JANUARY 30, 1976

THE

NAUTILUS

Vol. 90

No. 1

A quarterly

devoted to

malacology and

the interests of

conchologists

Founded 1889 by Henry A. Pilsbry. Continued by H. Burrington Baker.

Editor-in-Chief: R. Tucker Abbott

EDITORIAL COMMITTEE

CONSULTING EDITORS

Dr. Arthur H. Clarke, Jr.

Department of Mollusks

National Museum of Canada

Ottawa, Ontario, Canada K 1 A-OM8

Dr. WUliam J. Clench

Curator Emeritus

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. William K. Emerson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 1 0024

Mr. Morris K. Jacobson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 1 0024

Dr. Aurele La Rocque

Department of Geology

The Ohio State University

Columbus, Ohio 43210

Dr. James H. McLean

Los Angeles County Museum of Natural History

900 Exposition Boulevard

Los Angeles, California 90007

Dr. Arthur S. Merrill

Biological Laboratory

National Marine Fisheries Service

Oxford, Maryland 21654

Dr. Donald R. Moore

Division of Marine Geology

School of Marine and Atmospheric Science

10 Rickenbacker Causeway

Miami, Florida 33149

Dr. Joseph Rosewater

Division of MoUusks

U. S. National Museum

Washington, D.C. 20560

Dr. G. Alan Solem

Department of Invertebrates

Field Museum of Natural History

Chicago, Illinois 60605

Dr. David H. Stansbery

Museum of Zoology

The Ohio State University

Columbus, Ohio 43210

Dr. Ruth D. Turner

Department of Mollusks

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. Gilbert L. Voss

Division of Biology

School of Marine and Atmospheric Science

1 0 Rickenbacker Causeway

Miami, Florida 33149

Dr. Charles B. Wurtz

3220 Penn Street

Philadelphia, Pennsylvania 19129

KDITOR-IN-CHIEF

Dr. R. Tucker Abbott

Delaware Museum of Natural History

Box 3937, Greenville, Delaware 19807

Mrs. Horace B. Baker

Business and Subscription Manager

1 1 Chelten Road

Havertown, Pennsylvania 1 9083

OFFICE OF PUBLICATION

Delaware Museum of Natural History

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Box 3937, Greenville, Delaware 19807

Second Class Postage paid at Wilmington, Delaware

Subscription Price: $7.00 (see inside back cover)

THE

NAUTILUS

Volume 90, number 1 — January 30, 1976

CONTENTS

Publications Received; Editorial ii

Carl J. Berg, Jr.

Ontogeny of Predatory Behavior in Marine Snails (Prosobranchia: Naticidae) 1

Alex Tompa

Fossil Eggs of the Land Snail Genus Vallonid (Pulmonata: Valloniidae) 5

Thomas M. Duch

Asj^ects of the Feeding Habits of Viripnrvs (ironiinnun 7

Fred G. Thompson

The Occurrence in Florida of the West Indian Land Snail Biilimuhi>i fiuadalupensis 10

Robert A. Wharton

Variation in the New England Pyramidellid Gastropod, Turbomlla nivea (Stimpson) 11

John W. Clark, Jr.

Alvar Nunez and the Snail Rabdotuf^ in Texas 13

Alan Solem

Sjjecies Criteria in Anguispira (Anynisph-d) (Pulmonata; Discidae) 15

Henk K. Mien is

Range Extension of Coralliophila marrati Knudsen (Gastropoda: Magilidae) 23

R. Tucker Abbott

Cittariuni pica (Ti-ochidae) in Florida 24

Alan Solem

Comments on Eastern North American Polygyridae 25

G. L. Mackie

Trematode Parasitism in the Sphaeriididae Clams, and the Effects in Three Ottawa River

species 36

Fred G. Thompson

The Genus Epirobia in Chiapas, Mexico 41

Antonio J. Ferreira

A New Species of Callistochiton in the Caribbean 46

Artie L. Metcalf and Richard W. Fullington

A New Fossil Ashmunella (Pulmonata: Polygyridae) from the Guadalupe Mountains Na-

tional Park, Texas 49

Richard G. Woodbridge, HI

Tentacle-branching in the Periwinkle, Littofimt liftdiva 52

Arthur S. Merrill and Robert L. Edwards (A corrected republication]

Observations on Mollusks from a Navigational Buoy with Special Emphasis on the Sea

Scallop, Placopecten magellanicus 54

STATEMENT OF OWNERSHIP, MANAGEMENT AND CIR-

CULATION (Required by) Act of October 23, 1962: Section

4396. Title 39. United Stotes Cocte, end postal regulation

132-622.

1. Title of publication: THE NAUTILUS.

2. Date of filing, September 25, 1975

3. Frequency of Issue: Quarterly (4 per year).

4. location of known office of publication: Delaware

Museum of Natural History, Kennett Pike, Box 3937,

Greenville, De 19807.

5. Location of the Headquarters of General Business Of-

fices of the Publishers: Delaware Museum of Natural

History, Kennett Pike, Box 3937, Greenville, De. 19807.

6. Names and addresses of publisher, editor, and

manoging editor: Publisher, Mrs. Horace Burrington

Baker, 11 Chelten Rd., Havertown, Pa. 19083. Editor, R.

Tucker Abbott, Delaware Museum of Natural History,

Box 3937, Greenville, De. 19807. Managing editor,

none.

7. Owner: Mrs. Horace Burrington Baker, 1 1 Chelten Rd.,

Havertown, Pa. 19803.

8. Known bondholders, mortgages, and other security

holders owning or holding 1 percent or more of total

amount of bonds, mortgages or other securities: none.

9. Extent and Nature of Circulation:

Average Single

12 Mos Issue

A. Total No. Copies Printed (Net Press 1,000 1,000

B. Poid Circulation

1 Soles through dealers and cor-

ners, street vendors and counter

sales none none

2. Moil subscriptions 631 634

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D. Free Distribution (including samples)

by mail corner or other means 14 14

E. Total Distribution (Sum of C & D) 645 648

F Office use, left-over, unaccounted

and back start subscription copies 355 352

G. Total (Sum of E & F) — should equal

net press run shown in A. 1,000 1,000

I certify that the statements mode by me above ore

correct and complete,

(signed) R. Tucker Abbott, Editor

EDITORIAL

Rapid publication of research papers is now

possible, usually within two or three months of

submission of the manuscript, providing the

author pays page charges ($30.00 per page). This

priority does not in any way delay the papei-s

of other authors, since articles with paid page

charges merely increase the normal size of an

issue.

AMU 1976 ANNUAL

MEETING IN COLUMBUS

The annual meeting of the American

Malacological Union will be held Monday,

August 2 (registration) through Friday (field

trip) the 6th on the campus of the Ohio State

University, Columbus, Ohio. Inexpensive but ex-

cellent lodgings. More details in the April issue.

PUBLICATIONS RECEIVED

Humm, Harold J. and Charles E. Lane, editors.

1974. Bioactive Compounds from the Sea.

Marcel Dekker, Inc., N. Y. xiii + 251 pp.

$18.75. Among the 13 chapters resulting from

a 1971 symposium on this subject, some re-

late to toxins carried by marine mollusks,

especially those of dinoflagellates.

Johnson, Richard I. 1975. Simpson's Unionid

Types and Miscellaneous Unionid Types in

the National Museum. Special Occasional

Publ. no. 4, 56 pp., 3 pis. $4.00. Also includes

list of types of B. H. and S. H. Wright.

Olazarri, Jose. Nov. 1975. Hiatoria de la Mala-

cologia en el Uruguay. Foreword b.\' J. .1.

Parodiz. 121 pp., privately printed (115

copies). Montevideo, Uruguay.

Kaicher, Sally Diana. Sept. 1975. Cord Catalogue

of World-wide Shells. Pack 8, Naticidae, part

1. (cards 692-797). Write: 5633-B, 18th Way

South, St. Petersburg. Fla. ;33712.

Walne, P. R. 1974. Culture of Bivalve Molluscs

—.")<• Veal's' Experience at Conwy. 173 pp.. :38

figs., paperback, about $13.75. Fishing News

(Books) Ltd., 23 Rosemount Ave., West By-

fleet, Surrey, England. Details of the mari-

culture of Ostrea edulis. Mytilus edulis. Vene-

rupis decussata. and Mcrcenaria merccnaria

at the government Fisheries Rxperiment Sta-

tion, Conwy [Conway, Wales].

Kay, E. Alison and William J. Clench. 1975.

A Biobibliography of William Harper Peiise,

Malacologist of Polynesia. Nemouria. no. 16,

.")() pp. Gives Pease's life and lists about 660

of his new names, with references. $2.00 from

tlif Delaware Museum of Natural Histoiy,

P.O. li)x 3937. (Ireenville, Delaware 19807.

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 1

ONTOGENY OF PREDATORY BEHAVIOR IN MARINE SNAILS

(PROSOBRANCHIA: NATICIDAE)

Carl J. Berg, Jr.

Department of Biology

City College of City University of New York

New York, N. Y. 10031

ABSTRACT

Naticid gastropods (Natica gualtieriana) imre reared throitgh metamorphosis

and presented urith gastropod prey. The first prey were bored by a single well-

formed hole in a stereotyped position. As the animals matured and gained ex-

perience at boring there was no change in the circular distribution of the

boreholes in each whorl but whorl preference changed and the animals became

seemingly less proficient borers.

INTRODUCTION

Marine gastropods of the family Naticidae

are noteworthy because of their predatoi^ habit

of capturing bivalves or snails, boring a hole

through the hard calcareous shell, and con-

suming the soft parts within. There have been

numerous reviews of the controversy concerning

the mechanisms involved in boring (Ziegelmeier,

1954; Carriker, 1961; Fretter and Graham, 1962;

Hyman, 1967; Bernard, 1967) and the position

of the borehole (Ansell, 1960; Reyment, 1966).

While it has been suggested that ex-

periential factors play some role in prey selec-

tion of gastropods (Fischer-Piette, 1935;

Carriker, 1957; Wood, 1968; Morgan, 1972) there

are no studies of the ontogenetic development

of predatory behavior. Such studies are of par-

ticular interest wath those species of naticids

whose development includes a planktonic veliger

stage, during which they use ciliated velar lobes

to filter-feed on phyto plankton. These snails

possess neither a radula nor a proboscis until

after metamorphosis. Veligers are therefore in-

capable of boring and have no experience as

predators. I have found the complete behavior

patterns involved in prey manipulation and

boring to be present upon first experience with

a prey. I have also described how the position

and the quality of the borehole change as the

predators mature.

METHODS

Fourteen veligers of Natica gualtieriana were

collected from the plankton in Kaneohe Bay,

Hawaii, and reared separately in small (55mm

X 15mm) plastic petri dishes containing 20ml

of sea water. The animals metamorphosed

within 24 hours and were provided with a new

dish containing water, sand, and one prey-snail

every second day. Morphologically similar Bit-

ti'um and Rissoella species were offered as prey.

At each change of dish, the shells of the

previous prey were removed and taped to index

cards in sequential order for each predator. As

the A^. gualtieriana grew, larger prey were

provided, up to a maximum of 20 prey per

predator. The position of the borehole was

examined with respect to the longitudinal axis

of the shell and to the plane of the aperture by

determining the whorl in which the hole was

bored, the distance from the tip of the siphonal

canal to the center of the hole, and its circular

distribution. The pooled data were analysed

using standard statistical tests and tests for cir-

cular distribution patterns (Snedecor and

Cochran, 1967; Batschelet, 1965).

The shells from each predator were coated

with gold and examined under a Cambridge

Stereoscan (S4) scanning electron microscope.

Qualitative changes in the shape of the hole

and the amount of radular scraping were noted

for each series of shells.

Young specimens of Natica gualtieriana

Recluz used in these observations are deposited

in the Delaware Museum of Natural History,

no. 103100.

2 THE NAUTILUS

January 30. 1976

Vol. 9(1 (1)

B

FIG. 1. Scanning electron photomicrograph of the firxt

hirchotc made by a newly metamorphosed Natica

gualtieriana. Bar represents 0.1 mm.

RESULTS

Upon first presentation of prey, all newly

metamorphosed A'', giioltieriana bored a single

well -formed hole (Figure 1). There was no

evidence of incomplete boreholes or misplaced

rasping. The first holes were distributed with

mean values of either 273.3° to the right of

the aperture in whorl 2 (Figure 2A) or 114° in

whorl 3 (Table 1). There was no overlap in

the range of distribution for each whorl. The

centers of the holes were located 1.31 mm (Mdso

value) from the tip of the siphonal canal, which

represents (i5"/o (Mdso value) of the distance be-

tween the tip of the siphonal canal and the top

5 10 15

Prey Number

FIG. 2. Distribution of boreholes in prey of N.

gualtieriana. A. Shell of prey, indicating sectors used to

de.tigiiate circular distribution of boreholes around the shell.

A)row indicates position of mean angle <f first borehole in

whorl no. 2. R Distribution of the total sample of boreholes

in whorls no. 2 and no. 3. Arrows indicate mean ixdues

(Whorl No. 2 at sector 6; whorl no. 3 at sector 2). Broad

lines represent 2 angular deviation units. C. Percentage of

holes in each whorl for successive prey. Holes midtmy be-

tween irhorls counted for both whorls.

of the fourth whorl (Figure 3A). Measurements

were not made with respect to total shell

length because the prey were often missing the

initial smallest whorls.

If the total sample of boreholes drilled by the

14 predators is analyzed, distinct patterns

become evident. The holes drilled into the first

20 prey by each of the A^. gualtieriana were not

uniformly distributed around the circumference

of the shell (p < .05). Holes drilled in whorl 2

were located at a mean of 217° to the right of

the aperture, but holes in whorl 3 were only

TABLE 1. Distribution of Natica srualtieriiuia hircholcs in gnstrnpud prey.

Wotson & Williiims

Vol. 90 (1)

.lanuarv :{(), 1976

THE NAUTILUS 3

Co O

g; 00

-Wtt

+-i

E

E

I

20

5 10 15

Prey Number

FIG. 3. Distrihidion of borehates (dmiy the lonyitiidimil

(tr/.s of prey of N. gualtieriana. A. Shell of prey, indicatiiuj

diitance from tip of siphonal canal to center of borehole fa)

and to the top of the fourth whorl (b). Numbers indicate

whorl number, starting from the tip of the siphomU canal.

R Change in distance of borehole from the tip of the

siphonal canal (b) urith successive barings. Dots indicate

median i>alue.^, vertical lines the range of values. Y = 1.011

+ aimX. r = 0.80. C. Change of ratio fa/b) uith .suc-

cessive borings. Dots indicate median vabies, vertical lines

the ninye of m)ue.% Y = 6'.5.63 + 0.29.5 X. ;• = 0.29.

60.8° to the right (Table 1 and Figure 2B).

Although the range of distribution for each

whorl did overlap slightly, the difference in

mean values was significant (p < .001).

There was no significant change in the cir-

cular distribution of boreholes in each whorl

with increased experience or boring. However, a

dramatic change in whorl preference occurred

between the fifth and sixth prey bored (Figure

2C). Five animals switched from boring into

whorl 2 to boring into whorl 3, but only one

animal made the opposite switch. From the sixth

prey on, there was a significantly increased

preference for boring into whorl 3, with p < .01

for the difference from even distribution in

both whorls for prey number 17, 18, 19, and 20

combined.

The increased percentage of holes bored in

the more distant third whorl and the large size

of prey may explain the increase in the distance

between the center of the borehole and the

tip of the siphonal canal (Figure 3B). However,

the ratio of the distance between the tip of the

siphonal canal and the center of the borehole

and the distance from the tip to the fourth

whorl varied only slightly with experience

(Figure 3C).

DISCUSSION

The quality of the borehole and the proficiency

of boring seemed to decrease with repeated

boring. The boreholes became less round in ap-

pearance, indicating that the holes were not

bored perpendicular to the plane of the shell

surface, the walls of the holes were rasped in a

more random fashion, and the holes were not

bored completely through the shell although the

prey was eaten. There was one case of two

holes being drilled in the same prey and cases

of boreholes left incomplete and new holes

formed. In general, it seemed that the predators

became less proficient at boring during early

post-metamorphic development. This may reflect

changes in the sensory systems being used in

determining the suitability of prey and the

position of boring. Such changes would adapt

the animals for preying upon a greater variety

of prey species as they get older.

