National Geographic

Society Research Reports 15:715-723.

Weisbord, N. E. 1926. Notes on marine mollusks from the

Yucatan Peninsula, Mexico. The Nautilus 39(3):81-87.

THE NAUTILUS 101{2):80-85. 1987

Page 80

Transfer of Cerithiopsis crystallina Dall to the

Genus Varicopeza Griindel, Family Cerithiidae

(Prosobranchia: Gastropoda)

Richard S. Houbrick

Department of linertebrate Zoology

National Museum of Natural History

Smithsonian Institution

Washington, DC 20560, I'SA

ABSTRACT

The small cerithiid, formerly known as Cerithiopsis crystallina

Dall, is transferred from the family Cerithiopsidae to the famih

Cerithiidae, genus Varicopeza, on the basis of conchological,

radular, and anatomical characters. Varicopeza crystallina is

the first Atlantic species of a previously monot\ pic. Indo-Pacific

genus. It has an extensive, offshore, geographic distribution

throughout the Antilles, Florida, and the Gulf of Mexico.

Key uords: Prosobranchia; Cerithiidae; Cerithiopsis; Vari-

copeza. systematics; Caribbean.

INTRODUCTION

Examination of numerous lots of a small enigmatic cer-

ithiid-like prosobranch, given the specific name crystal-

lina and assigned by Dall (1881:89) with a query to the

genus Cerithiopsis Forbes and Hanley, 1851, has

prompted this paper. "Cerithiopsis" crystallina Dall, 1881

has been dredged in numerous localities throughout the

Antilles, off Florida, and in the Gulf of Mexico. Although

common in some museum collections, it is not a well-

known species and rarely listed in popular shell books.

Dall (1881:89), although initially uncertain of the generic

assignment of this species, later (1889:254) allocated it

to Cerithiopsis with more certitude, and his allocation

has been followed by subsequent authors. Despite Dall's

(1881:90) final referral of this species to Cerithiopsis. he

appears to have been uncomfortable with this assign-

ment, as he compared C. crystallina with other small

dredged cerithiids assigned by Watson (1885) to Bittiuni

Gray, 1847. Dall apparently examined some live-col-

lected material, because he described alcohol-preserved

animals as having well developed eyes and long tentacles,

and a short rounded foot with a circular operculum. He

noted that "the opercular lobe appears to have several

short processes on each side". To my knowledge, no other

published information about this species exists.

A studv of conchological features of "Cerithiopsis"

crystallina indicates that this species does not fit the

criteria defining Cerithiopsis species. Moreover, recent

examination of preserved animals and a study of the

radula w ith scanning electron microscopy ha\ e provided

substantial evidence that C crystallina should not be

considered a member of the Cerithiopsidae. The follow-

ing account presents this evidence and provides a new

description and generic assignment.

MATERIALS AND METHODS

Preserved specimens from Spanish Wells, Eleuthera, ob-

tained from the gut of the starfish Astropecten, were

dissected under a binocular dissecting microscope to study

the operculum, radula, and anatomv'. Scanning electron

micrographs (SEM) were made of the radula, operculum,

and shell on a Zeiss-Novascan-.'30 instrument.

The following abbreviations appear in the text: IRCZM,

Indian River Coastal Zone Museum, Harbor Branch

Oceanographic Institution, Ft. Pierce, Florida; MCZ,

Museum of Comparative Zoologv-, Harvard University,

Cambridge, Massachusetts; MNHNP, Museum National

Figures 1-7. Varicopeza crystallina (Dall). 1. Dead collected specimen from 116 fm, off St. Lucia (USNM 810888), 14.41 mm.

2. Live-collected specimen from 85 fm. Gulf of Mexico, between Mississippi delta and Cedar Keys, Florida (USNM 93763), 17.5

mm. 3. Scanning electron micrograph (SEM) of operculum from specimen off Spanish Wells, Eleuthera, Bahamas (IRCZM 065:

02228), bar = 200 ^m. 4. SEM detail of mid whorl sculpture on specimen from Spanish Wells. Eleuthera, Bahamas (IRCZM 065:

02228), bar = 300 ^m. 5. SEM of protoconch and early whorls of specimen from 100 fm off Barbados (I'SNM 87295), bar = 80

^m. 6. Closeup of early and midwhorls showing sculptural details on specimen depicted in figure 2 (USNM 93763). 7. Detail of

body whorl and aperture from specimen depicted in figure 2 (USNM 93763).

R. S. Houbrick, 1987

Page 81

Page 82

THE NAUTILUS, Vol. 101, No. 2

d'Histoire Naturelle, Paris; USBF, United States Bureau

of Fisheries; USNM, United States National Museum,

National Museum of Natural History, Smithsonian In-

stitution, Washington, DC.