The position of the borehole is determined by

the way the prey is manipulated and positioned

for boring (Boettger, 1930; Ziegelmeier, 1954).

The behavior appears stereotyped in naticids.

Tactile characteristics of the aperture and

chemicals emanating from it are probably used

as cues by the predators. When shells of

greatly varying shape were given to A^.

gualtieriana. they were bored directly above the

aperture, regardless of the length or width of

the new prey shell. This preferred position lies

over the mantle cavity of the prey snail in its

withdrawn condition. This drilling position

probably confers on the predator certain selec-

tive advantages which have led to its becoming

fixed during evolution. One might explain the

advantages of the preferred site by a com-

bination of factors: 1) By boring on the same

plane as the aperture, the naticid's foot covers

this opening, blocking escape by the prey. 2) By

boring approximately midway along the

longitudinal axis of the shell, the extensible

proboscis, which enters the shell through the

borehole, has a greater probability of reaching

both ends of the shell and removing all of the

meat. Therefore, it probably makes little dif-

ference which part of the prey's body is con-

4 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

FIG. 4. Ytmitij Natica Kualtieriana U mm. in length) fnim

Kaneiihe Bay. Hnwnii, rai.ied in the labdratmy frmn the

ivlujer xtmir. rinfl ii.trd in shell horin;/ nhserrntidns.

sumed first, as Pieron (1933) and Verlaine

(1936) contended.

Since the position of the borehole is the

result of a complex series of behavior patterns

involving prey capture, prey manipulation, and

the actual process of boring, the stereotyped

position of the borehole reflects a stereotypy of

behavior. The stereotyped boring behavior of

naticid gastropods is present upon metamorpho-

sis; no experience is necessary. There is an

increase in the variability of borehole position

and a decrease in the quality of the borehole

during early post-metamorphic development.

These observations contradict Verlaine's (1936)

earlier conclusions based upon boreholes in

shells found on the beach. He suggested that

the naticids learn, by successive drillings, the

position of the gonads under the shells of

bivalves and therefore become more restricted

in their place of boring. This idea has not been

substantiated by my work or that of Bernard

(1967).

The gastropod mollusc A^. gualtieriana and

the cephalopod molluscs Sejria officinaiis and

Octopus cyanea (Wells, 1962; Wells and Wells,

1970) are competent predators upon metamorpho-

sis and, in fact, their behavior becomes more

variable with increasing age. This appears

distinctly different from the fact that ex-

perience is necessary for most vertebrate

predators and for the analogous behavior of nut

opening by squirrels (Eibl-Eibesfeldt, 1951).

ACKNOWLEDGEMENTS

Hawaii Institute of Marine Biology Con-

tribution No. 4620. I am grateful to J. Taylor,

E. Guinther, R. Phillips, and M. Grofik for their

help and to the members of the City University

of New York and American Museum of

Natural Histon,' Animal Behavior-Biopsychology

Training Program for commenting on the

manu.'^'ript.

LITERATURE CITED

Ansell. A. D. 1960. Observations on predation of Venus

strialula (Da Costa) by Natica alden (Forbes). Proc.

Mai. SiK-. Lmvi. 34: 157-164. 1 pi.

Batsehelet, E. 1965. Statistical methuds for the analysis of

problems in animal nrientatiun and certain biological

rhythms. A. I. B. S. Monog., Wash., D.C. 57 pp.

Bernard, F. R. 1967. Studies on the biologj- of the naticid

clani drill Pulinice.i leu'iii (Gould) (Gastropoda Proso-

branchiata). Fish. fles. Bd. Canada Tech. Rept. 42: 1-41.

B(iett(jer. ('. R. 19,30. Die Lage der Bfihrstelle beim Angriff

der Raub.sc'hnecken aus der Familie Naticida. Zeit. Wm.

Z«„l. 136: 45.3-463.

Carriker, M. R. 1957. Preliminar>' study of behavior of

newly hatched oyster drills, Urusalpinx einerea (Say).

./ Eiisha Mitchell Sci. Six-. 73: 328-351.

Carriker. M. R. 1961. Comparative functional morphology

of boring mechanisms in gastropods. Amer. Ziuil. 1:

26.3-266.

Eibl-Eibesfeldt. I. 1951. Beobachtungen zur fortpflanzungs-

biologie und Jungendentwicklung des Eichornchens

[Scitini.i nilgarif: L.). Zeit. Tierij.'ijfc. 8: .370-4i-K).

Fischer-Piette, E. 1935. Historic d'une mouliSre. Observa-

tions sur une phase de desequilibre faunique. Bull. Biol.

Franc. Belg. 69: 153-177.

Fretter, V. and A. Graham. 1962. British Prosobranch Mol-

luscs; their functional anatomy and ecology. Ray Soc.,

Lond. 775 pp.

Hyman. L. H. 1967. Tlie Invertebrates: Mollusca I.. Vol. 6.

Mt>Graw-Hill, N. Y. 792 pp.

Morgan. P. R. 1972. The influence of prey availability on

the distribution and predatory behaviour of Xucella lapil-

lus (L.). ,/. Amm. Ecol. 41: 257-274.

Pieron. H. 1933 Notes ethologiques sur les Gasteropodes

percurs et leur comportment avec utilisation de methode

statistique. Arch. ZahiI. Exper. Gen. 75: 1-20.

RevTnent. R. A. 1966. Preliminary observations on gastro-

jxid predation in the Western Niger Delta. Paleogeog..

Piileorlimntoi. Meoecol. 2: 81-102.

Snedecor, G. W. and W. G. Cochran. 1967. Statistical Meth-

ods. Iowa State Univ. Press., Ames. .593 pp.

Verlaine. L. 19.36. L'instinct et rintelligenoe ches les Mol-

lusques. Les Gasteropodes perceurs de coquilles. Mem.

Mus. Hist. Nat. Belg. 2: ,387-3<M.

Wells, M. .J. 1962. Early learning in Sepia. Zool. S(X. Lond.

Sipnp. 8: 149-169.

Wells, M. .1. and J. Wells. 1970. Observations on the feed-

ing, growth rate and habits of newly settled Octopus

cyanea. ./. Zool. Lond. 161: 6.5-74.

WiKxl. L. 196J<. Physiological and ecological aspects of prey

selection by the marine ga.stropod I'ro.ialpinx einerea

(Prosobranch ia: Muricidae). Malacologia 6: 267-320.

Ziegelmeier, E. 1954. Beobachtungen iiber den Nahrungser-

werb bei der Naticide Lunatia nitida Donovan (Gas-

tropoda Prosobranchia). Helgol. Wiss. Meeresuntersiich. 5:

1-.33.

Vol. 90 (1)

January 30, 197()

THE NAUTILUS 5

FOSSIL EGGS OF THE LAND SNAIL GENUS VALLONIA

(PULMONATA:VALLONIIDAE)

Alex Tompa

Department of Zcwlogy

Duke University

Durham, North Carolina 27706

ABSTRACT

Pleistocene fossil eggs of the land pidmonate genus Vallonia have been iden-

tified on the basis of idtrastructure, mineralogy and size. The eggs are remark-

ably well preserved and show a great deal of swrface detail with respect to their

calcite crystals. Similar comparisons of the ultrastructure of extant snail eggs

unth fossils should allow the identification of many more fossil species.

INTRODUCTION

During the course of my studies on the

mineralogy and ultrastructure of calcareous

land snail eggs. Dr. Claude Hibbard of the

Division of Paleontology, Museum of Zoology at

the University of Michigan, kindly provided me

with some fossil eggs that he had collected.

These eggs had been identified by F. C. Baker

as probably belonging to land snails (un-

published). However, their mineralogy and

ultrastructure had not been investigated. Since

the fossil shell fauna of this locality (Miller,

1968) includes many extant species and genera

whose eggs were recently investigated (Tompa,

1974a), an attempt was made to identify them.

MATERIALS AND METHODS

The eggs came from: 1) the Cudahy Fauna,

Meade County, Kansas, collected just below the

Pearlette ash (restricted), type 0, 600,000 BP

years, Loc. 10 (KU) S'/2NWV4 Sec. 2, T 31S., R.

28 W, Meade County, 2) Meade County, Loc.

UM-Kl-51-Sangamon NW 2 SW'4. Sec. 33, T

34S., R. 29W., and 3) McPherson County, Kan-

sas, Loc. #29, SW'/4 T18S., R4W, = Loc. UM-

Kl-62, Sandahl Local Fauna, Illinoian. The eggs

were untreated or briefly rinsed in distilled

water, then coated with gold and examined

with a JEOL JSM-U3 model scanning electron

microscope. Several eggs were crushed into a

fine powder, packed into Glaskapillaren of 0.5

mm diameter, and examined with x-ray dif-

fraction using CuKa radiation with a Ni filter.

at 35 kV, 15 mA, for 4 hours, with an 11.5 cm

camera.

RESULTS

X-ray diffraction analysis of the recent eggs

of Vallonia ptdchella (Miiller) and V. costata

(Miiller) shows that they are made of calcite;

the fossil eggs examined are also made of

calcite. Table 1 shows the results of

measurements taken of fossil eggs compared

with that of recent eggs of V. pidchella.

Figure 1 is a low magnification of a fossil

egg, showing that it is extremely well preserved,

intact. Figure 2 is a higher magnification of

another fossil egg, while figures 3 and 4 are

of the egg of extant V. pidchella. It should be

noted that the ultrastructural study of the egg

of V. pidchella and V. costata shows no dif-

ference; in fact, it seems that they are not

distinguishable on any basis. A comparison of

figure 2 with figure 3 shows that the two eggs

are identical on the basis of crystal size, shape

and pattern of distribution.

6 THE NAUTILUS

January 30, 1976

Vol. 90(1)

DISCUSSION

Miller (1968) found 3 species of the genus

Vallonia, V. cydophorella Sterki, V. graciliosa

Reinhart, and V. pulchella in the Cudahy

fauna, Meade County, Kansas. Tompa (1974a;

1975) found that the genus Vallonia has eggs

which are distinguishable from all other land

snail eggs examined on the basis of egg size

and ultrastructure, but the two species

examined, V. pitkhella and V. costata were in-

distinguishable from each other. On the basis of

the information presented here, it is concluded

that this fossil egg definitely belongs to the

genus Vallonia, and possibly to V. pulchella.

Pilsbry (1948) states that this genus, con-

sisting of about 25 species, is found in North

America above Mexico, Europe, North and Cen-

tral Asia and Japan. As fossils, vallonias are

known from the Paleocene, Eocene, Miocene and

Pliocene of Europe and Pleistocene of Europe

and America. It is an old group which ap-

parently evolved in Mesozoic time and has

changed very little since the Eocene.

I: . - ^

FK;. 1. SEM iifafnssnl egg. showing remarkable preservatinn itf tstrm-tior. XlOO FIG. 2. View of the surface ofatKithrrfnssit

egg. uiitrmtcd. Nate cri/stnl shape and distribution. X 1260 FIG. 3. Surface «>!/• nf the egg 0/ Vallonia pulchella. X1260. Note

.'<iinil<iritji of shape, size and distribution of crystals n-ith those <f figure 2. FIG. 4. Cross section »/ V. pulchella egg. shomng

that the large crystals are only on the surface layer. X3150

Vol. W (1)

January 30, 1976

THE NAUTILUS 7

The fact that such delicate and fragile objects

as calcified snail eggs should be preserved in-

tact is amazing. Hibbard (1949) describes the

method for their collection. It should be noted

that these snails, V. pvlchella and V. costata

generally deposit a single egg every 24 hours

(Whitney, 1938; Tompa, unpublished). Whitney

(op. cit.) also examined the effect of en-

vironmental changes on their rate of reproduc-

tion.

Fossil eggs much larger than these have also

been reported. Cox (1960) mentioned that large

oval bodies up to 30 mm in length, believed to

be fossil eggs of Filholia elliptica (J. Sowerby)

are found in the Oligocene of England, and that

similar bodies, probably eggs of Limicolaria. oc-

cur in the Miocene deposits of Koru, Uganda.

Hubricht (1952. 1964, 1965) reported eggs up to

3.6 mm in diameter and attributed the several

types found to the genera Discus and

Anguispira and/or Haplotrema. Since then,

Tompa (1974a, 1975) has documented over 35

genera in 17 families of Stylommatophora as

having calcareous eggs. Actually, land snail eggs

can be divided into three categories on the

basis of the degree of calcification of the egg

(Tompa, 1974b): 1) uncalcified, 2) partly

calcified, with discrete crystals dispersed

throughout the jelly, and 3) heavily calcified, or

"shelled," made of fused crystals. Many more

fossil eggs of this third group should be found

after a more careful examination of collections

(1 have seen small fossil snail eggs in collections

of fossil ostracods). A check-list of genera known

to form heavily calcified eggs has been made

(Tompa, 1974a) and should be useful in locating

additional fossil eggs. Moreover, many of these

eggs have already been examined with the scan-

ning electron microscope (op. cit; Tompa, 1975)

which should aid greatly in the identification of

fossils.

LITERATURE CITED

Cox, L. 1960. General characteristics of gastropoda, in

Treatise on Invertebrate Paleontology, C. Moore, ed. Univ.

Kansas Press.

Hibbard, C. 1949. Techniques of collecting microvertebrate

fossils. Gmtrih. Mux. Paleont. Univ. Mich. 8: 7-19.

Hubricht, L. 1952. The fossil snail eggs of the loess. Nau-

tUu.1 66: 33-34.

Hubricht. L. 1964. Some Pleistocene land snail records from

Missouri and Illinois. Sterhiana 13: 7-17.

Hubricht. L. 1965. Pleistocene land snails from Muddy

Creek, Mississippi. Sterlcimia 17: 6.

Miller. B. 1968. Planorbula campestris from the Cudahy

River (Kansas) of Meade County, Kansas, with notes on

the status of subgeneric categories of Planorbula. Mala-

cohigia 6: 253-65.

Pilsbry, H. 1948. Land moUusca of North America. Acad.

Natur. Sci. Phila, Monagr. 3.

Tompa, A. 1974a. The structure and functional significance

of the egg shell of Anguispira alternata (Say) with a sur-

vey of the occurrence and mineralogy of calcified land

snail ^gs. Ph.D. Thesis, The University of Michigan,

Department of Zoology.

Tompa, A. 1974b. The structure of calcareous snail ^gs.

Malac. Rev. 7: 49-50.

Tompa, A. 1975. A comparative study of gastropod egg shell

structure and mineralogy (in preparation).

Whitney, M. 1938. Some observations on the reproductive

cycle of a common land snail. Valhmia pulchella: influ-

ence of environmental factors. Pmc. Ind. Acad. Sci. 47:

299-307.

ASPECTS OF THE FEEDING HABITS OF VIVIPARUS GEORGIANUS

Thomas M. Duch

Bennett College, Millbrook, New York 12545

ABSTRACT

Study has been made on the feeding habits of Viviparus georgianus (Lea)

which were collected from a lentic zone of the Sawkill Tributary of the Hud-

son River. Viviparus feed on diatoms hut cannot break down all diatoms. The

results imply some orientation to diatom clusters, possibly related to a silt-mud

substratum. Aggregation behavior (f Viviparus is described.

8 THE NAUTILUS

January 30, 197fi

Vol. 90

Viviparus georgianus (Lea, 1884) is a fresh-

water prosobranch found generally in eutrophic

lakes, ponds, and slow-moving streams. The

specimens in this study were collected in the

Fall from a lentic zone of the Sawkill

Tributary of the Hudson River at Annandale-

on-Hudson. New York. Vegetative decay was

prevalent in the area, as well as an abundant

brown and green scum covering the surface of a

Slit-mud substratum which, according to Fritch

(1965), represents the diatoms in cluster. It was

on this scum that the animals apeared to graze.

The habitat of this study differs slightly from

that described by Cook (1949). In Cook's study,

Viviparus was confined to areas dominated by

rocks and only a small portion of mud while

Viviparus in this study was generally confined

to areas dominated by thick silt bottom and

few rocks.

This report describes aspects of the feeding

habits of Viviparus georgianus. After general

observations in the field and laboratory during

a period of two years investigations were

limited to: (1) an examination of gut contents;

(2) an examination of a possible substrate

preference; and (3) an investigation of a

po&sible relationship between feeding behavior

and substrate composition.

MATERIALS AND METHODS

The following methods and materials were

utilized for each of the behavioral in-

vestigations; (1) all experimental animals were

acclimated for at least one day before use in an

experiment; (2) the temperature was maintained

at between 20° and 25° C; (3) sterile, filtered

water from the Sawkill was used in all ex-

periments; (4) all apparatus were horizontally

leveled to limit the possible influence of a

geotaxic response; (5) all apparatus were

shielded with black paper to limit the influence

of reflected light; (6) and all experiments were

done separately with and without aeration in

both the Fall and Spring.

Fifty animals were placed in a mild solution

of magnesium sulfate which facilitated dissec-

tion and removal of the gut. After removal of

the gut its contents were flushed with water

and collected for examination. TTie gut effluent

was preserved and examined by the method of

Williams (1964).

The sizeable aggr^ations of Viviparus in

areas characterized by silt-mud and the

decreased concentrations of Vivipanis in other

areas of the Sawkill suggested a pxjssible sub-

strate association. This was investigated by op-

tically dividing a twenty gallon aquarium into

two sections. One section of the aquarium con-

tained sterile washed rock and gravel from the

natural habitat. The other section contained

sterile washed silt-mud from the same general

habitat. Twenty adult animals which had been

starved for ten days were then randomly placed

into the aquarium. The animals were then

allowed to acclimate for one day. The number

of animals in each section were then counted

each hour for a period of seven days. No data

was collected between 12:00 pm. and 7:00 ajn.

In addition, a second group of 20 immature

animals measuring 3-5 mm in diameter were

also used in the experiment.

Observations in the field and in the

laboratory also suggest that Vivipariu'i may

"seek out" clusters of diatoms associated with

the silt-mud substratum. To confimi this sup-

position, the following experiment was per-

formed. A mixed culture of diatoms consisting

primarily of the order Pennales was placed in

random areas on a substratum consisting of

only washed sterile silt. Twenty adult animals

which had been previously starved for a period

of one week were then added to the aquarium.

After an acclimation period of six hours ob-

servations were made of the animal's behavior.

During this time feces were removed to insure

that the animals would not feed on them. In

addition, the distance from diatom clusters was

measured from each animal. Distance

measurements were made at half hour intervals

for a period of twelve hours. At the ter-

mination of the experiment gut analyses were

done on each animal. Two modifications of the

preceeding experiment were done as follows: (1)

washed sterile gravel was substituted for the

silt and (2) the diatom clusters were placed

directly on the slate bottom of an aquaria.

RESULTS AND DISCUSSION

Observations in the field indicate that

Vol. 0(1

January 30, 1976

THE NAUTILUS 9

Vivipmiis in this study tend to aggregate in

silt-mud areas which are dominated by attached

filamentous algae and large clusters of diatoms.

Additional observations lead this observer to

believe that Vivipams may tend to avoid, or

cannot tolerate, conditions where blue-green

algae predominate.

Gut analyses of the animals from the field

showed that Viviparus do ingest and at least

partially break down diatoms and other algae.

Of the diatoms ingested, Merdion, Fragellana

and especially large naviculoid cells were con-

spicuously fragmented, but no specific fragmen-

tation pattern was observed. Other diatoms such

as Gomphonema and Diatoma were not con-

spicuously fragmented. The fragmentation of

only specific groups of diatoms may be related

to the structural features of the diatom fustrule

and the structure of the radular apparatus.

This should be further investigated. Blue-green

algae were absent in a vast majority of the gut

samples, but sparsely present in some samples.

FVagments of filamentous green algae were

found in all samples. In addition, in all of the

above gut samples, a conspicuous amount of a

fine grit was found. The importance of fine

particles of grit in the gut of at least some

gastropods has been demonstrated by Colton

(1908). He noted that in the absence of grit,

food was able to pass through the gut un-

molested. This may also be the case with

Viviparus.

In the laboratory experiments 80% of the

animals congregated and grazed upon the

spread diatoms in the silt sections of the

aquaria. A less intense congregation behavior

was observed when diatoms were provided over

gravel or slate substrata. All animals in the silt

section went through a burrowing behavior af-

ter most of the diatoms were removed. This ob-

servation is not in direct agreement with Cook

(1949) who stated that Viviparus is not an ac-

tive burrower. This behavior culminated in each

animal burrowing to at least half the depth of

its shell. After burrowing, the animals did not

move for a minimum of a half hour. Eleven of

the burrowed animals did not show locomotion

for two days. Gut analyses of the animals

which grazed on diatoms in the silt-aquarium

showed diatom fragmentation which was con-

sistent with the samples from the field. No or

little diatom fragmentation was found in the

guts of animals which were in the exposed slate

aquarium. This would tend to demonstrate that

diatom breakdovm is at least in part related to

the presence of grit in the gut of Vivipams.

In the substrate preference experiments with

no algae present, all animals initially showed a

random behavior and moved about with their

snouts moving from side to side. Six hours after

the beginning of the experiment all of the adult

animals had either moved to the silt side of the

aquaria or remained in the silt-mud side of the

aquaria. Why adults of Viviparus will be

aggregated to sterile silt in the absence of

diatoms was not ascertained. The immature

animals did not show this behavior.

No immediate directed orientation movement

to diatom clusters was observed. Instead, the

animals moved randomly but continuously,

until they came within an average of 10 centi-

meters of a diatom cluster. Thereafter, their

rate of movement intensified in the general

direction of the diatom cluster. Kohn (1961)

pointed out that Viviparus will respond to

organic compounds, and some herbivorous gas-

tropod species are attracted to stimuli em-

anating from food. In addition, Hyman (1967)

also reiterated that chemoreception is well-

developed in prosobranchs. Therefore, it is

possible that the previously mentioned in-

tensified movement may be related to

chemoreception. That is to say, that the initial

feeding behavior is undirected and upon

reaching the immediate area of the diatom

cluster the animal's behavior becomes directed.

Possibly the diatom mass provides a threshold

concentration of some organic stimulus in its

immediate area. Even if this is correct, it can

only be one of the stimuli to which Viviparus

responds when searching for food. The

aggregation response to a predominately silt-

mud substratum with a grit make-up in the ab-

sence of organic matter also may be significant

in locating areas associated with food. This may

then suggest that a possible tactile response or

possibly tactile memory may be involved in

locating an area where focxl may be present.

Tactile memory is well known in marine lim-

pets and chitons although it has not been

reported with Viviparus.

It may be noteworthy to point out that the

10 THE NAUTILUS

January 30. 1976

Vol. 90 (1)

aggregation behavior described in this paper

does not seem to be confined to Viviparus. Bov-

bjerg (1965) has shown that Stagnicola reflexa

tends to aggregate on patches of Spirogifra, and

Calow (1970) has demonstrated that Lymnaea

pereger tends to select green filamentous algae.

In summary, this study tends to show the

following: (1) that Viviparus will feed on

diatoms but cannot breakdown all diatoms; (2)

there is at least some orientation to diatom

masses; and (3) that the orientation may in

some way be related to a silt-mud substratum.

LITERATURE CITED

Bovbjerg, R. V. 196.5. Feeding and dispersal in the snail

Stat/nkiila reflexa (Basommatophora: Lymnaeidae). A/a/o-

coliigia 2: 199-207.

Calow, P. 1970. Studies on the natural diet of Lymnaea

pereger oblusa (Kobelt) and its possible ecological impli-

cations. Proc. Malac. Soc. Lond. 39: 203-215.

Colton, H. S. 1908. Some effects of the environment on

the growth of Lymnaea columella Say. Proceedings of

the Academy of Natural Sciences. Philadelphia. 60:

410-448.

Gx)k, P. M. 1949. A ciliary feeding mechanism in Vivi-

parux (L.) Proceedings of the Malacological Society of

London 27: 265-271.

Fritsch, F. E. 1965. The Structure and Reproduction of the

Algae. Vol. 11. Cambridge University Press. 939 pp.

Hyman. Libbie. 1967. The Invertebrates. Vol. VI. Mollusca

I. McGraw Hill Book Co.. New York. 702 pp.

Kohn, .Man J. 1961. Chemoreception in gastropod molluscs.

American Zoologist. 1: 291-308.

Williams, Louis G. 1964. Possible relationship between

plankton -diatom species numbers and water -quality esti-

mates. Ecology 45(4): 809-823.

THE OCCURRENCE IN FLORIDA OF THE WEST INDIAN LAND SNAIL

BULIMULUS GUADALUPENSIS

Fred G. Thompson

Florida State Museum

University of Florida

Gainesville, Florida 32611

Bulimulus guadalupensis (Brugui^re, 1789) is

widespread in the West Indies where it is

found on most of the Lesser Antilles, all of the

Greater Antilles and many of their satellite

islands. No doubt, its distribution prior to

man's arrival was much more restricted. The

snail adapts to a wide variety of environmental

conditions at low elevations within its present

range. It occurs near human habitation and is

easily disseminated to new areas on live agricul-

tural plants. Thus, it is not surprising that it

has become introduced into southern Florida.

Recently Bulimulus guadalupensis was col-

lected in Florida at three localities by field in-

spectors of the Florida State Division of Plant

Industries: (1) Snead Island, Palmetto, Manatee

Co., October 1969; (2) Eustis, Volusia Co.,

August 1975; (3) 1500 block, W. 7 Avenue,

Hialeah, Dade Co.. July-August, 1975.

Specimens from each of these localities are de

posited in the Florida State Museum. The first

two records involve specimens found at nur-

series on ornamental plants recently imported

from Puerto Rico. Established colonies at these

two places have not been confirmed. The third

locality, in Hialeah, has an established

population where the snail is abundant in a

residential area in lawns and among or-

namental vegetation. The geographic extent of

this population has not been determined. Most

likely the species soon will be found throughout

the greater Miami area.

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 11

VARIATION IN THE NEW ENGLAND

PYRAMIDELLID GASTROPOD. TURBONILLA NIVEA (STIMPSON)

Robert A. Wharton

Star Route

Somerset, California 95684

ABSTRACT

Based on the study of a large population of a highly variable species of Tur-

bonilla, and examination of type s])ecimens of T. nivea and T. stricta, it is the

itHthor's opinion that Turbonilla (Turbonilla) stricta Verrill, 1873. is a synonym

of T. (T.) nivea (Stimpson. 1851). The syntype of T. nivea located at the

Academy of Natuml Sciences of Philadelphia is not a typical example of the

species, but is well within the variation observed in a population from. Con-

necticut.

INTRODUCTION

Recent studies on Northwestern Atlantic

species of the genus Turbonilla revealed that

the characters originally used to separate two

of the species, T. (Turbonilla) nivea (Stimpson,

1851) and T (Turbonilla) stricta Verrill, 1873,

are insufficient. As Robertson (1968) noted, the

systematics of the Pyramidellidae is based

solely on shell characteristics. For example,

Verrill (1873), in his original description of T

stricta, stated that it differed from T nivea in

the form of the aperture and lip, and in being

smaller though having the same number of

whorls. Bartsch (1909) separated the two on the

basis of the number of axial ribs on the last

whorl (eighteen on T stricta and twenty-two on

T. nivea), and by a slight difference in the

shape of the aperture. A large population of

Turbonilla from Connecticut exhibited a high

degree of variability in these and other charac-

ters, making the existence of two distinct

species questionable. An examination of types

on deposit at the Academy of Natural Sciences,

Philadelphia (T. nivea syntype, ANSP #20013;

T stricta probable syntype or paratype, ANSP

#78205), confirmed the suspicion that the two

species should be synonymized. The Academy's

single specimen of T nivea was obviously

collected dead, as the shell is quite worn and

even has a drill hole in it. From the variation

shown by the population from Connecticut, and

the poor condition of the T nivea syntype, it is

easy to see how two species were described.

Over six hundred specimens were collected

from a population located subtidally in eel

grass beds off Noank, Connecticut, during 1970

and 1971. Most of the snails burrowed beneath

the sediment throughout the year, and were

seldom seen on the surfece. This may have been

due to a lack of surface materials, since a nearby

population lived beneath dead scallop shells

which littered the surface. Spawning occurred

in late summer, and the young snails grew to a

length of about 2 mm before winter. No growth

was added during the winter, and the shells

became thickened and opaque. Some of the

adult snails also survived the winter. Growth

resumed the following May and June. Ap-

proximately 2 mm of translucent shell material

was added by August. Spawning adults

averaged nearly 4 mm and had 8 to 9 whorls.

Snails dredged offshore from a depth of 30m

were somewhat larger, with more whorls.

Lunatia triseriata (Say) appeared to be the

chief predator of T. nivea at Noank, although it

preferred the less common T verrilli Bartsch.

Sanders (1958) has suggested that at least one

species of Turbonilla is a deposit feeder rather

than an ectoparasite. Because of their

burrowang habits and the scarcity of suitable

pr^y, feeding by T nivea was not actually ob-

served at Noank. Thus the question remains

unresolved, and much more work on this aspect

is needed. There is a well-defined series of

ciliary currents present on the foot, mentum,

and tentacles. These serve to transport substrate

particles over and around the head while

12 THE NAUTILUS

January 30, 1976

Vol. 9() (1)

tOt

to-

la-

<

-z so

o

Q^ 40-

QO

30

to-

10-

12 14 It 18 10 22 24 Zfc 2»

RIBS PfR IVHORL

1

FIG. 1. (iniph ahiiiniiii tlii' iiiinibcr of rihx per ivhnrl in a

xdiiiplc iif i-lll siimls.

burrowing, and might also be used in feeding if

the animal is a selective deposit feeder.

VARIATION

About five hundred snails were examined,

and the number of ribs on the youngest whorl

was counted. Figure 1 shows the result. The

continuous curve shows that this character

should not be used to separate species of the

subgenus Turbonilla. Such variation was due to

differences in both the width of the whorls and

the width of the ribs themselves. Variation in

length and number of whorls per shell did not

affect the variation in number of ribs per

whorl. Shells of the same size also varied in the

number of whorls they possessed. Similarly,

shells with the same number of whorls varied

by as much as one millimeter. The shape of the

ribs was also somewhat variable — even from

whorl to whorl in some specimens. Most were

slender and slightly curved. However, many

specimens had ribs that were straight. The size

of the aperture was measured and found to be

quite variable in this population: from

narrowly elliptical to squarish — though most

commonly broadly oval. Figures 2-6 illustrate

some of the variation in this species. A

representative series, showing the highly

variable nature of this species, was deposited at

the Academy of Natural Sciences of

Philadelphia.

Shell characteristics alone are generally unac-

ceptable for a clear understanding of specific

differences between species of the subgenus Tur-

bonilla, especially since population studies have

not been undertaken to determine variability

within a species. And until more complete

studies have been done, precise definitions of

the species will be impossible. Lopes (1958) and

Bartsch (1909) have also studied variation in

the shell characteristics (especially spiral in-

cisions) of Turbonilla. However, they were

dealing with other subgenera; and the

4 5 6

FICiS. 2-(;. Fire sperimeiix nf Turbonilla nivea aillected

friiiii Ihc sdtiic Idciililji .ihdirinii mriatidii iritliiii the species.

Vol. ;)() (1)

January :^(), 1976

THE NAUTILUS 13

taxonomic problems resulting from such

variation were less severe because of the

presence of other useful shell characters.

Other possible characters useful for describing

species of Turbonilia are the operculum, which

is elaborately sculptured in some species; the

color of the hypobranchial gland (Robertson,

1968), yellow-green in T. nivea; feeding habits

or host preference; presence (or possible ab-

sence) and form of the stylet; and the presence

or absence of denticles. Such denticles, for

example, are present in T. (PyrgiscusJ verrilli

but absent in T. (T.) nivea. They are quite

similar to the penial denticles figured by Maas

(1964). It is also quite probable that further

studies will reveal that the differences between

at least some species of T. (Pyrgiscus) and T.

(Turbonilia) are generic rather than subgeneric.