Records and specimens examined: LESSER AN-

TILLES, B.\RB.4.DO.s; MCZ 7406, 13.3 m, R\' Blake, Sta

290; MCZ 7394, 182 m, R\' Hassler, Sta. 1; MCZ 238240

229 m. West Coast, Barbados; USNM 434158, 434164

419146, 419147, 419149, 419150, 434167, 434153, 434154

419148, 430161, 434168, 434159, 434160, 434163, 430162

810910, 810917, all 150-182 m, RV Blake. Sta. 300

Gu.adeloupe: USNM 434155, 1,605 m, RV Blake. Sta

14; St. Lucia: MCZ 7405, 212 m, RV Blake. Sta, 220

USNM 810888, 212 m, RV Blake. Sta. 270, 13°50'15"N

6r03'45"W; Martinique: MCZ 7404, 715 m, RV Blake

Sta. 210; Dominica: MCZ 7402, 583 m, Sta. 176; MCZ

7403, 252 m, Sta. 36; St. Croix: MCZ 7399, 7400, 7401,

210-453 m, RV Blake. Sta. 128, 132, 134, all off St. Croi.x.

GREATER ANTILLES, Cuba: MCZ 7395, 1,472 m, RV

Blake. Sta. 2, off Morro Light, Havana (holotype); MCZ

7398, 823 m, RV Blake. Sta. 51, off Havana; MCZ (no

number), 344 m, RV Blake, Sta. 5, off Santiago; MCZ

(no number), 457 m, RV Atlantis. Sta. 3490, off Havana

i23°ll'N, 81°55'W); USNM 93832, 369 m, RV Blake. Sta.

2131, S of Cuba; USNM 94109, 366 m, RV Blake. Sta.

2135, S of Cuba; Puerto Rico: USNM 161327, Aqadilla.

BAHAMAS: USNM 87304, 618 m, RV Blake. Sta. 2655,

Little Bahama Bank; USNM 216670, RV Albatross. "Ba-

hamas"; IRCZM 065:02228 472 m, RV Johnson. Sta. JSL-

11, 24°52.2'N, 77°15.5'W, off Spanish Wells, Eleuthera;

IRCZM 065:00892, 256 m, RV Gerda, Sta. 638, 26°05'N,

79°12'W, Bimini Banks. FLORIDA: USNM 434151, 219

m, RV Eolis, Sta. 330, off Sambo Reef; USNM 516445,

686 m, RV Eolis. Tortugas; USNM 419006, 119 m, RV

Eolis. Sta. 100, Sand Kev; USNM 419007, 382 m, Eolis,

Sta. 340, off Fowley Light; USNM 419014, 174 m, Eolis,

Sta. 325, off Sand Key; USNM 419010, 155 m, Eolis, Sta.

163, off Sand Key; USNM 419012, 165 m, Eolis. Sta. 319,

off Western Dry Rocks; USNM 419008, 155 m, Eolis.

Sta. 338, off Sand Key; USNM 419009, 155 m, Eolis, Sta.

327, off Sand Key; USNM 434152, 139 m, Eolis, Sta. 161,

Sand Key; USNM 419011, 143 m, Eolis. Sta. 63, off Kev

West; USNM 419013, 146 m, Eolis. Sta. 320, off Western

Dry Rocks. GULF OF MEXICO, USA: USNM 323844,

309 m, USBF Sta. 2400, off Cape San Bias, Florida; USNM

323977, 110 m, USBF Sta. 2402, off Cape San Bias, Flor-

ida; USNM 87297, 91 m, RV Blake. W of Florida; USNM

93998, 309 m, USBF Sta. 2400, between Mississippi Delta

and Cedar Key, Florida; USNM 608531, 121 m, 100 mi

off Ft. Myers, Florida; USNM 83532, Cedar Keys, Flor-

ida; USNM 323834, 309 m, USBF Sta. 2400, off Cape

San Bias, Florida; USNM 323906, 203 m, USBF, off Cape

San Bias, Florida; USNM 93763, 161 m, US Fish Com-

mission Sta. 2403, between Mississippi Delta and Cedar

Keys, Florida; MNHNP, 344-346 m, 28°19'N, 85°44'W;

MCZ I458I9, 24-35 m, 1,5-35 mi off Ft W^alton, Florida;

Mexico: USNM 667771, 168 m, Sta. 1253, Campeche

Banks, off Yucatan.

RESULTS

Description: Shell small, reaching 19 mm in length and

4 mm in width [length measurements of random sample

from throughout geographic range: x = 14.64; sd = 2.49;

range = 10.81-18.04 (n = 13)]. Shell translucent white,

turreted, elongated, comprising up to 25 straight-sided

whorls (figures 1, 2). Shell sculptured with 3 major, nod-

ulose, spiral cords and 14 axial ribs per whorl (figure 4).

Suture deeply impressed. Protoconch-one not seen; pro-

toconch-two large, comprising about 3 whorls (figure 5).

Protoconch-two lacking sculpture except for spiral row

of minute pustules adjacent to suture and 2 very weak,

spiral cords (figure 5). Pronounced sinusigeral notch pres-

ent. Four to 6 juvenile whorls beneath protoconch sculp-

tured with axial ribs only (figure 5). Subsequent early

whorls with 2 beaded spiral cords per whorl that become

3 major spiral cords in later whorls (figure 6). Of these

3, first spiral cord adapical, other 2 cords separated by

weaker, less nodulose spiral cord (figure 4). Bod\ whorl

constricted at siphonal canal and sculptured with 4 raised,

nodulose, spiral cords and 5 or 6 smooth cords on base

(figure 7). Outer lip convex and slightly pinched into

posterior anal notch where it joins penultimate uhorl.