The Pyramidellidae as a whole, and the

genus Turbonilia in particular, need a great

deal of study before even some of the basic

taxonomic problems can be cleared up. Other

species of Turbonilia (eg. T. verrilli and T

vinae) should be examined for similar

synonymies. Populations should be studied to

determine variability, and a combination of

other characters should be used in conjunction

with shell morphology to redefine species.

ACKNOWLEDGEMENTS

I wish to express my deepest appreciation to

Dr. Robert Robertson for his assistance on

many aspects of this study. I also wish to

thank Miss Lauren Green for illustrating the

snails; and the faculty and staff of the Univer-

sity of Connecticut Marine Research

Laboratory, Noank, who provided much

assistance during the project. This research was

supported in part by an NSF Graduate

Fellowship from the University of Connecticut.

LITERATURE CITED

Bartsch, P. 1909. Pyramidellidae of New England and the

Adjacent Region. Prof. Bost. Soc. Not. Hist. 34(4): 67-112.

Lopes, H. S. 1958. Sobre Turbonilia (Pi/rgiscus) dispar Pils-

bry, 1897 (Gastropoda, Pyramidellidae). Rev. Brasil. Biol.

18(1): 17-21.

Maas, D. 1964. Liber Cuticularbildungen am Penis von Py-

ramidelliden. Zool. Anz. 173(2): 137-148.

Robertson, R. 1968. Hosts, Spermatophores and the Sys-

tematics of Five East American Species of Odostomia.

s.l. (Pyramidellidae). [Abstract]. Am. Malacol. Urmn Ann.

Repts. "1967" BulL 34: 12-13.

Sanders H. L. 1958. Benthic Studies in Buzzards Bay. I.

Animal -Sediment Relationships. Limnol. Oceanogr. 3(3):

245-258.

Verrill, A. 1873. Rept. U.S. Comm. Fiah nnd Fisheries.

pt. 1: 659.

ALVAR NUNEZ AND THE SNAIL RABDOTUS IN TEXAS

John W. Clark, Jr.

Texas Historical Commission

P.O. Box 12276, Capitol Station

Austin, Texas 78711

In a recent article in TTie Nautilus, Hester

and Hill (1975 : 38) discussed the possible

ethnohistoric account of Alvar Nunez Cabeza de

Vaca referring to the eating of snails in the

Gulf Coastal Plain. In an earlier article, also in

TJie Nautihis (Clark 1973:24) I lamented the

lack of ethnohistoric accounts referring to this

practice among the Texas Indians. Unfor-

tunately, this situation must remain lamented.

Hester and Hill depend on two sources:

Bishop (1933:95) and Krieger (1956:53). The

Krieger article on the food habits of the Texas

coastal Indians unfortunately indicates no

sources other than Cabeza de Vaca and that

somewhat vaguely. The problem of the Bishop

book is that there appears to be considerable dif-

ferences between it and more standard transla-

tions. Unfortunately, neither of these sources

agrees with the Bandelier (1906) translation, the

Covey (1963) translation or the original Spanish

(Nunez 1906 ed.).

There are two passages of the Cabeza de

14 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

Vaca Relaci6n pertinent to the discussion:

1) "Algunas vezes matan algunos venados, y

a tiempos tomaii algun pescado; mas esto es

tan poco y su hambre tan grande que comen

aranas e huevos de hormigas y gasanos e lagar-

tijas e salamanquesas e culebras y biuoras que

matan los hombres que muerden, y comen

tierra y madera e todo lo que pueden auer, y

estiercol de venados y otras coasa que dexo de

contar, y creo aueriguadamente que si en

aquella tierra ouiesse piedras, las comerian

(Nunez 1906 : 70)."

2) "En todo el tiempo que comiamos las

tunas teniamos sed y para remedio desto

beuiamos el (;umo de kis tun;i.s y sacauamosio

en vr\ hoyo que en la tierra haziamos, y desque

estaua Ueno beuiamos del hasta que nos har-

tauamos (Nunez 1906 : 75)."

Covey (1963) translates these passages

following the Spanish closely:

1) "Occasionally, these Indians kill deer and

take fish; but the quantity is so small and

famine so prevalent that they eat spiders and

ant ^gs, worms, lizards, salamanders, snakes

and poisonous vipers; also earth and

wood — anything, including deer dung and other

matter I omit. I honestly believe that if there

were stones in that land they would eat them

(Covey 1963 : 79)."

2) "The thirst we had all the while we ate

the pears, we quenched with their juice. We

caught it in a hole we hollowed out in the

ground. When the hole was full, we drank until

slaked (Covey 1963 : 83)."

The Bandelier translation is similar to that

of Covey.

Obviously, the Spanish word for snail,

"caracol" does not appear in these passages nor

does the word appear in any of the Spanish

language passages dealing with the Mareames

Mariames).

Thus, by examining the original Spanish text

one can see that, although Alvar Nunez

provides much information on the subsistance

of the Mariames and the central Texas coastal

Indians, he does not mention snails. T. C. Hill's

experiment (Hester and Hill 1975 : 38) indicates

that the Indians could have eaten Rabdotus sp.

snails. Likewise, their presence in vast numbers

in certain archeological sites is suggestive. As I

suggested in my 1973 article (Clark 1973:24)

the presence of radulae of these snails in

human coprolites would be the best indication

as to whether these animals were eaten. Un-

fortunately, none have yet been found in

human coprolites from Texas sites or any other

North American archeological sites.

Dr. Vaughn Bryant of the Anthropological

Research Laboratories at Texas A&M Univer-

sity (May 1975: personal communication) has

specifically searched for snail radulae during

the processing of coprolites but has failed to

find any. This may be due in part to the

procedure of sampling the coprolites, the selec-

tion of coprolites for analysis or the possibiliiy

that the Indians did not eat snails. I believe

that at present it is a sampling problem in

that coprolites have not been analyzed which

were associated with snail shell deposits in dry

rockshelters.

In summary, the Bishop (1933) monograph ap-

parently is in error, possibly leading Krieger

(1956) into error. The original Spanish text

(Nufiez 1906) does not mention snails nor do

two of the major translations, thus, there is

still no ethnohistorical evidence from Cabeza de

Vaca and Br>'ant has yet to find hard empirical

evidence for the eating of snails. As of the

moment, all theories are inferential.

LITERATURE CITED

Bandelier, Fanny (Translator). 1904. The Journey of Alvar

Nunez Cabeza de Vaca and His Companions from Florida

to the Ricific 1528-1536. Allerton Book Co., New York.

Bishop, Morris. 1933. The Odyssey of Cabeza de Vaca. The

Century Co., New York and London.

Clark, John W.. Jr. 1973. The Problem of the Land Snail

Genus Rabdotus in Texas Archeological Sites. The Nau-

tUus 87(1): -24.

Covey. Cyclone (Translator). 196:3. .idventures in the Un-

known Interior of America. Collier Books, New York.

Hester, Thomas R.. and T. C. Hill, Jr. 197.5. Eating Land

Snails in Prehistoric Southern Texas: Ethnohistoric and

Experimental Data. The Nautihis 89(2): 37-38.

Krieger, Alex D. 1956. Food Habits of the Texas Coastal

Indians in the Early Sixteenth Centurj-. Bulletin of the

Terns Atrheological Society 27: ■17-.58.

Nufiez Cabeza de Vaca, Alvar. 1906. Relaci6n de los Nau-

fragios y Comentarios de Alvar NtiHez Cabeza de Vaca.

Adelantado y Gobernador del Rio de la Plata. Coleccion

de Libros y Documentos Referentes a la Historia de

America, Tome V. Libreria General de Victoriano Sua-

rez, Madrid.

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 15

SPECIES CRITERIA IN ANGUISPIRA (ANGUISPIRA)

(PULMONATA: DISCIDAE)

Alan Solem

Department of Zoology

Field Museum of Natural History

Chicago, Illinois 60605

ABSTRACT

The functioning surface of the penis in Anguispira (Anguispira) shows con-

sistent differences in pilaster pattern among A. alternata (Say, 1816), A. cum-

berlandiana (Lea. 18WI. and A. picta (Oapp, 1920), although the gross ap-

pearance of their genitalia is nearly identical. Investigation of the con-

chologicaliy divergent morphs lumped as A. alternata probably will result in

recognizing several species. The genital difference reported here corresponds

with major shell shape and scuiptwre differences. Radular structure in the

Disddae, as represented by Anguispira, is generalized and differs from the basic

patterns found in the (Jharopidae, Endodontidae, and Helicodiscidae.

INTRODUCTION

The ribbed and unicolored to flammulated

shells grouped as Anguispira and Discus have

been monographed by MacMillan (1940) and

Pilsbry (1948). Comparison of these papers

shows considerable disagreement as to species

limits and affinities, although the generic limits

are the same. MacMillan (1940) relied strictly

on the shell for taxonomic decisions and Pilsbry

(1948: 566) indicated that ". . . fundamental inac-

curacies are involved" in MacMillan's

phylogenies. Preliminary work by H. B. Baker

on the anatomy of various species of Discus

was included by Pilsbry (1948: 599-600) in the

form of a key, together with some anatomical

details on both Anguispira (A.) alternata (Say,

1816) and A. (Zonodiscus) kochi kochi (Pfeiffer,

1845) (Pilsbry, 1948: 568, fig. 304), and, ad-

ditionally. Discus (D.) patulus (Deshayes, 1830)

(Pilsbry, 1948: 599, fig. 327). Subsequently For-

cart (1957) commented on the subgeneric

divisions of Discus; Uminski (1962) revised the

Palearctic species of Discus and summarized the

widely scattered European literature; and

Uminski (1963) reported on the anatomy of

Discus marmorensis H. B. Baker, 1932.

Various discrepancies and contradictions in

these accounts will be discussed elsewhere

(Solem, in preparation). Here, it is sufficient to

point out that the species of Discus have

several longitudinal pilasters within the penis

(Pilsbry, 1948: 599, fig. 327a; Uminski, 1963: 84,

figs. 5-8) and in Anguispira there are only two

pilasters, one very large and the other small

(Pilsbry, 1948: 568, figs. 304C, 304F). There has

not been any detailed study of the anatomy in

different species of Anguispira previously, and

unpublished observations by Hubricht, Grimm

and myself had failed to identify species level

identification features from the external aspects

of ttie genitalia.

During a survey of rare and potentially en-

dangered land snail species of Eastern North

America for the Office of Endangered Species,

it was necessary to investigate the status of the

taxa grouped as Anguispira (A.) cum-

berlandiana (Lea, 1840). MacMillan (1940: 392-

394) and Pilsbry (1948: 586-589) recognized four

subsf)ecies, A. c. cumberlandiana (Lea, 1840)

from Northeastern Alabama and Tennessee; A.

c. alabama (Clapp, 1920) from Northeastern

Alabama; A. c. columba (Clapp, 1920) from

Marion Co., Tennessee; and A. c. picta (Clapp,

1920) from near Anderson, Franklin Co., Ten-

nessee. Clapp (1920) described Anguispira picta

as a full species, and Hubricht (unpublished)

agreed with this opinion on the basis of shell

features.

This paper reports on species level differences

in the terminal genitalia of Anguispira

16 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

(Anguispira) altemata, A. cumberlandiana. and

A. picta. and thus suggests features that can be

investigated to determine the status of the

many forms that have been lumped as A. (A.)

altemata by earlier authors and Pilsbn,- (1948),

but split into several species by Hubricht (1952,

1965. 1968, 1970, 1974) on the basis of field ob-

servations and shell features. Radular teeth of

the same three species are illustrated to show

the basic structures and inter-row support

mechanisms of the central and lateral teeth in

the Discidae.

The field work by Mr. Glenn Goodfriend was

supported by Office of Endangered Species Con-

tract 14-16-0008-764, which also provided for the

excellent anatomical illustrations by Elizabeth

A. Liebman. OES Contract 14-16-0008-965 sup-

ported the page and illustration charges for

publication. The scanning electron microscope

photographs were taken with a Cambridge S4-10

Stereoscan provided to the Field Museum of

Natural History by NSF Grant BMS72-02149.

The SEM prints were prepared by Fred Huys-

mans. The help of Sharon Bacoyanis and Eliza-

beth Liebman in manuscript preparation is

gratefully acknowledged as is the support and

help given this project by the Office of Endan-

gered Species staff, particularly Marc Imlay.

MATERIAL STUDIED

The data on the illustrated material are as

follows :

Atiyuitipira (A.) altemata (Say, 1816). North-

west side of Route 272, 0.4 miles southwest of

Route 270 junction, north side Rich Mountain,

Polk Co., Arkansas. Glenn Goodfriend! Sep-

tember 13, 1973. Field Museum of Natural

History 176186.

Anguispira (A.) cumberlandiana cum-

berlandiana (Lea, 1840). Near Martin Springs

Road, 8 miles south of Monteagle, Marion Co.,

Tennessee at 960 feet elevation. Glenn Good-

friend! September 4, 1974. FMNH 171433.

Anguis-pira (A.) picta (Clapp, 1920). Southwest

side of Buck Creek Cove, 4 miles south of Sher-

wood, Franklin Co., Tennessee at 750 feet

elevation. Glenn Goodfriend! September 6, 1974.

FMNH 171138.

Several additional sets of typical A. alierrmta

were dissected, but are not illustrated, since

they agreed with the structures seen in the

figured material. What appears to be seasonal

variation in the prostate-uterus and develop-

ment of the main pilaster was discovered.

Material collected at the same time of year was

selected for illustration, despite the geographic

incongruence of the A. altemata set.

FIG. 1. Genitalia nf Anguispira; a, Anguispira altemata

altemata (Say. 1816). FMNH ITKlSti. Nmih side of Rich

.Ml.. Polk- Co.. Arkatisas: b, Anguispira picta (Clapp. 1920).

FMNH ITlliS. Buck Creek Cow. south of ShcrwtHid.

Fniiiklin Co., Tennessee; c, Anguispira cumberlandiana

cumberlandiana (Lea. mO). FMNH 17U.iS. About S miles

south of Moulcayle. Marion Co., Tennessee. Scale lines equal

5 mm.

Vol. 9(1 (1)

January 30. 1976

THE NAUTILUS 17

FIG. 2. Penis internal structure and talon in Anguispira:

a, Anguispira altemata alternata (Say, 1816): b, d,

Anguispira picta (Gapp, 1920): c, Anguispira cum-

berlandiana cumberlandiana (Lea. 181,0). Sixde lines as

marked, d yreatly enlarged.

TERMINAL GENITALIA

The apical genitalia of A. altemata and A.

picta are not illustrated, since the ovotestis (G)

and hermaphroditic duct (GD) showed no dif-

ferences from the structures seen in A. cum-

berlandiana (fig. 1 c). All three species have the

tri-lobed talon (fig. 2 d, GT) first reported by

Pilsbry (1948: .568. fig. 304D). A. picta (fig, 1 b)

does have a slightly longer prostate (DG) and

uterus (UT). but this may be a facet of in-

dividual population variation. The very long

spermatheca (S) and slender, fingerlike albumen

gland (GG) also are typical of the Discidae. A.

alternata (fig. 1 a) does have a shorter free

oviduct (UV) than either .4. picta (fig. 1 b) or

A. cumberlandiana (fig. 1 c). There is a slight

variation in the length of the vagina (V), but

because of the angle at which the spermatheca

joins the free oviduct to form the vagina,

measuring the exact length of the latter is very

difficult.

In all Anguispira (Anguispira) examined so

18 thp: nautilus

January 30, 1976

Vol. 90 (1)

far, the vas deferens (VD) emerges abruptly

from the acini bundles of the prostate, narrows

slightly and lies free of the adjacent tubes in

its passage to the peni-oviducal angle, then

reflects apicad to enter the penis (P) through a

simple pore (fig. 2 c, DP). The vas deferens en-

trance is lateral to insertion of the penial

retractor muscle (PR), which, contrary to

previous literature statements, arises from the

diaphragm, not the columellar muscle. In all

cases the insertion of the penial retractor

muscle is on the apex of the penis. The

illustration of A. cumberkwdiumi (fig. 1 r)

suggests that the insertion is slightly lateral in-

stead, but this is an artifact of preservation.