Aperture ovate with wide, distinct anterior canal and

well-developed anal canal (figure 7).

Operculum thin, corneous, circular, externally con-

cave, and with central nucleus; early whorls multispiral,

becoming paucispiral later (figure 3).

Animal with short, wide, bilobed snout and pair of

very long cephalic tentacles. Cephalic eyes large, black.

Mantle edge wavy, edged with tiny papillae strongly

developed at inhalant siphon. Buccal mass relatively large,

bearing small pair of jaws and short taenioglossate radula.

Radula (figure 8) with about 18 rows of teeth. Rachid-

ian tooth (figure 10) with hourglass-shaped basal plate

and cutting edge of 1 large central cusp flanked on each

side by 3 small denticles. Lateral tooth (figures 9, 10)

wide, rhomboidal, with long lateral extension, and cut-

ting edge comprising one sharp, tiny, inner denticle, a

large pointed cusp and 4 or 5 sharp, outer denticles.

Marginal teeth (figure 9) long, hook-like, with sharp tips

comprising central cusp and 3 sharp, inner denticles.

Inner marginal tooth with 2 small denticles on outer side;

outer marginal with smooth outer edge.

Discussion: Although many authors have placed "Cer-

ithiopsis" crystallina in the Cerithiopsidae, this classi-

fication has not realK been satisfactor\ . Cerithiopsids are

characterized b\' small turreted shells having well-de-

veloped, beaded, spiral sculpture, an aperture with a

slight to Daring anterior notch, and a flattened, excavated

shell base. The\' have a pleurembolic proboscis and a

distinctive radula (Marshall, 1978:59-60, figs. 3, 4).

The shell of "Cerithiopsis ' crystallina is not really

comparable with those of cerithiopsid species. The sculp-

ture is more nodular than beaded and more strongly

spiral in composition. The base of the shell is not flattened

or excavated and has a longer, wider anterior canal than

those of cerithopsid species; moreover, the aperture has

R. S. Houbrick, 1987

Page 83

a distinct anal canal and the upper lip flares into a weak

notch where it joins the penultimate whorl.

The short, wide snout does not have the pleurembolic

proboscis of Cerithiopsis species. The tiny taenioglossate

radula of C. crystallina is close to those of members of

the Cerithiidae in overall morpholog\' (see Houbrick,

1978, 1980, 1985).

Dall (1889:254) noted the long cephalic tentacles and

large, black e\ es. His description of the external features

of the animal agrees with m\- observations, but I did not

find the "opercular lobe with "several short processes

on each side", which he mentioned. Dall s words seem

to indicate epipodial tentacles, such as found on Litiopa

Rang and Alaba H. and A. Adams species, but I found

no trace of these structures. The material I examined

appeared to be in good condition; consequentK', I cannot

explain this discrepancy.

The soft anatom\ , radula, and shell of "Cerithiopsis"

crystallina indicate that this species should be removed

from the Cerithiopsidae, superfamily Cerithiopsacea, and

transferred to the Cerithiidae, superfamily Cerithiacea.

Cerithiopsids, although traditionalK- grouped with the

cerithiids on the basis of shell morpholog\ , are now con-

sidered as a separate superfamiK (Kosuge, 1966; Mar-

shall, 1978, 1983). They have been placed in the super-

order Heterogastropoda by Kosuge (1966:297) and more

recently in a new suborder, Heteroglossa, by Haszprunar

(1985). Further evidence separating cerithiopsids from

cerithiaceans has been presented by Healy (1983:212,

1986:195) who has discovered that their euspermatozoan

morphology is quite different from that of other ceri-

thiaceans.

Comparison of the shell and radula of Cerithiopsis

crystallina with those of other small-shelled taxa within

the Cerithiidae shows that it most closely resembles those

of species in the genera Bittium Gra\, Argyropeza Mel-

vill and Standen, and Varicopeza Griindel. Of these three

taxa, the shell shape and sculpture typical of Bittium

species (Houbrick, 1977) does not closely match the over-

all morphology' of C. crystallina. although there is some

resemblance. Protoconch-two of Argyropeza species, as

depicted by Houbrick (1979:8, fig. 2), is different from

that of C. crystallina, as is the sculpture of the adult

whorls and the aperture. Thus, Bittium and Argyropeza

are best excluded as proper generic assignments. Shell

characters such as the strong, nodulose spiral sculpture,

deepK impressed suture, and aperture with a well-de-

fined anal canal and posterior apertural notch all indicate

a morphological resemblance to Varicopeza. a monotyp-

ic taxon previously known only from the Indo-Pacific

and represented bv V. pauxilla (A. Adams, 1854) (see

Houbrick, 1980:528-529, figs. 1, 2). The radula of C.

Figures 8-10. Radula of Varicopeza crystallina (Dall) from

Spanish Wells, Eieuthera, Bahamas (IRCZM 065:02228), 8.

General view of raduiar ribbon, bar = 43 iim. 9. Detail of half

row of teeth, bar = 25 ^m. 10. Detail of rachidian and lateral

teeth, bar = 10 ^m

Page 84

THE NAUTILUS, Vol. 101, No. 2

Figure 11. Geographic distribution ol Varicopeza crystallina (Dall) based on collection data.

crystallina, particularly the hourglass-shaped rachidian

tooth and the dentition and overall shape of the other

teeth, is also similar to that of Varicopeza pauxilla. The

shell of Varicopeza pauxilla is not as large or elongate

as that of C crystallina and has a more strongly defined

posterior apertural notch. The operculum of the two

species differs, that of V. pauxilla has a more eccentric

nucleus and is more ovate than the operculum of V.

crystallina. It appears that C. crystallina most closely

resemf)les Varicopeza, and as I consider the concholog-

ical and opercular differences between the two taxa noted

above to be specific ones, proposal of a new genus to

accommodate C. crystallina is not justified. I think it best

to assign this Western Atlantic species to the genus Var-

icopeza.

The genus Varicopeza was previously know n only from

a single Indo-Pacific species. The addition of V. crys-

tallina to the genus adds a Western Atlantic component

to the geographical distribution of this group. Varicopeza

crystallina has a wide geographic distribution through-

out the Lesser and Greater .Antilles, the eastern Gulf of

Mexico, and around the Florida peninsula (figure 11).

Collection data indicate that it is a common offshore

species having a wide batlnmetric distribution ranging

from 14.8 m to 1,605 m, with a mean depth of 272 m

(n = 41). Nearly all lots comprised a great number of

specimens. The deepest collected specimens are from the

Lesser Antilles, while those from shallowest areas are

from off the west coast of Florida. .\11 specimens have

come from sandy, silty bottoms and although man\ rec-

ords are for empty shells, there were enough live-col-

lected lots (dried animals in shells) to dismiss the possi-

bility that this species occurs in significantK different

bathymetric ranges than indicated. .Specimens (empty

shells) have been found on the beach at Cedar Keys,

Florida,

R. S. Hoiibrick, 1987

Page 85

CONCLUSIONS

Synonymy: The following syiioiiyniy summarizes tiie

taxonomic decisions reached in this paper. A more com-

plete definition of the genus Varicopcza is found in

Houbrick (1980:525-526).

FamiK Cerilhiidae Fleming, 1822

Genus Varicopcza Griindel, 1976

Varicopcza crijstallina (Dall, 1881)

Cerithiopsis ? crystallimi Dall, 1881:89. Holotype: MCZ 7395,

figured type and one paratype; type-locality: RV Blake.

Sta. 2, off Morro Light, N of Havana, Cuba — also Bar-

bados: here restricted to off Morro Light, N of Havana,

Cuba; 1889:254, pi. 20, fig. 3.

Cerithiopsis crystallinum Dall, .-Abbott, 1974:109, fig. 1049G;

Dall and Simpson, 1901424; Warmke and Abbott, 1962:

75; Rice and Kornicker, 1965:119, pi. 2, fig. 9; Boss et al,

1968:95.

ACKNOWLEDGEMENTS

This is contribution No. 181 of the Smithsonian Marine

Station at Link Port, Ft. Pierce, Florida, where most of

this work was done, I thank Paula Mikkelsen, assistant

curator, Indian River Coastal Zone Museum, Harbor

Branch Oceanographic Institution, Ft. Pierce, Florida,

for the loan of preserved specimens in her charge, Drs.

Rudiger Bieler and M. G. Harasewych of the Smithsonian

Institution critically read drafts of the manuscript. I thank

Dr. Kenneth J. Boss, Museum of Comparative Zoology,

Cambridge, Massachusetts, for sending data about t>pe-

material, 1 also thank Julianne Piraino for assistance on

the SEM.

LITERATURE CITED

Abbott, R. T. 1974. American seashells, 2nd ed. New York,

663 p., 24 pis., 6405 figs.

Adams, A. 1854. A monograph of Cerithidea. a genus of

Mollusca, with descriptions of several new species, from

the collection of Hugh Cuming, Esq.: to which are added

descriptions of two new species of Colina. and one of

Donax. Proceedings of the Zoological Society of London

22:83-87.

Boss, K. J., J. Rosewater, and F. A. Ruhoff. 1968. The zoo-

logical ta.xa of William Healy Dall Bulletin of the U.S.

National Museum No, 287:427 p.

Dall, W. H 1881. Reports on the results of dredging, under

the supervision of Alexander Agassiz, in the Gulf of Mexico

and in the Caribbean Sea, 1877-1879, by the L'S. Coast

Steamer "Blake . Preliminary report on the Mollusca. Bul-

letin of the Museum of Comparative Zoologv, Harvard 9:

33-144,

Dall, W. H. 1889. Reports of the results of dredging, under

the supervision of .Alexander Agassiz, in the Gulf of Mexico

(1877-78) and in the Caribbean Sea (1879-80), by the U.S.

Coast Survey Steamer "Blake Lieut -Commander C. D.