The illustrated specimen was partly retracted

into the shell. As part of the retraction process,

the penis is shifted apicad relative to the origin

of the penial retractor muscle. At full shift the

apex of the penis is bent slightly to the left

and the retractor muscle extends diagonally an-

teriorly, rather than in its normal apical orien-

tation. When fixed in the preservative, this

slight distortion can be misinterpreted as part

of the basic structure unless it is compared

with the condition found in fully expanded

materials.

There is a definite difference in the shape of

the penis, which is caused by the quite

divergent internal pilaster structures (figs. 2 a-

(■). In .4. cunibcHiuKtiinid (fig. 1 c) the penis

tapers almost evenly from apex to atrial junc-

tion (Y). In .4. pirta (fig. 1 b) the penis has an

almost uniform diameter on its upper two-

thirds, then rapidly narrows toward the atrium

on its lower third. A. (dteniata (fig. 1 a) has a

more bulbous penis that narrows slightly

apically, but tapers toward the atrium on its

lower two-fifths. Typically these differences can

be detected, but flattening during dissection or

in the initial preservation process can distort

individual specimens and mislead the observer.

Only by slitting the penis from atrium (Y) to

penis pore (DP) and studying the major

pilasters, can the differences (fig. 2) be seen

clearly and the species differentiated without

question. In A. nUcniata (fig. 2 a) the major

pilaster (PP on left) expands to great size,

tapers very slightly at the apex, and sharply

near the atrium. The second pilaster (PP on

right) is a narrow, much lower, raised ridge

that varies at most slightly in height over its

entire length. In A. picta (fig. 2 h) the major

pilaster (PP) expands much less, even on its

lower third, then narrows greatly toward the

middle, and is a relatively narrow ridge in its

upper half. The second pilaster is lower, wider

on its lower half, then broadens into a semicir-

cular pilaster on its upper half. The second

pilaster itself is composed of less dense tissue.

In A. cumbeiiandiana (fig. 2 c) the main

pilaster is rather high and narrow, without

major size change from near the apex to near

the atrium. The second pilaster is greatly

reduced in height, becoming a wide, nearly flat

patch of fibrous tissue. Near the middle of the

penis in each species, a "pocket" is formed by a

flap of tissue running between the two

pilasters. This is vaguely similar to a structure

found in many Charopidae, but apparently formed

quite differently (Solem, unpublished). All

Aryuispira have vague longitudinal fold ridges

extending from the atrium into the penis base

(figs. 2 (i-c). One or two of these may extend up

alongside the major pilaster, but I have not

dissected enough individuals to determine if the

longer ridge shown for A. cumberlandiana (fig.

2 <■) is an individual variation or represents

another species difference. The different shapes

found in the two large pilasters are charac-

teristic within quite narrow limits and thus

represent species differences.

The above observations are based on studying

five individuals from each population, and on

sampling ten populations from the Middle West

and Eastern United States of A. alternata. The

differences in pilaster structure are constant

and I conclude that they are valid species dif-

ferences. Thus A. picta is distinct from A. cum-

berlandiana. as originally proposed by Clapp

(1920), and both are distinct from A. alternata,

Restudy of dissections that I had made many

years ago of .4. fetyusDni (Bland, 1861) ft-om

Cambridge, Maryland, (specimens courtesy of

Halpli Jackson). .4. niarnrili Walker, 1928 from

Alabama (specimens courtesy of Leslie

Hubricht), and new dissections of A. mordax

(Shuttleworth, 1852) from Well Spring, Camp-

bell Co., Tennessee (FMNH 1.37820, L.

Hubricht! June 5, 1964) show equally different

Vol. m

January 30, 1976

THE NAUTILUS 19

FIG. 3-8. Central and lateral radvlar teeth. Figs. 3-5, 8.

Anguispira pirta (Clapp. 1920). FMNH 1711.18. Fig. 3.

Newly funned central (upper center) and 1st lateral teeth.

llSaX. Fig. 4 Lateral teeth from mid sectimi of radula

shomng functioning of support ridge and anterior flare.

1,260X. Fig. 5. Central (tipper right) and lateral teeth

viewed from anterior angle, erected podtion. 650X. Fig. 8.

Late lateral tooth viewed from low outside angle to show

extent of free anterior margin. l.;il5X. Figs. 6-7.

Anguispira cumberlandiana cumberlandiana (Lea. ISUO). Fig.

6. Central (left) and l.ft lateral near posterior end of radula

showing dual support ridges on central, single support ridge

on lateral, marked anterior flare of lateral. 1,250X. Fig. 7.

Central and early lateral teeth viewed from a high

posterior angle. 6.50X.

20 THE NAUTILUS

January 30, 197fi

Vol. 90 (1)

FIGS. 9-14. Marginal radular teeth. Figs. 9-10. Anguispira

alternata alternata (Say. Ifilf!). Fig. 9. Outer marginals

frciiii high ixinteriar angle. l..iOOX. Fig. 10. Outer marginals

on a creased area to show shape and angle of elevation,

l..iOnX. Fig. 11. Anguispira cumberlandiana cum-

berlandiana (Lea. ISiO). FMNH 17W!.i. Midmarginal. teeth

from II liigh central angle. t;2.5X. Figs. 12-14. Anguispira

picta (Clapp. 1920J. FMNH 17I1M Fig. 12. Transition from

lateral to marginal teeth. IjmX. Fig. 13. Outermost

marginals shoiving splitting of side cusps. 1.250X. Fig. 14.

Oiitprmost marginals from a high nntrrinr angle. l.ll.^X.

Vol. % (I)

January 30. 1976

THE NAUTILUS 21

FIGS. 1.5-18. Radular teeth. Figs. 15-17. Anguispira alter-

nata alternata (Say. 1816). FMNH 176186. Fig. 15. Newly

formed early lateral teeth showing function of basal siipixiii

ridge. 1,050X. Fig. 16. Worn central and early lateral teeth

from anterior end of mdnla. lOOOX. Fig. 17. Lateral teeth.

pilaster patterns in these taxa. Revision of the

Anguispira alternata group is beyond the scope

of this study, but the existence of distinctive

pilaster patterns in some of its more strongly

characterized "races" indicates that several

species are represented, as Hubricht has

suggested previously on the basis of his collect-

ing experiences. An investigation of penis

pilaster structure in this complex can be ex-

pected to yield significant data, despite the lack

of obvious differences in the gross genitalia.

RADULAR STRUCTURE IN ANGUISPIRA

The radulae were prepared using the

techniques outlined in Solem (1972). Published

illustrations have been chosen to demonstrate

the functioning and structure of the inter-row

support system in the Discidae, to illustrate the

1.160X. Fig. 18. Anguispira picta (Oapp. 1920). FMNH

1711S8, Transition from lateral to marginal teeth shouing

shortening of basal plate and reduction of anterior flare.

I.IWX.

pattern of change from lateral to marginal

teeth, and to demonstrate the form of the

marginal teeth. Differences between the three

species are trivial, with A. cumberlandiana (fig.

7) having a smaller central tooth in relation to

the 1st laterals than either A. picta (fig. 3) or

A. alternata (fig. 16) and A. alternata (figs. 15-

17) having a more prominent ectocone on the

lateral teeth than either of the other species.

The rachidian or central tooth of the radula,

marked "r" in figs. 3-7 and 16, has very weak

to weak ectocones, a variably (fig. 7) indented

and sinuated anterior margin, no anterior flare,

and two prominent lateral buttresses on the

basal plate (figs. 3, 6, 7). The first lateral teeth

are immediately recognizable in that they lack

an endocone (fig. 7) and in having the basal

plate buttress only on the outer side of the

22 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

basal plate (fig. 6). In addition, there is a

distinct anterior support flare on the early

laterals that is lacking in the rachidian tooth

(fig. 5). When a tear in the basal membrane

partly separates two rows of teeth (figs. 5-7),

then the basal plate structures and anterior

flares can be observed quite easily. After the

first few lateral teeth, the basal flare becomes

accentuated and somewhat elongated (fig. 8),

with the anterior two-fifths of the tooth free

of the basal membrane. This is the generalized

"helicoid" pattern for inter- row support of the

laterals (see Solem, 1972; pi. 5, figs. 22-23). Figs.

3, 4, and 7 show the stress support system in

various phases of operation. For the rachidian

tooth, the anterior margin is pressed back

against the basal plate and fits right in be-

tween the latei'al buttresses. Fig. 7 shows two

stages in the process: at far left, the anterior

flare is tilted down, but not in contact with the

basal plate, while at far right the flare is in

contact. Fig. 16 shows the interlock system in

full operation even more clearly. The first

lateral teeth differ only in the stronger anterior

flare being pressed partly against the shaft of

the cusp and partly against the outside buttress

(lower left of fig. 4 and center of fig. 15).

This is a highly generalized buttress system

that is widely distributed in the Pulmonata and

yields no information as to the phylogeny of

the group.

Transition from lateral to marginal teeth oc-

curs fairly abruptly (figs. 17-18) and involves

changes in basal plate, anterior flare, cusp

length, and angle at which the cusp is pointed.

Fig. 17, top to bottom, shows the shortening of

the anterior flare, while the different angle in

fig. 18 demonstrates the further progression in

this loss and the then very rapid change in the

length of the posterior section of the basal

plate. The shift is completed vidth the teeth at

the bottom of fig. 18, where the anterior

margin is simply rounded, the cusp is at a

lower angle, the posterior section of the basil

plate is greatly shortened, and the lateral but-

tress on the basal plate is lost. The shift in

angle of the cusp continues to the point shown

in fig. 12, where the cusp is elevated a com-

paratively few degrees from horizontal. At this

point, a weak endocone may appear on some of

the marginals, although most (fig. 11) will have

only a small knob-like protrusion. Newly for-

med marginals (figs. 9, 10) in A. alternata show

no special features, but fig. 10, which was taken

at a curve in the radula, effectively demon-

strates the cusp angle. Outermost marginal

teeth (figs. 13, 14) show irregular splitting of

the ectocone with teeth in successive rows

showing different ectoconal splitting features. In

some individual outer marginal teeth there is a

weak endocone (upper right of fig. 14).

In maintaining a basically bicuspid condition,

the lateral and marginal teeth of the Discidae

differ from those of the Charopidae (Solem,

1974: 167) or Helicodiscidae (Solem, 1975: figs.

6-8) which are essentially tricuspid with often

extreme cusp splitting. The Endodontidae

(Solem, 1973: figs. 6-9, 13-14) also have bicuspid

lateral teeth with bicuspid to tricuspid

marginals, but the inter-row support system

(l(ir. cit.. figs. 6, 14) is very different. The an-

terior margin of the lateral teeth is rounded

and totally lacks an anterior flare, the cusps

are narrower and curved, and support comes by

pressing against the raised posterior tip of the

basal plate ridge. When viewed with optical

equipment, the endodontid and the discid

radulae would look essentially identical, but the

functioning patterns in the two groups are

very different.

SHELL FORM AND GROSS SCULPTURE

Differences in shell form and sculpture be-

tween the nominate taxa of the three species

have been covered quite adequately by Mac-

Millan (1940) and Pilsbry (1948). Aiiguispira

alternata (Say) has a rounded to angulated

periphery on the body whorl and weak to very

strong radial ribs that continue across the

periphery and into the umbilicus. A. cuw-

berlandiana (Lea) has a protruded, thread-like

peripheral keel wath prominent radial ribs that

mntinue across the keel. A. picta (Clapp) has

the radial ribs present on the upper spire, but

absent from the body whorl and with the

protruded peripheral keel smooth and without

any trace of radial ribbing.

Because races of .4. alternata and A. cum-

berlandiana vary greatly in the prominence of

their sculpture, considerable uncertainty con-

;m) (1)

January 30. 1976

THE NAUTILUS 23

tinues to exist concerning the limits to be

assigned sculptural variation within a species.

Thus the decisions by MacMillan (1940) and

Pilsbry (1948) to combine A. picta with .4. cuni-

berlandiana were based on the latitude of

sculptural variation in the morphs lumped as

A. alternata. The demonstration here of dif-

ferences in the penial pilaster patterns be-

tween .4. picta and ,4. cumbcrlamiiana suggests

that investigation of the named forms of A.

alternata that show widely divergent sculpture

may lead to a splitting of that taxon into sev-

eral discrete units.

LITERATURE CITED

Qapp. G. H. 1920. A new species of Pyramidula from Ala-

bama and notes on P. rnmherlandiana with new varie-

ties, ne Nautilii.« 34(1): 23-26, pi. 1.

Forcart. L. 1957. Zur Ta.xionomie und Nomenklatui' von

Gonyodiscus. Discus und Patula (Endodontidae). Arch.

Mali. 86(1/3): 29-32.

Hubricht. L. 19.52 The Land Snails of Pittsylvania Count>'.

Virginia, nie Nautittis 66(1): 10-13.

Hubricht. L. 1965. The Land Snails of Alabama. Sterkiana

17: 1-5.

Hubricht, L. 1968. The Land Snails of Kentucky'. Sterhmnn

32: 1-6.

Hubricht. L. 1970. TTie Land Snails of North Carolina.

Sterkiana 39: 11-1.5.

Hubricht. L. 1974. A Review of Some Land Snails of the

Eiistern United States. Miiliiciil<yical Reriew 7: 33-34.

MacMillan, G. K. 1940. A Monographic Study of the Snails

of the Genera Anguispira and IHsciui of North America,

EAclusive of Mexico. Ann. Carnegie Miis. 27(24): 371-426,

pis. 38-42.

Pilsbry, H. A. 1948. Land Mollusca of North America

(North of Mexiaj). Arad. Nal. Sci.. Philadelphia, Monog.

a 2(2): i-xlvii, .521-1113, figs. 282-.5«.5.'

Solem. A. 1972. Malacological Applications of Scanning Elec-

tron Microscopy. — II. Radular Structure and Functioning.

The Veliger 14(4): 327-336, pis. 1-6, 1 text fig.

Solem, A. 1973. A New (ienus and Two New Species of

Land Snails from the Lau Archipelago of Fiji (Mollusca:

Pulmonata: Endodontidae). The Veliger 16(1): 20-30, 1

table. 21 figs.

Solem, A. 1974. The Shell Makers: Intnidneimj Mdlluxkit.

John Wiley & Sons. 289 pp.

Solem, A. 1975. Polygyiiscvs virginianus (Burch, 1947) a

Helicodiscid Land Snail (Pulmonata: Helicodiscidae).

77k- NautUus 89(3): 80-86, 8 figs.

Solem, A. In preparation. Characteristics of the Land Snail

Family Discidae Thiele, 1931.

Uminski, T. 1962 Revision of the Palearctic Forms of the

(Sen us Discus Fitzinger, 1833 (Gastropoda, Endodontidae).

Ann. Zoo/., Warsaw 20(16): 299-3:34. pis. 3-4.

Umiriski. T. 1963. Taxonomy of AnguLvpira (?) niarmoren.'iis

(H. B. Baker, 19:32) and Notes on the Taxonomy of the

Genera Anguispwa Morse and Difscu.s Fitzinger (Gastro-

poda, Endodontidae). Ann. Zool. Warsaw 21(9): 81-Sl,

19 text figs.

RANGE EXTENSION OF CORALLIOPHILA MARRATI KNUDSEN

(GASTROPODA: MAGILIDAE)

Henk K. Mienis

Department of Zoology, Hebrew University

Jerusalem, Israel

ABSTRACT

Coralliophila marrati Kmidsen. 1956 originally described from off Liberia is

here reported fro in Congo and Angola.

In his report on the molluscs collected during

the Atlantide Expedition to the coasts of

tropical West Africa, Knudsen (1956) described

three new species of the family Magilidae:

Coralliophila jarli, C. kraemmeri and C.

marrati. Although all were based on one or two

specimens, no doubt seems to exist concerning

the specific status of these species.

Coralliophila marrati was based on a single

specimen dredged from a depth of 78 m at 5°

06' N, 9° 34' W off Liberia. Since Knudsen's

description no additional data have been added

to the distribution of C. marrati.

The Zoological Museum of Amsterdam

acquired the second known specimen from Mr.

W. Bergmans. This specimen was collected in

1969 by J. Moret near Pointe Noire, Congo. It

agrees in full detail with the original descrip-

tion of Knudsen (1956: 29, pi. 2, fig. 14). It is

only slightly larger: height 26.7 mm; width 17.1

24 THE NAUTILUS

January 30, 1976

V(.l. 90 (1)

mm (respectively 21.9 and 14.7 mm in the

holotype).

The Hebrew University of Jerusalem

received recently a third specimen from Mr. J.

Bruynseels. This specimen was trawled at a

depth of 73 m on a coral bottom off Moita

Seca, Angola, in 1973. The measurements of this

specimen are: height 22.4 mm and width 14.1

mm. Another specimen from the same locality

is still in Mr. Bruynseels collection.

These two additional records of C. marrati

mean an important range extension in a

southern direction. It is, however, clear from

the known data that systematic dredging along

the coast of tropical West Africa may yield ad-

ditional specimens and localities of this rare

OiniUuiphUa.

I wish to thank Dr. H. E. Coomans and Mr.

R. Moolenbeek for their kind hospitality during

my visit to the Zoological Museum of Am-

sterdam. Thanks are also due to Mr. J. BruvTi-

seels (Belgium) for presenting the Hebrew

University of Jerusalem with one of the dis-

cussed specimens.

LITERATURE CITED

Knudsen. J., 1956. Marine prosobranchs of tropical West

.■\frica (Stenoglosa). Atlantide Report. 4: 7- lid.

CITTARIUM PICA (TROCHIDAE) IN FLORIDA

R. Tucker Abbott

Delaware Museum of Natural History

Greenville, Delaware 19807

Recent reports of living specimens of the

West Indian trochid, Cittarium pica (Linne), at

various localities along the shores of Marathon

and Molasses Keys seem to substantiate the

fact that this species has become established, at

least temporarily, along the Florida Keys.

Whether they were introduced by man from the

West Indies purposefully or accidentally, or

whether they arrived as floating larvae will

probably never be ascertained. Among the

earliest collectors were Mrs. Carol Brunner of

Miami (live, 30 mm.. Molasses Keys, October,

1973), Mrs. Betty Greene of Long Island, N. Y.

(live, 51 mm., oceanside of Ohio-Missouri

Key, March 9, 1974), Gary Magnote of Miami

(live, 80 mm.. East Sister Rock, Marathon, May

1975), and Robert J. L. Wagner of Marathon

(live, several, 100 mm., yacht basin at

Marathon, July 1975).

Clench and Abbott (1943) recorded only dead

shells from the Florida Keys, with the comment

that the species probably died out within com-

paratively recent times, perhaps due to low

temperatures. Verrill (1900) reported a similar

extinction of the species in Bermuda. On the

basis of Helen Randall's (1964) studies on the

growth rate of Cittarium. the 1973 specimens

from Molasses Keys may be assumed to be

about a year and a half old. Wagner's

specimens are about three years old. It is

possible therefore, that Wagner's specimens

came from a natural larval invasion sometime

during 1971 or 1972. Until other young

specimens, say under 10 mm in diameter, are

discovered it will remain a mystery whether or

not these are breeding populations. It will also

be interesting to see if an unduly cold winter

in the future will kill them.

Wagner ((>; Hit.) reported the nearby pres-

ence of "numerous" adult Pnri)um jHitiil(i{Linne).

a common Caribbean species usually thought to

be somewhat uncommon in the Florida Keys.

H. Randall (1964) reported that this snail is a

predator of Cittarium.

There have been sporadic records of large

adults found at various Florida localities, but

these may have been brought in from the West

Indies by fishing boats. A large live specimen

was collected in July 1948 at Dry Tortugas by

R. 0. Smith and was donated tti the U. S.

National Museum.

LITERATURE CITED

Clmvh. \\\ .] :uid R. T. Abbott. 194:J. The Genera Cmrt and

Liviimi in the Western Atlantic. .Inhmtiniia 1(12): M2,

4 pis.

Randall. Helen A. 19&4. A Studj- of the Growth and Gther

Aspects of the Biology of the West Indian Topshell,

Cittarium pica (Linnaeus). Bull. Mar. Sci. Gulf and Carib-

bean 14(.3): .12.1-143.

Verrill. A. E. 1900. Notes on the Geologj- of the Bermudas.

.Amrr. .hmr. Sci. 9(5.3): 313-.340.

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 25

COMMENTS ON EASTERN NORTH AMERICAN POLYGYRIDAE

Alan Solem

Department of Z(X)logy

Field Museum of Natural History

Chicago, Illinois 60605

ABSTRACT

Tlic (ictiitulia and mdular i^trncture of several Mesodon aiid Triodopsis from.

Arkansas, Okiahotna and West Virginia are iUustrated and dii<russed in relation

to their potential significance in phyloyenetic studies. Tlic stmrtnre of the

verge, penial pilaster details, penial sheath nni.'irle attachment, and details of

radnlar euspiny are emphamzed.

INTRODUCTION

During a survey of rare and potentially en-

dangered land snail species of Eastern North

America, numerous polygyrid land snails were

collected. Some of these previously had not been

dissected, others were studied in order to check

their affinities and compare their structures

with those of sympatric taxa. Although the em-

phasis here is on species from Arkansas and

Oklahoma, the opportunity is taken to include

information on the West Virginia Triodopsis

(T.) plaiysayoides (Brooks, 1933), since its struc-

tures differ from those found in Triodopsis

(Neohelix) alkdabris alleni (Wetherby, 1883)

and T. (N.) divesta (Gould, 1851). The main pur-

pose of this report is to review shell, genital,

and radular structures that can be confused on

the basis of shell structures and distributional

overlap. It is hoped that further work on their

ecology and relationships will be stimulated.

The field work by Mr. Glenn Goodfriend was

supported by Office of Endangered Species con-

tract 14-16-0008-764, which also paid for the ex-

cellent anatomical illustrations by Elizabeth A.

Liebman. OES contract 14-16-0008-965 provided

the page charges for publication. The scanning

electron microscope photographs of radulae and

jaws were taken by the author with a Cambridge

S4-10 Stereoscan provided to the Field Museum

of Natural History by NSF Grant BMS72-02149

AOL The SEM prints were prepared by Fred

Huysmans. I am indebted also to Leslie Hu-

bricht for loaning material of Triodopsis

platysayoides, to Katy Baker for help with

literature compilations, and to Jayne Freshour

for aid with manuscript preparation. The OES

staff, particularly Marc Imlay, has been most

helpful and encouraging in these efforts.

STATUS OF KNOWLEDGE

Explorations for land snails in Missouri,

Arkansas and what is now Oklahoma were

carried out by James Ferriss in 1900 and 1901,

and then by Henry A. Pilsbry and Ferriss in

1903. The papers by Pilsbry (i903) and Pilsbry

and Ferriss (1907) contain data that is still

essential for any field work in this region,

although their major findings were summarized

by Pilsbry (1940) in his monograph of the

Polyg>Tidae. This work, which synthesizes the

efforts of a century, remains the basic reference

for work on the family. Subsequent faunistic

and descriptive papers by Leslie Hubricht, B.

Branson, L. Lutz and others have provided ad-

ditional distributional records. The conchological

review of Triodopsis by Vagvolgyi (1968), and

the review of the T. fallax group by Wa>Tie

Grimm (1975) contain much useful information.

Potentially the most significant studies are

those of Glenn R. Webb (1952, 1954a, 19.54b,

1959, 1961, 1974) on mating behavior and

anatomy. Unfortunately these papers are dif-

ficult to use. Webb's supraspecific taxa were

ignored by Vagvolgyi (1968) and Grimm (1975).

The subgeneric and sectional names Wilcoxorbis

(Webb, 1952), Aphalogona and Ragsdaleorbis

(Webb, 1954b), Haroldorbis and Shelfordorbis

(Webb, 1959), and the subfamily Ashmunellinae

(Webb, 1954a) are validly proposed taxa and

must be included in any revision of polygyrid

classification.

26 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

The characters that have been used to define

supraspecific categories are few in number.

Mostly they involve alternative states, such as:

penis sheath and retentor muscle (present or

absent); epiphallus (present, absent or vestigial);

duct of spermatheca (slender or swollen); verge

(present or absent); number of major pilasters

inside the penis (one or two); and the size of

a-d

e-h

FIG. 1. ,.S7(('//.s- (if Charkian Pohjgyridae: a-b, Ti-iodopsis

albi)labris alleni (Wctherbii). FMNH 176127. Tenktllcr State

Park. Sequmjah Co.. Okluh<wui: c-d, Mesodon binneyanus

(Pihbni). FMNH J76008. Rich Ml.. Polk Co.. Arkansax: e-f.

Mesodon clausus (Say). FMNH 176220. Calico Hock, hard

Co., Arkan.iax: g-h, Mesodon clenchi (Rehdvrj. FMNH

176059. Mt. Neho State Park. Yell Co.. Arkaiigas. Scale lines

equal ID mm.

Vol. 90 (1)

Januarv 'M). 1976

THE NAUTILUS 27

FIG. 2. Shell o/'Triodopsis divesta (Gotdd). FMNH UfiOHi. Magazine Mt.. Lix/an Co.. Arkaiisa.^. Scale line eqiiah 10 mm.

the papillae in the upper chamber of the penis.

Although Pilsbry (1940: 703) had pointed out

that the finer structure inside the penis should

be investigated, subsequent workers have

ignored this suggestion.

Diodopsis platysayoides and Mesodon clenchi

(Rehder, 1932) had not been dissected

previously, and only fragmentary data had been

published concerning the structures of Ttiodop-

sis divesta and Mesodon dausus (Say, 1821).

New details on the structures of Mesodon bin-

neyanus (Pilsbry, 1899) and Triodopsis

albolabris alleni are presented.

SHELL CHARACTERS

The absence of any major shell differences

between species of Mesodon. Ttiodopsis, and

Allogona that lack apertural barriers has con-

fused students and collectors of the group for

more than a century. Particularly in the

Ozarkian region, several Mesodon and Ttiodop-

sis are conchologically quite similar. They have

differences in the lip and umbilical region, but

most previous illustrations fail to show these

features. New line drawings are presented here

to demonstrate such distinguishing characters.

Triodopsis (Neoheiix) albolabris alleni

(Wetherby) is highly variable in size and color,

ranging as adults from 17-32 mm. in diameter.

The relatively depressed spire, fairly sharp

descension of the body whorl just before the

aperture (fig. 1 a), presence of a thickened

ridge on the basal lip (figs. 1 a, b), and sharply

defined union of the columellar region to the

umbilical covering (fig. 1 b) present a distinct

contrast to the Mesodon (figs. 1 c-h). Triodopsis

(Neoheiix) divesta (Gould) generally is much

smaller in size, mostly 17-21 mm. in diameter.

has a distinctly weaker ridge on the basal lip

(fig. 2 left), shows only slight descension of the

body whorl near the lip, and has a very

gradual merging of the columellar lip into the

umbilical covering (fig. 2 right). Small

specimens of T. a. alleni can be confused with

normal T. divesta, but the differences outlined

above are sufficient to enable identification.

Mesodon binneyamis (figs. 1 c-d) and M. clen-

chi (figs. 1 g-h) differ from each other most ob-

viously in umbilical size, degree of lip reflec-

tion, and body whorl thickness, while M.

clausius (figs. 1 e-f) has a higher spire, narrow

lip, and a more angular insertion of the

columellar lip (fig. 1 J). There is partial size

overlap among these species. M. clausus (10-20

mm. in diameter) normally is smaller than M.

hinneyatiux (16-28 mm.) and M. clenchi (19-23

mm.).

In many places three or more of the above

species are sympatric, at least to the extent of

living on the same slope or in the same ravine.

A compilation of recorded localities in Arkan-

sas, Oklahoma and Missouri for T. divesta, T. a.

alleni, and M binneyanus, for example, showed

that for the 35 T divesta localities, T. a. alleni

also was recorded from 16 of these. Of the 23

localities known for M. binneyanus, T. a. alleni

also has been taken at five, T. divesta at two,

and at an additional two localities, all three

species have been collected. The exact ecological

relationships between these species are

unknown, and a comparative ecological survey

would be well worthwhile.

TERMINAL GENITALIA

The degree to which the terminal genitalia

function in "species recognition" and the extent

28 THE NAUTILUS

January 30, 197fi

Vol. 90 (1)

to which major differences in structures of this

region make hybridization difficult or unlikely

vary greatly from group to group of land

snails. Webb (1952. 1954a, 1954b, 1959, 1961.

1974) has published voluminously on mating

behavior and anatomies of polygyrid snails,

with the cited references only serving as a

locator for his studies. Grimm (1975) reported

evidence of hybridization in the field and many

laboratory crossings among Triodopm, s. .s. The

situation in polygyrids is quite complex. All

this report can do is to focus on some struc-

tural features for future investigation and to

report on some previously undissected species.

leather than present formal descriptions, com-

ments are restricted to comparisons between

structures in order to emphasize features with

potential phylogenetic significance and of use in

classification.

The classic key difference between Mei^adnn

and Ttiodopsis involves the presence in the lat-

ter of a penis sheath (PS) and a continuation

of the penial retractor muscle (PR) from its in-

sertion on the vas deferens (VD) or penis (P)

apex to the penis sheath. This continuation

sometimes is called the "penis retentor

muscle". The length of the sheath varies

greatly, being long in T. plaiysayoides (fig. 3 6),

short in T. divesta (fig. 4 6), and intermediate

in T. a. alleni (fig. 5 a). These differences were

constant in the materials examined. The sheath

in T. plaiysayoides (fig. 3 b) also has a very

unusual muscle attachment, in that it essen-

tially spreads completely around the penis and

onto the inside of the sheath, whereas in the

other species it fastens to one portion of the

sheath wall (fig. 4 b). All Triodopsis dissected

to date agree in having two sections to the penis.

'r\\e upper chamber has one very large pilaster

plus a large microsculpture of papillae, while

the lower chamber, the area below the apex of

the penis sheath, has a series of simple

longitudinal pilasters (PP) that continue into

the atrium (Y). The relative length of the two

chambers varies from species to species (com-

pare figs. 3, 4, 5) and the lower chamber

sometimes shows a distinct difference in

pilaster size below the penis sheath when com-

pared with the area of the penis sheath (com-

pare figs. 3 b. 4 b).

There are obvious and major differences in

the size and spacing of the papillae in the up-

per penis chamber (see figs. 3, 4 and 5). What

has not been recorded previously, is the

variation in apical penis structures. Although

Xolntrema and Neohelix were reported to have

verges (Webb, 1952), any differences in verge

size and form were not recorded or illustrated.

In T. platysnyoides (fig. 3 6) there is no trace of

a verge, while in T. a. alleni (fig. 5 a) the verge

fk;. 3.

Cooper ';

Gciiilnlia (if Ti-iodopsis (T.) platysayoides (Bnmks).

Rdi-k. MniKifidlid C(i.. West Virginia. Leslie

Huhrichl lliStiO: a, tcnnimil iji'ii'dulm: b, iiitcrior af penis

and penis shenlli. Scale lines equal .5 mm.

Vol. f)n (1)

Januarv 30, 197fi

THE NAUTILUS 29

FIG. 4. Genitalia of Triodopsis (Neohelix) divesta (GnuU). minal gcnitatin: b, interior of penis and penis sheath. Scale

FMNH 1/6082, Magazine ML. Logan Co., Arkansax; a, ter- lines eqnal .5 mm.

FIG. 5. Genitalia of Triodopsis (Neohelix) albolabris alleni

(Wetherby) and Mesodon (M.) clenchi (Rehderj: a, c, T. (N.)

a. alleni. FMNH 176127. Tenkiller State Park, SequoyaJi Co.,

Oklalumin. a, interior of peni.s; c, tenninal genitalia: b, d.

M. (M.) clenchi (Rehder). FMNH 176059. Mt. Nebo State

Park, Yell Co., Arkansa.'i; b, juvenile tenninal (/enitalin; d,

ivierior of apical penis region. Scale lines for a-c equal. 5

mm., scale line for d equals 1 mm.

30 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

FIG. 6. Genitalia of Mesodon (M.) clausus (S(niJ. FMSH I7(L'M Calim A'r»A-. hrird Oi.. Arkansas: a, iidiitnlla: b, iiitprior

of penis. Scale lines equal 5 mm.