Sigsbee, U.S.N. , and Commander J. R. Bartlett, U.S.N.,

commanding Report on the Mollusca. Part 2. Gastropoda

and Scaphopoda. Bulletin of the Museum of Comparative

Zoology, Harvard 18:1-492, pis. 10-40.

Dall, W. H.' and C. T. Simpson. 1901. The Mollusca of Porto

Rico. Bulletin of US, Fish Commission for 1900 1.351-

524, pis. 53-58.

Fleming, J. 1822, The philosophy of zoology or a general

view of the structures, functions, and classifications of an-

imals, etc., 2 vols Edinburgh, no pagination

Forbes, E. and S, Hanley, 1850-51. .\ history of British Mol-

lusca and their shells. Vol. 3. Van Voorst, London, 616 p

Gray, J. E. 1847. The classification of the British Mollusca by

N. E. Leach, M.D. Annals and Magazine of Natural His-

tory 20:267-273.

Griindel, J. 1976, Zur Taxonomie und Phylogenie der BH-

tium-Grnppt- (Gastropoda. Cerithiacea). Malakologische

Abhandlungen Staatliches Museum f iir Tierkunde in Dres-

den 5(3):33-59, 2 pis., 17 figs.

Haszprunar, G. 1985. The Heterobranchia — a new concept

of the phylogen)' of the higher Gastropoda. Zeitschrift fiir

Zoologische Systematik und Evolutionstorschung 23(1):15-

37.

Healy, J. M. 1983. llltrastructure of euspermatozoa of ceri-

thiacean gastropods (Prosobranchia: Mesogastropoda).

Journal of Morphology 178:57-75.

Healy, J. M, 1986. Ultrastructure of paraspermatozoa of cer-

ithiacean gastropods (Prosobranchia: Mesogastropoda).

Helgolander Meeresuntersuchungen 40:177-199.

Houbrick, R. S. 1977. Reevaluation and new description of

the genus Bittium (Cerithiidae). The Veliger 20(2): 101-

106.

Houbrick, R. S. 1978, The family Cerithiidae in the Indo-

Pacific, Part 1: the Genera Rhinoclavis, Pseudovertagus.

Longicerithium, and Clavocerithium. Monographs of Ma-

rine Mollusca No. 1:130 p., 98 pis.

Houbrick, R. S. 1979. Review of the deep sea genus Argy-

ropeza (Gastropoda: Prosobranchia: Cerithiidae). Smith-

sonian Contributions to Zoology No. 321:.30 p., 12 pis.

Houbrick, R, S, 1980. Reappraisal of the gastropod genus

Varicopeza Griindel (Cerithiidae: Prosobranchia). Pro-

ceedings of the Biological Society of Washington 93(3):

525-535.

Houbrick, R, S. 1985. Monograph of the genus Clypeornonis

(Cerithiidae, Prosobranchia). Smithsonian Contributions

to Zoology No. 403:131 p., 62 pis

Kosuge, S, 1966. The family Triphoridae and its systematic

position. Malacologia 4(2):297-.324.

Marshall, B. A. 1978. Cerithiopsidae (Mollusca: Gastropoda)

of New Zealand and a provisional classification of the

family. New Zealand Journal of Zoology 5:47-120.

Marshall, B. A 1983. A revision of the Recent Triphoridae

of southern Australia, Records of the .Australian Museum,

Supplement 2:119 p., 33 figs.

Rice, W. H. and L, Kornicker. 1965, Mollusks from the deeper

waters of the northwestern Campeche Bank, Mexico, Pub-

lications of the Institute of Marine Science, Texas 10:108-

172.

Warmke, G and R T .A.bbott 1961 Caribbean seashells.

Narberth, PA, 346 p , 44 pis.

Watson, R. B. 1884-86. Report on the Scaphopoda and Gas-

teropoda collected by H.M.S. Challenger during the years

1873-1876. In: Report on the scientific results of the voy-

age of the H.MS. Challenger during the years 1873-76

15(42):756 p., 53 pis.

THE NAUTILUS 101(2):86-87, 1987

Page 86

Identity and Status of

Philomycus pennsylvanicus Pilsbry, 1894

(Gastropoda: Pulmonata: Philomycidae)

H. Lee Fairbanks

The Penns\l\aiiia State University

Beaver Campus

Monaca, PA 15061, USA

ABSTRACT

The nomenclatural history of Plulornycus pennsylvanicus Pils-

bry, 1894 is resiewed. As the original specimens were lost and

their description was incomplete, two field trips were conducted

to locate the population from which the specimens were col-

lected. The results of this fieldwork and a study of the Inter-

national Code of Zoological Nomenclature support two con-

clusions: (1) Philomijcus pennsylva7iicus is a nomen nudum

and (2) the slug that Pilsbry began to describe is probably what

is now known as Megapallifera mutabilis (Hubricht, 1951),

INTRODUCTION

The name Philomycus pennsylvanicus was cited by Pils-

bry (1894) for "A maculated species . . .", an extremely

cryptic description. A "Full description ..." was to be

published at a later date. Subsequent usage in fauna! lists

or descriptive papers was limited to Sterki (1907), Dai!

(1916), and Clapp (1920). In his monograph of North

American land mollusks, Pilsbry (1948:767) transferred

the name to the genus Pallifera, and explained the lack

of the promised detailed description, because of "... a

local flood ..." which destroyed the specimens. Pilsbry

(1948) also noted that "It is practically a nude name."

The original collection by Witmer Stone was from

York Furnace, York County, Pennsylvania. Fieldwork to

resample this population and lab work to determine its

identity are reported below.

MATERIALS AND METHODS

Two field trips were conducted to the town of York

Furnace, York County, Pennsylvania (ca. 76°23'18"W,

39°52'25"N) (figure 1 ), the locality given by Pilsbry (1894).

Specimens were collected from trees, logs, under loose

bark, and in the litter around the bases of trees. Data

collected included length (live specimens), mantle pat-

tern, and the appearance of the jaw and reproductive

system. Dissected specimens were drowned first in dis-

tilled \s ater. All material was preserved in 70% ethanol.

RESULTS

A total of 22 slugs were collected on May 22, 1984, after

a rainy night. Dissection revealed that all but one of

these specimens were attributable to the genus Philo-

mycus (presence of dart sac and dart). The reproductive

system of the one specimen was not fully developed, but

the slug did have a ribbed jav\' and was therefore iden-

tified as a species of Pallifera.

An additional 36 slugs were found on July 18, 1984,

also after a night of rain. The mantle pattern on five of

these slugs was different from that of the others. Dissec-

tion demonstrated that all five lacked a dart sac and dart;

the other 31 were all species of Philomycus (dart and

dart sac present). One of the five specimens measured

30 mm in length (crawling), the others were larger (four

specimens, average length crawling 51 mm, range 45-

55 mm). All specimens were mature, i.e.. had fully de-

veloped reproductive systems.

Voucher material, three specimens of Philon}ycus car-

olinianus and one specimen of Pallijcra mutabilis has

been deposited in the United States National Museum

(USNM 853181 and 853182).

DISCUSSION

The International Code of Zoological Nomenclature

(1985) Chapter IV, Article 12 states, "To be available

every new scientific name published before 1931 must

satisf\ the provisions of Article 1 1 and must be accom-

panied by a description or a definition, of the taxon that

it denotes, or by an indication." In addition. Article 10(b)

states, "If publication of the data relating to a new nom-

inal taxon or a nomenclatural act is interrupted and con-

tinued at a later date, the name or nomenclatural act

becomes available only when it satisfies all the relevant

provisions of Articles 10 to 20." Pilsbry stated (1894) that

he would publish a "Full description with anatomical

details ... at a later date. ClearK, publication was in-

terrupted because he intended to publish at a later date,

data ". . . relating to a new nominal taxon . . .". Because

the name did not become available, Pilsbry created a

H. L. Fairbanks, 1987

Page 87

A y*^

£k

York Furnace

Figure 1. A. The location of York Furnace in York County,

Pennsylvania. B. The Y'ork Furnace area, the cross-hatching

represents the search area. Scale bar equals 0.5 km.

nomen niiJiim which has no standing in zoological no-

menclature.

Comparison of the dart-less slugs collected at York

Furnace during this study with the descriptions of the

species of Pallifera and Megapallifcra resulted in the

following identifications. The larger specimens were M.

mutabilis (Hubricht, 1951) (confirmed by L. Hubricht,

personal communication, August 31, 1984); the smaller

specimen was Pallifera josteri Baker, 1939.

Pilsbry (1894) described Plulomycus pennsylvanicus

as "A maculated species having the jaw strongly ribbed.

It is smaller and less distinctly marked than P. cawli-

nianus" (length crawling 70-100 mm). Pilsbry was fa-

miliar with Pallifera dorsalis, then called Philomycus

dorsalis (length crawling 20-25 mm). If P. pennsylvan-

icus was small, i.e.. 30 mm long, it would seem likely

that Pilsbry would have compared it to Pallifera dorsalis.

Smaller than Philomycus carolinianus then probably

meant closer to 70 mm long rather than 25 mm, i.e.,

closer to the size of Megapallifcra mutabilis (length

craw ling ca. 50 mm), not Pallifera fosteri (length crawl-

ing ca. 30 mm).

The results of this study support two conclusions. One,

Philomycus pennsylvanicus is a nomen nudum and

therefore must be dropped from the literature and should

not appear in any future synonymy. Two, it appears

likely that the slug Pilsbry described was what is now

known as Megapatlifera mutabilis (Hubricht, 1951).

ACKNOWLEDGEMENTS

The author thanks Leslie Hubricht for his confirmation

of the identification of specimens, and Walter B. Miller,

Richard L. Reeder, and Russell Doyle for their encour-

agement and critiques of the first draft of this paper.

Financial support was granted by the Faculty Scholar-

ship Support Fund of The Pennsylvania State University.

LITERATURE CITED

Baker, F. C 1939, Fieldbook of Illinois land snails. Illinois

Natural History Survey Manual 2:133-134, Urbana, Illi-

nois,

Clapp, W. F. 1920. The shell of Philomycus carolinianus

(Bosc). The Nautilus 33(3);8:3-S9,

Dall. W. H, 1916. Shells of Mt. Monadnock, N.H, The Nau-

tilus 30:57-58.