(PV) is a very large, conical structure with ter-

minal pore. In the often sympatric T. divesta

(fig. 4 b). the verge is a flap-like opening to one

side of the slightly recurved main pilaster and

the pore (PVO) is quite large. The differences

in chamber lengths, papillae size and number,

and verges between T. a. dleni and T. divcsta

probably are sufficient to prevent hybridization.

Equally significant variations can be found in

species of Mesodon. M. clauaus (fig. 6 h) has a

vergic papilla through which the vas deferens

opens and only a single elevated pilaster (P);

M. denchi (fig. 5 d) has two pilasters of equal

size and apparently no vergic papilla; and M.

hinneyanm (fig. 7 e) has two unequal pilasters

that join apically into a flap-like arrangement,

but with the vas deferens entering through a

simple ixire (DP) above the pilaster junction. A

talon (GT) is well developed in M. hinneyanus

(fig. 7 b), but is only a reflexed area in M.

clmisua (fig. 6 a), without being differentiated

from the hermaphroditic duct (GD). All

examined Mesodon had a relatively long vagina

(V), short free oviduct (l^V), spermatheca (S)

with slender shaft, finger-like albumen gland

(GG) and showed no unusual features in the

prostate (DG) and uterus (UT). The ovote.stis

(G) of M. clausus (fig. 6 a) is illustrated, but

most other taxa had this organ in a reduced

stage and it was not studied.

Mesodon binnei/anii.^ (fig. 7) has a very large

penis that is substantially longer than the shell

diameter. Pilsbry (1940: 740. fig. 445, D) used

cross-sections of the penis to establish basic

structures. The more detailed drawings presen-

ted here provide further details of structure.

The apical portion (fig. 7 e) has a short, lower,

second pilaster that gradually merges into the

penis wall. The main pilaster is very high, thin,

and apically forms a flap-like stimulator. In

mid-penis (fig. 7 c) the main pilaster is reduced

in height, thicker, and there are no obvious

subsidiary structures on the penis wall. In the

basal section (fig. 7 d) the main pilaster is

almost circular in shape, becoming flatly ovoid

at the atrium, and there is a complex set of

minor pilasters on the penis wall. Unlike the

situation in M. clausus (fig. 6 b) there is no

pilaster-ft-ee basal area to the penis.

JAW AND RADULAR STRUCTURE

A strongly ridged jaw with denticulated

lower margin is characteristic of the

Polyg>-ridae. No study of jaw variation in rib-

bing or microstructure has been published.

References to the jaw usually are restricted to

V.il. 90 (1)

Janiuirv :M). li»7«

THE NAUTILUS 31

FIG. 7. Genitalia of Mesodon (M.) binneyanus /Pilxhnj).

FMNH 176008. Rich Mt.. Polk Co.. Arkansas: a, tei-mind

!/i'iiitnli<i: b, apical genitalia excltutive of omte.'iti.t: c, in-

terior of mid-penis region: d, interior of basal portion of

penis: e, interior of penis apex. Scale tines equal 5 mm. for

b-e and 10 mm. for a.

a few outline sketches indicating rib numbers

(see Pilsbry, 1940: 912, fig. 522). The jaw of

Triiidopfiis alholabris alleni (figs. 8-10) is

illustrated here to show the typical shape (fig.

8), to demonstrate the wear surfaces on the

denticulated lower margin (fig. 9), and to in-

dicate that the jaw structure is fibrous in

nature (fig. 10). Examples of the other species

studied showed no significant differences. In-

deed, the jaw microstructure is very similar to

that of the helminthoglyptid Humboldtiana

fuUingtoni Cheatum, 1972 from Texas (see

32 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

Solem, 1974: figs. 3-5). Both series of

photographs clearly show the horizontal in-

cremental pattern of jaw growth and demon-

strate the interlocking, basically vertical orien-

tation of the microfibers.

Radular data on polygyrids is equally

FIGS. 8-13. .laie and niduhv tfpth. Figs. 8-10. Jaw of

Tri(x)opsis (Nfohelix) albolabris alleni (Wetherby). FMNH

176127. Fig. 8. Kntirc jaw. lower maryiii nt top of fiipirr.

9JX. Fig. 9. Detail if two ridi/es on lower niaryiri atid in-

ter-ridge area. ■i75X. Fig. 10. Fibrous area between tiro

ridges shown in Fig. 9. greatly etdarged. 5.725X. Figs. 11-12.

Radular teeth of T. (N.) a. alleni (Wetherby). FMNH

17(il27. Fig. 11. Transition zone between lateral (upper) and

marginal (lower) teeth near p<isterior end of nulula. ■I7I)X.

Fig. 12. Central (tricuspid) and early lateral teeth. 62.5 X.

Fig. 13. Central and early lateral teeth of Triodopsis (T.)

platysayoides (Brooks). Leslie Hubriclit 11860. 350X.

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 33

meagei'. Pilsbry (1940: 703) summarized report-

ed variation in Mesodon, where several species

apparently lack ectocones. I suspect that this is

partly individual variation and partly results

from the deficiencies of optical viewing.

Mesodoii clausus, for example, is supposed to

lack ectocones on all but the outennost

marginals, yet traces can be seen (figs. 26-27)

on the first laterals and there are prominent

ectocones on the outer teeth (figs. 28-29). M

r/(;//.svw does differ in having the cusps on the

outer marginals serrated (fig. 29), but even this

may be subject to individual variation.

The prominence of the side cusps on the

rachidian (central) tooth vary from the large

and conspicuous ones found in M. clenchi (up-

nO%^-

-•^^^^

^

17

FIGS. 14-19. Kadular teeth. Figs. 14-17. Triodopsis (T.)

platysayoides (Bmoks). Leslie Huhrieht IlfiiKl. Fig. 14. Part

nnr itf teeth, not including miter marginals. UOX. Fig. 15.

Tinnsitian zcne between laleral.'i and maniiiials. .!J,.5X. Fig.

16. Outer marginals. 355X. Fig. 17. Outermost marginals.

.i.55X. Figs. 18-19. Mesodon (M.) binneyanus (Pilsbry). FM-

NH 176008. Fig. 18. Outermost marginals. S.S2X. Fig. 19.

Transition betiveen laterals and marginals. Si2X.

34 THE NAUTILUS

January 30. 1976

Vol. 90 (1)

FIGS. 20-25. Rmhdar teeth. Figs. 20-21. Mesodon (M.) bin-

neyanus (Pil.ibryj. FMNH 171101)8. Fig. 20. Central and 1st

lateral teeth. 670X. Fig. 21. Ti-ansitional between lateral

(upper left) and man/inal (lower right) teeth. S95X. Figs.

22-25. Mesodon (M.) clenchi (Rehder). FMNH 176059. Fig.

per left of fig. 22) and THodopsis albolabris

alleni (fig. 12), to a total absence in T.

platysayoideK (fig. 13). M. dmmis (fig. 26) and

M. binneyanua (fig. 20) are intermediate in cusp

prominence. Ectoconal size on the early lateral

teeth correlates with the side cusp prominence on

the central tooth. If the central tooth has

prominent side cusps, the laterals have a

prominent ectocone, and small cusps occur on

22. Central and early lateral teeth. 762X. Fig. 23. Ti-an-

sition between lateral (left) and marginal (right) teeth.

.505 X. Fig. 24. Transitional change in basal plate structure

between laterals (left) and marginals (right) 5-i5X. Fig. 25.

Outermost marginal teeth. SOOX.

both at the opposite extreme (see figs. 12, 13,

20, 22, 26). These same illustrations show that

the pattern of interrow tooth support for the

central and early lateral teeth is nearly iden-

tical. The anterior flare on a lateral tooth un-

der stress fit neatly into a groove on the outer

side of the basal plate on the next anterior

lateral tooth (see figs. 12, 13, 20, 22, 26, 27).

The central tooth has a raised buttress on each

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 35

FIGS. 26-29. Radular teeth of Mesodon dausus (Say). FM-

.\H 176220. Fig. 26. Centnd and fiist lateral teeth. 59.5X.

Fig. 27. Central and early lateral teeth seen from a law

posterior iriewing angle. 1,25'K. Fig, 28. Transition between

laleral and marginal teeth. .J?.5X. Fig. 29. Mid-marginal

and outer marginal teeth. 365X.

side of the basal plate. Because of the angle at

which these photographs were taken, the im-

pression is given that the anterior flare of the

lateral tooth is not or only slightly curved up-

wards. In fig. 23, the angle of view is such that

the upward curve (see left side of photograph)

of the anterior flare is more evident.

The change from lateral to marginal teeth in-

volves a number of alterations. Fig. 11 shows

clearly the higher angle of the cusps in the

laterals (upper), with the change to a much

lower angle in the marginals (lower) occurring

in just a few teeth. Seen in more vertical view

(figs. 14, 1,5, 19, 21, 23, 28), the coherent pattern

of cusp change that involves narrowing and

elongating the mesocone, an increase in ec-

toconal prominence, change in shape for the an-

terior flare, often (figs. 15, 28) a centerwards

shift in angle for the mesocone, and appearance

of a small endocone, is clearly demonstrated.

The change in the basal plate, which involves

shortening, first reduction and then loss of the

support ridge, then gradual elimination of the

anterior flare, is shown in figs. 24 and 28 par-

ticularly well because of the viewing angle (fig.

24) and partly torn radula (fig. 28).

The marginal teeth, particularly the outer-

most (figs. 17, 18, 23, 25, 29) ones, can become

multicuspid, normally show endoconal develop-

ment, and may become quite shortened and

probably are almost without function in

feeding. They are held parallel to the basal

membrane, which is quite in contrast to the

high elevation of lateral teeth (figs. 11, 20).

In terms of basic structure and pattern of

functioning, the radulae examined here show no

major differences between species, much less

between genera. The different angles of view do

permit interpreting functional aspects. Several

species have been illustrated to emphasize their

essential similarity.

DISCUSSION

Particularly within Triodopais, the variation

in verges, papillae of the upper penis chamber,

penis sheath length and muscle attachment,

present characters potentially of high value in

assessing relationshif)s. Radular cusp variation

36 THE NAUTILUS

January 3n. 1976

Vol. 90 (1)

is greater within Mesodon and TriodopsiH than

between the two genera. Shell differences be-

tween the svTnpatric taxti involve growth pat-

terns and rolumellar-umbilical region structures.

Triodopsis platysayoides is a rare and pf)ten-

tially endangered species, but Mefmdun clenrhi

was found to be more widely distributed than

had been suspected and it seems in no danger

of extinction at the present time. The other

species discussed here have wide distributions

and may be considered common at the present

time.

Because the barrier-free Mes^odon and

Tfiodopds of Missouri, Arkansas and Oklahoma

are widely distributed, frequently sympatric.

usually highly variable in size and rolor, they

present excellent potential for studies of

ecological differences under sympatry and for

variational analysis.

LITERATURE CITED

Grimm, F. W. 197.5. Speciation Within the Tiiodapxis fdUu

Group (Pulmonata : Polygyridae)— A Preliminary Re-

port. Bull Amn: Malac. Unimi. Im:. 1974: 23-23, .3 figs.

Pilsbry. H. A. 190.3. Mollusca of Western Arkansas and

.Adjacent States, with a Revision of Paravitrea. Pnc.

Aaul. Nat. Sei.. Philadelphia, 1903: 19.3-214. pis. 9-11.

Pilsbri', H. A. 1940. Land Mollusca of North America

(North of Mexico). Acad. Nat. Sci.. Philadelphia. Monog.

.3. 1(2): iii-vi, 575-994, figs. 278-580.

PiLsbn.'. H. A. and .J. Ferriss. 1907. Mollusca of the Ozark-

ian F^auna. Proc. Acad. Nat. Sci.. Philadelphia. 1906:

.t29-.%7. pis. 20-22, figs. 1-.5.

Solem, A. 1974. On the Affinities of Humhuldtiana fulling-

timi Cheatum. 197Z TYie Veliger, 16(4): .359-.36.5, figs. 1-14.

Vagvolgyi, .J. 1968. Systematics and Evolution of the Genus

Trii}d(ipsis (Mollusca : Pulmonata : Polygyridae). Bull.

Mux. Cmnp. Zmi. 136(7): 145-254, pis. 1-6. figs. 1-27.

Webb, G. R. 1952. A Sexological Revision of Some Trio-

dopsin land-snails, Xidotrema, Neohetic. & WUaixorbis.

(kuitnipiidia. 1(1): 7-8.

Webb. G. R. 19.54a. The Life-histor>- and Sexual .Anatomy

Data on A.'ihmunella with a Revision of the Triodopsin

Snails. Gastropudia, 1(2): 1.3-18.

Webb. G. R. 1954b. Pulmonata, Polygyridae, Polygyrinae :

TTie Sexology and Taxonomy of Seven Species of Land-

snails of the Genus Mesodon. Gastropudia, 1(2): 19-21).

pi. 12.

Webb. G. R. 19.59. Notes on the Sexolog>' of 7>Ti(/'ip.<fi.s. a

New Subgenus, Haraidnrhi^t. and a New Section, She!-

thriliirbi.i. (hxtnipodin. 1(3): 2.3-2.5.

Webb. G. R. 1961. The Phylogeny of American I^nd Snails

with Emphasis on the Polygyridae. Arionidae. and .Am-

monitellidae. Gastrtipadla. l(4-.5): 31-44.

Webb, G. R. 1974. The Sexual Evolution of the Polygyrid

Snails. Gn.'^tmp.dia. 1(9): 8.5-f)0.

TREMATODE PARASITISM IN THE SPHAERIIDIDAE CLAMS,

AND THE EFFECTS IN THREE OTTAWA RIVER SPECIES

G. L. Mackie

Department of Zoology. University of Guelph,

Guelph, Ontario, Canada

NIG 2W1

ABSTRACT

TJiere /.s a seasonal occurrence of rediac of the trematode. CrepidostoniimT

cooperi Hopkins, in the diqestive gland of Musculium securis (Prime) in Britan-

nia Bay of the Ottawa River near Ottawa, Canada. Growth and longevity of in-

fected clams do not appear to be affected hut reproduction is iisiialh/ inhibited.

Similar effects seem to occur in parasitized specimens of Musculium trans-

versum (Scrii) and Sphaerium striatinum (Loman-kl. A rericir if the incidence

of trematode parasitism in Sphaeriidae is given.

INTRODUCTION

While the incidence of trematode parasitism

in Sphaeriidae is well documented (see Table 3),

there is very little known on the effects of this

parasitism. The purpose of this study is to

examine the effects of trematode parasites on

growth, longevity, and reproduction in

Musculiiim securis, Musculium transversum, and

Sphaerium striatinum that were collected

seasonally from Britannia Bay in the Ottawa

!•() (1)

January 30. 1976

THE NAUTILUS 37

River near Ottawa. A review is given to bring

together all studies that relate to trematode

parasitism in Sphaeriidae.

MATERIALS AND METHODS

A standard Ekman grab (L5 cm X 15 cm,

with screen on top) was used to take quan-

titative samples of the population of M. securis.

Grab samples were taken from the 3 to 4 m

depths until at least 30 specimens were collect-

ed. Collections were taken for three years from

May, 1970 to May, 1973 in usually two-week in-

tervals in the summer and one-month intervals

in the winter. A total of 1,764 specimens of M.

securis were examined for trematode parasites.

In addition, 123 specimens of M. transversiim

and 158 specimens of S. striatimim were collect-

ed from the 1 to 3 m depths in the same man-

ner from May to November, 1971 and 1972,

respectively, and examined for parasites. The

lengths (mm, anterior to posterior), heights

(mm, top of umbone to ventral edge), number

of concentric annuli (for S. striatimim only),

and the numbers of brood sacs and larvae per

sac were determined on all specimens (the num-

ber of annuli were not determined for M.

securis or M. trcmsversum because they have

only a one-year life span).

THE STUDY AREA

Fifteen species of sphaeriids are present in

Britannia Bay; M. transversum and S.

striatinum are common species in the 1 to 3 m

depths and M. securis is dominant in the 3 to 4

m depths (Mackie, 1971; Mackie and Qadri,

1973). Other common benthic species include the

oligochaetes, Urwinais undnata and Peloscolex

sp., the amphipods, Hyalella azteca and Gam-

mants fasciatiis, the mayfly, Hexagenia sp.