Hubricht, L. 1951. Three new land snails from eastern L'nited

States. The Nautilus 65(2):57-59.

International Commission of Zoological Nomenclature. 1985.

International Code of Zoological Nomenclature, 3rd ed.

London, 338 p.

Pilsbry, H. A, 1894. Critical list of mollusks collected in the

Potomac Valle\', Proceedings of the .\cademy of Natural

Sciences of Philadelphia for 1894:11-31,

Pilsbrv, H, .\ 1948. Land Mollusca of North America (north

of Mexico). Academy of Natural Sciences of Philadelphia

Monographs No. 3, Vol. II, Part 2.

Sterki, V, 1907. A preliminary catalogue of the land and fresh-

water Mollusca of Ohio, Proceedings of the Ohio State

Academy of Sciences \'ol, I\', Part 8, Special Papers No.

12:367-402.

THE NAUTILUS 101(2):88-92, 1987

Page

The Diet and Feeding Behavior of Cadulus tolmiei Dall, 1897

(Scaphopoda: Siphonodentahoida)

Perry A. Poon

167 Millbourne Road East

Edmonton, Alberta T6K 1R2

Canada

ABSTRACT

Specimens of Cachihis tolmiei and sediment samples were ob-

tained from Numukamis Bay, Barkley Sound, off Vancouver

Island, British Columbia. The shell length and oral aperture

diameter were measured, and the scaphopods dissected to re-

move gut contents. Live and dead prey items were recorded,

and foraminiferans identified to genera. Sediment samples were

analyzed for potential prey. Chi square tests showed significant

differences between the relative abundances of organisms in

the buccal pouches and the sediment, and between the relative

abundances of live and dead organisms within the buccal

pouches. Selective indices show C. tolmiei to feed preferentially

on living foraminiferans, particularly Uvigerina sp. The feed-

ing behavior of this cadulid is similar to that of dentalioid

scaphopods.

INTRODUCTION

The class Scaphopoda is a very uniform group within

Mollusca, characterized by specialized habits and sim-

plified structures (Morton & Yonge, 1964). Scaphopods

are detritivores and micro-carnivores, living in the sand

with their shell apices above the substrate (Morton, 1967).

The shell is usually oriented with its concave side upward

(figure 1).

Palmer (1974) divided the Scaphopoda into the orders

Dentalioida and Siphonodentalioida, which can be dis-

tinguished on the basis of e.xternal features. The Den-

talioida have elongated conical shells and a conical foot.

The Siphonodentalioida have a vermiform loot with a

crenulated pedal disc, and are generally smaller than

dentalioids (Pelseneer, 1906; Palmer, 1974).

Scaphopods burrow and construct a feeding cavity

wherein the captacula probe the cavity walls (Gainey,

1973) and substrate, and detect and capture live fora-

miniferans and other prey (Morton, 1959; Gainey, 1973;

Bilyard, 1974). Dentalioid epipodial lobes may dislodge

and waft .sediment toward the oral aperture, where the

captacula probe it (Dinamani, 1963). When food is ab-

sent, scaphopods burrow to a new location (Gainey, 1973).

Dinamani (1963) observed Dentalium conspicuum

Melvill collecting and conveying particles along its cap-

tacula by ciliary action. These particles were whisked

onto the captaculum by the cilia on the bulbous tip and

transported along the filament to the mouth by ciliary

action. Morton (1959) suggested that D. entalis Linne

may use captacular alveoli as suction cups to capture

foraminiferans. Gainev (1973) observed D. cboreum

Conrad and D. pseudohexagonum Henderson probing

into the substrate with their feet to form feeding cavities

(figure L fc). The captacula then browsed along the

cavity walls and conveyed small particles to the mouth.

BiKard (1974) showed that D. cntalc stirnpsot}! Hen-

derson feeds selectively on living foraminiferans and or-

ganic material, and rejects dead foraminiferans and in-

organic material. There have been few studies on

siphonodentalioids. Davis (1968) described the captac-

ular behavior of Cadiihis qiiadridentatus Dall, but did

not observe feeding. Rokop (1977) reported a seasonal

reproductive cycle in C. californicus Pilsbry and Sharp.

CMduliis tolmiei is a common deepwater siphonoden-

talioid occurring in Barkley Sound, off the western coast

of Vancouver Island, British Columbia. The feeding be-

havior of this species is described and compared to that

of dentalioid scaphopods. The diet of Cadulus tolmiei

and the selection of particular prey items are reported.

MATERIALS AND METHODS

Specimens of Cadulus tolmiei were dredged from two

sites in Numukamis Ba\ on June 22, 1984. Site 1

(4S°53.70'N, 125°00.83'W to 48°54.01'N, 125°02.98'W,

in 139-199 m) yielded 26 specimens; site 2 (48°53.80'N,

125°03.12'W to 48°53.77'N, 125°03.84'W, in 157-183 m)

yielded 61 specimens (voucher specimens USNM 859073).

A thermometer was inserted into the samples immedi-

atel) upon collection to determine the bottom sediment

temperature. Temperatures at site 2 averaged 8.9 ± 0.4

°C. No sediment was obtained at site 1.

Twenty-four specimens from site 1 and 11 specimens

from site 2 were preserved in 37"^^ isopropyl alcohol

containing Rose Bengal. Shell lengths and oral aperture

widths were measured, and the specimens dissected. All

prev items were removed from the buccal pouches, live

(stained) and dead (unstained) prey items recorded, and

p. A. Poon, 1987

Page 89

— cb

^5f^'.;vY i'Vm^-PxC-^-

Figure 1. Cadulus folmici in sediment, showing orientation,

cb, captacular burrow, del, digestive diverticula; fc, feeding

cavity, g, gonad; m, mantle; pa, posterior appendix; s, shell.

prey maximum lengths measured. Foraminiferans were

identified to genus using the keys in Cushman (1959).

Sediment samples were immediately preserved in Rose

Bengal-isopropanol solution, sieved to 63 /jm and ex-

amined under a dissecting microscope. All stained po-

tential prey items were counted and collected.

A linear regression (Schefler, 1969) of C. tolmiei oral

aperture width vs. live prey item length was plotted and

the correlation coefficient calculated. Chi scjuare tests

(Siegel, 1956) were used to determine if there were sig-

nificant differences between the prey items in the buccal

pouches and in the sediment, and between the live and

dead prey items in the buccal pouches. Selective indices

(Bilyard, 1974), the ratios of percent organisms in the

buccal pouches to the percent organisms in the sediment,

were calculated for the major prey categories. Indices

greater than 1.0 indicate positive selectivity, values less

than 1.0 indicate negative selectivitv (BiKard, 1974).

Additional sediment was sieved through a 1 mm screen

to remove macro-invertebrates, and kept in plastic, mesh-

sided containers in circulating seawater (9.6 ± 0.2 °C).

These samples were further sieved through 275 nm. 180

ixm. and 63 nm screens to retrieve foraminiferans for use

as prey in feeding observations. Living Cadulus tolmiei

were attached to glass slides with rubber bands and placed

Figure 2. Observation tank constructed from 2 x 8 cm glass

slides. Scaphopod is attached to slide by rubber band.

about 1 mm above the substrate in a small glass tank

filled with sediment and seawater (figure 2). Tempera-

ture was maintained at 13.2 ± 0.8 °C. Specimens were

backlit to reveal internal activity through the translucent

shell. Foraminiferans were placed in the tanks and feed-

ing observed through a horizontally mounted dissecting

microscope.

RESULTS

Living and dead organisms taken from the buccal pouch-

es of Cadulus tolmiei were identified, counted, and are

listed in table 1. The site 2 sediment sample was com-

posed mostly of silty fecal pellets. Nematodes, annelids

and dead centric diatoms were common. The forami-

niferans Bu/iHiina sp., Vvigerina sp., Bolivina sp., Quin-

queloculina sp., and Rheophax sp. were present in the

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THE NAUTILUS, Vol. 101, No. 2

Table 1. Buccal pouch contents of 26 Cadulus lolmiei.

Table 3. Chi square test comparing live prey in sediment and

Table 2. Live potential prey in sediment

Pre\ items

Table 5. Selective index of percent prey in buccal pouches

and in sediment.

rey per ml

Foraminifera

Bulimina sp 0.6

Vvigerina sp. 0.1

Bolivina sp. 0.1

Nonionina sp. 0.1

Mollusca

Juvenile

Bivalves 0.1

Eggs

Thick shelled eggs 0,6

Thin shelled eggs 0 1

Total number of pre\ items: 90

Total volume of sediment examined: 58.6 ml

sediment sample. Rheophax sp. was common, as were

tests of dead Vvigerina sp. and Buliinina sp Tests of

Quinqueloculina sp.were less common. Rheophax sp. was

the only arenaceous foraminiferan found. Table 2 lists

the potential prey items in this sediment sample.

(-hi square tests indicated signilicaiit differences he-

Ivveeii the distribution ol prey items in the buccal pouch-

Prev items

Percent Selec-

Percent in buccal tive

in sediment pouches index

Bulimina sp.

Vvigerina sp.

Bolivina sp.

Thick slielled eggs

Thin shelled eggs

Juvenile bi\alves

es vs. the sediment (table 3) and between living and dead

prey items in the buccal pouches (table 4). Live Vvig-

erina sp. were strongly selected. Dead Bulimina sp.,

Bolivina sp., and thin shelled eggs were occasionalK

selected, but few live individuals were ingested. Live

thick-shelled eggs were selected over dead ones. Living

and dead juvenile bivalves were avoided (tables 5 and

6). The linear regression of prey size versus oral aperture

width is shown in figure 3, The slope is —25.3; the cor-

relation coefficient (—0.02) is insignificant.

The feeding behavior of 40 individuals was observed.

,\fter burrowing, each animal slowly extended and re-

tracted its foot with the pedal disc in\aginated. This

movement created a small feeding cavity (figure 1, fc).

p. A. Poon, 1987

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