(especially in the 3 to 4 m depths), the dam-

selfly, Enallagma signatum, the chironomids,

Pseudochironomus, and Dicrotendipes, and the

gastropods, Lymnaea catascopium, Amnicola

limosa, and Valvata tricarinata. The mean sum-

mer temperature (18 C) is reached in mid-June.

Other physical and chemical characteristics of

the water are given in Mackie (1973). Several

species of fish are present in Britannia Bay,

the most common being catfish, Ictalurus punc-

tatus, walleye, Stizostedion vitreum, and pike,

Esox lucius.

EFFECTS OF PARASITISM

The trematodes in M securis and M. trans-

versum were identified as Crepidostomum

cooperi Hopkins, 1931. A specific identification

of the trematodes in S striatinum was not

made but they also belonged to the genus,

Crepidostomum. Redial stages were found

developing only in the digestive glands. No

other life history stages were found. The rediae

contained ophthalmoxiphidiocercariae which

escape into the water and encyst in mayfly

njTTiphs (Gibson, pers. commj. Hopkins (1934)

cites Hexagenia sp. as the second intermediate

host of C. cooperi; this genus is very common

in Britannia Bay, especially in the 3 to 4 m

depths. Adults of C. cooperi are common in

many species of fish, including catfish and

walleye (Gibson, pers. comm.) which are also

abundant in Britannia Bay.

There was a seasonal occurrence of the redial

stage in M. securis (Table 1) and only adults

longer than 3.50 mm were infected. An in-

sufficient number of M. transversum and 5.

striatinum were infected to permit a deter-

mination of seasonal occurrence of parasitism

but only adults longer than 5.00 mm contained

rediae. In M securis, parasitism occurred with

maximum frequency in late July and early

August. The percentages given in Table 1 are

based on infected adults that were alive at the

time of sampling. Empty shells of M. securis

commonly appeared in samples collected in July

TABLE 1. Percentayc of parents of Musculium securis that were parasitized in the simmer months of 1970. mi. 19/2. Only

dams collected in .My. August, and September were para.<titized uith rediae.

38 THE NAUTILUS

January 'M), 1976

Vol. 9(1 (1)

TABLE 2. Mean lenythx (mm) nf three, species of parasitized and luinparasitized fingernail clams in their last month of life

or with (me anmdxts. The numbers of specimens examined are in jxirentheses.

Species

Nonparasitized clams

Parasitized dams

Mtiscidium secmis

Miisculiuni transversum

Sphaeriitni siriatinum

4.09 (38)

7.81 (24)

10.10 (.32)

4.39 (12)

7.63 (8)

9.77 (5)

and August but it is not known whether

natural causes or parasitism brought about the

death of these clams. Only 16% of M trans-

vermim and 12% of S. stiiatinum were in-

fected. The only parasitized clams of M. trans-

versum were found in collections taken in July

and August and of S striatinum in September

and October.

Adult specimens ofM securis as long as 5.50

mm, of M. transversum as long as 8.13 mm,

and of S striatinum as long as 9.05 mm were

parasitized, suggesting that parasitism did not

affect the growth of clams. Moreover, the mean

lengths of parasitized and nonparasitized clams

did not appear to differ substantially (Table 2),

although it is possible that infected clams had

been parasitized only recently. However, if

development of the intramoUuscan phase

requires only 40 to 50 days, as for many

gorgoderids which also parasitize sphaeriids

(Olsen, 1967), then M. securis and M. trans-

versum would have to be parasitized very

early in life, perhaps even during larval life,

since they require 35 to 60 days to grow from

birth to adulthood (Mackie et al. 1975; Gale,

1969).

Both M. securis and M transversum have a

one-year life span and the adults die in the fall

after producing their young (Mackie et al. 1975;

Gale, 1969). The presence of parasitized adults

of both species during August indicates that the

longevities were not strongly affected by

trematode parasites.

Sphacrium striatinum lives for 18 to 24 months

(Avolizi, 1971) and it was more difficult to

study the effects of parasitism on growth and

longevity because of overlapping generations in

Britannia Bay. However, using annuli in the

shell as an indication of age, adults that were

more than one year old were parasitized but

were of similar size as the noninfected clams

(Table 2). If these clams were parasitized only

recently then parasitism occurred so late that

the growth of the clams would have been

almost complete and any effects of parasitism

on growth and longevity would not have shovm.

Parasitism by C. cooperi appears to have its

greatest effect on the reproductive capacities of

sphaeriids. Of the parasitized adults of M.

securis, approximately 96% were devoid of

brood sacs; the remaining 4% contained brood

sacs but larvae were either absent or poorly

developed. Uninfected adults of the same age

and length class contained 3 to 6 brood sacs

with 2 to 8 larvae per sac. Also, the gonads

could not be found in two parasitized clams.

All other parasitized specimens appeared to

have their gonads intact. It was not determined

if gametogenesis in the intact gonads was

inhibited as in other mollusks (Cheng and

Snyder, 1972).

Of the parasitized adults of M. transversum

and S. striatinum none contained brood sacs

even though nonparasitized adults of the same

size classes were gravid with 2 to 14 larvae in

3 to 6 brood sacs. Gale (1973) also reported the

absence of embryos in parasitized clams of M.

transversum. Cheng and James (1960) attributed

the death of adults of S. striatinum to the

destruction of the clam's hepatopancreas after

repeated infections with Crepidostomum cor-

nutum. Other sphaeriids appear to be similarly

affected. Meier-Brook (1970) found larval

trematodes in Pisidium nitidum, Pisidium sub-

tnirwatum. Pisidium milium, and Pisidium con-

ventus and concluded that Crepidostomum sp.

affects the reproductive ability (and longevity)

of P. nitidum. Heard (1965) reported a lack of

embryos in parasitized specimens of Psidium

casertanum and Pisidium compressum. The ef-

fects of larval trematodes on other bivalve and

gastropod hosts has been reviewed by Cheng

and Snyder (1972).

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 39

REVIEW OF TREMATODE PARASITISM IN

SPHAERIIDAE

Sphaeriids are common intermediate hosts for

several species of digenetic trematodes. Only

two families, the Allocreadiidae and

Gorgoderidae, contain species that require

sphaeriids for development of the sporocyst,

rediae, and/or cercariae.

In the family, Allocreadiidae, miracidia

penetrate the gill filaments and the mantle

where they transform into sporocysts (although

this developmental stage has never been found

(Olsen, 1967)) and then into rediae. The rediae

contain either daughter rediae or cercariae, or

both, with large rediae usually infesting the

hepatopancreas (Olsen, 1967). The cercariae,

having eyespots, a stylet, and thick-walled

excretory vesicle are known as ophthal-

moxiphidiocercariae (Schell, 1970). At least

13 species of allocreadiids use sphaeriids as

the first intermediate host. Table 3 lists the

species of Sphaeriidae in which parasites have

been found and gives the second intermediate

hosts and final hosts for each parasite.

The miracidia of the family Gorgoderidae are

active swimmers and enter fingernail clams in

the incurrent water flowing through the bran-

chial siphon. Upon penetrating and entering the

TABLE 3. Incidence nf trematode parasitism in Sphaeriidae and other hosts nf the parasites.

'Cited by Schell (19«7| as ,W ryckJwlti

' Cited by Goodchild (19431, Groves (194.5), and Choquette (1954) as P. abditum

' Cited by Hoffman (1955) as P. m>V€ixtnucense

40 THK NAl'TILUS

January 30, 1976

Vol. 90 (1)

gills, the miracidia transform to mother

sporocysts. Development of daughter sporocysts

requires 40 to 50 days. The daughter sporocysts

become ventrally located between the inner and

outer lamellae of the inner gills of the clams

and contain fully developed cystocercous cer-

cariae. The cercariae have a tail with a cham-

ber at one end and encloses the larval fluke.

The cercariae are released into the suprabran-

chial chamber of the clam and are then ex-

pelled with the excurrent water through the

anal siphon (Olsen, 1967). At least 7 species of

gorgoderids require sphaeriids as the first in-

termediate host (Table 3).

From a study of Table 3, it is worthwhile

noting that, with the exception of only a few

species, especially C. cooperi. only one parasitic

species has been found in a single species of

sphaeriid. This may indicate that either there is

some degree of host specificity or that an in-

sufficient number of sphaeriid populations have

been examined to show that there is in fact

more than one parasitic species of trematodes

per species of fingernail clam.

ACKNOWLEDGMENTS

The author is grateful to Dr. G. Gibson of

the Canadian Wildlife Services, Environment

Canada, Ottawa, and to Dr. M. Beverley -Burton

of the University of Guelph for identifying the

parasites. A portion of this research was done

at the University of Ottawa, Ottawa, on Grant

No. A-2386 awarded to Dr. S. U. Qadri by the

National Research Council of Canada. A large

portion of the research was supported by the

Research Advisory Board, University of Guelph,

Grant No. 695-16.

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Ameel, D. J. 1937. The life history of Crepidostomum comu-

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Anderson, G. A., S. C. Schell, and I. Pratt. 196.5. The life

cycle of HuiuKhrcUn mvtti'ri (."Miocreadiidae: Bunoderi-

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Avolizi, R. J. 1971. Bioma.ss turnover in natural popula-

tions of viviparous sphaeriid clams. Ph.D. thesis. Syracuse

Univ., Syracuse, New York. 154 p. Univ. Microfilm No.

71-23429, Ann Arbor, Michigan.

I5eilfuss, E. R. 1954. TVie life histories of Phi^lndistomum

Idhrfiizi Ijoewen, 1935, and P. caudaium Steelman, 1938

(Trematoda: Gorgoderinae). Jour. Piirasit. 40 (Sect. 2):

44.

Brown. F. J. 1927. On Crepuitistiimum farionis 0. F. Mull.

{=Stfpliani>phiala laureata Zeder), a distome parasite

of the trout and grayling. I. The life history. Parasitology

19: 86-99.

Cheng, T. C. and H. A. James. 1960. The histopathology of

Crepidostomum sp. infection in the second intermediate

host, Sphaerium striatinum. Proc. Helminth. Soc. Wash.,

27: 67-68.

Cheng, T. C. and R. W. Snyder, Jr. 1962. Studies on host-

parasite relationships between larval tremat(xies and

their host.s. I. A review. II. Host glycogen utilization by

the intramollu.scan larvae of Gli/pthetmins pennsylvanien-

sis Qieng and associated phenomena. Trans. Amer. Mi-

crosc. Soc. 81: 209-228.

Choquette, L. P. E. 1954 A note on the intermediate hosts

of the trematode, Crepidostomum coopen Hopkins. 1931.

parasitic in speckled trout (Stdvetinus fontmalt.s Mitchell)

in some lakes and rivers of the Quebec Laurentide Park.

Can Jour. Zool. 32: 375-377.

Crawford. W. W. 1939. Studies on the life histories of Colo-

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194()b. The life historj- of a gorgoderid trematode,

presumably of the genus PhyHodistonmm. Jour. Parasit.

26 (Sect. 2): 38.

Degiusti, D. L. 1962. Ecological and life historj- notes on

the trematode AUocreadium lobatum (Wallin. 1909) and

its occurrence as a progenetic form in amphipods. Jour.

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Dollfus, R. 1949. Sur une cercaire ophthalmoxiphidiocerque

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1973. Predation and parasitism as factors affecting

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Vol. 9(1 (1)

January 30, 1976

THE NAUTILUS 41

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1973. Biology of Muscidium sectiris (Pelecypoda:

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Intraspecific variations in growth, birth periods, and

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136-142

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THE GENUS EPIROBIA IN CHIAPAS, MEXICO

Fred G. Thompson

Florida State Museum

University of Florida

Gainesville," Florida 32611

The genus Epirobia consists of small slender

urocoptoid land snails that are found character-

istically on limestone in wetter areas of eastern

Mexico and northern Guatemala. The descrip-

tion of two new forms is presented so that they

may be included in a report on the land mol-

lusks of Chiapas by Allyn G. Smith. I wish to

express my appreciation to him for allowing

me to examine pertinent material in the collec-

tions of the California Academy of Sciences

(CAS). Other material cited in this paper is

deposited in the Florida State Museum, Uni-

versity of Florida (UF) and the Delaware Mu-

seum of Natural History.

Epirobia swiftiana alternans new subspecies

Fig. 1, c and d. Fig. 2, a.

Shell. — Elongate fusiform-turreted, thin, tran-

slucent. Spire complete; upper % of spire

gradually tapering to the third or fourth from

last whorl; shell 0.19-0.21 times as wide as

long; narrowly umbilicated. Color light brown

with alternating patches of white ribs. Whorls

19.5-20.5 (20.2 in holotype). Suture moderately

impressed, not crenulate. Embryonic whorls 2.9-

42 THE NAimmS

Jamiarv .'^O. 197B

Vol. 90 (1)

FIG. 1. Epirobia lurida new species, a, hnlntype 16.S mm., b, paratope. Epirobia swiftiana alternans «<»?/' subspecies, c,

hiitiit ijpr. d, pamti/pe.

3.4 (3.1 in holotype), relatively weakly arched,

smooth and nearly equal in size. Following

whorls nearly uniformly rounded at periphery,

more so near sutures. Neck of last whorl round-

ed, below, without any indication of a basal

keel. Whorls sculptured with clusters of narrow,

graceful, sigmoid white ribs. Clusters separated

from each other by nearly equally wide smooth

zones. About 3-10 ribs per cluster and about 5-6

clusters per whorl on lower whorls. Ribs about

half as wide as their intervals. Rib intervals

and smooth zones light brown. Aperture free

from preceding whorl, projecting forward and

offset laterally. Aperture broadly ovate, slightly

higher than wide, slightly oblique; about 0.60-

0.69 times the width of the last whorl.

Peristome white, moderately reflected,

narrowest along posterior comer; widest along

rolumellar margin. Axis hollow and about '4

diameter of whorls. Axis weakly concave within

each whorl; sculptured with weak, slightly

oblique vertical ribs bearing small spines and

nodes that are irregularly sized and spaced.

Measurements in mm of mature specimens

are as follows (measurements of the holotype

are in parentheses): length, 13.0-14.2 (13.8; width,

2.6-2.8 (2.6); aperture height, 1.7-1.85 (1.8);

aperture width, 1.6-1.8 (1.7). (14 specimens

measured).

Type hcality — Chiapas, 4.5 miles north of

Jitotol, 5400 feet altitude HOLOTYPE: UF

22451; collected 6 July, 1965 by Fred G. Thomp-

son. PARATYPES: UF 22452 (12); and Dela-

ware Mus. Nat. Hist. 102474 (1) same data

as the holotype. The type series was found in a

thick cluster of moss growing on the side of a

limestone ledge along a ravine. The area con-

sisted of semi-wet mountain broadleaf forest

which had been partially cut over.

Remarks — This subspecies differs from E S.

suriftiana (Crosse) by being shorter, having

fewer whorls, more embryonic whorls and

having a rounded base on the last whorl. E s.

smftiana is about 18 mm long, has 21 whorls,

including 1.5 embryonic whorls, and the last

whorl is obsoletely subangulate below. The

nominate subspecies is known only from the

type specimen, which comes from an unspecified

Viil. 90 (1)

January 30, 1976

THE NAUTILUS 43

locality (Crosse, 1863; 388-389. 1867: 200-201,

pl.s. fig. 5. Fischer and Crosse, 1878: 407). It

I)r(>bably occurs in Chiapas, as does E. .s. al-

Epirobia lurida >iew species

Fig. 1, a and b. Fig. 2, b.

S/ie// — Elongate-t arreted, very slender, 0.15-

0.17 times as wide as long. Spire complete,

uniformly increasing in diameter through the

fourth from last whorl. Moderately thin, only

slightly transparent when alive. Umbilicus

narrowly perforate, visible from oblique view.

Color light yellowish-gray, lusterless, dull, in-

terior of aperture white. Whorls 22.5-25.0 (23.2

in holotype). Suture deeply impressed. Em-

bryonic whorls 3.0-3.2 (3.1 in holotype), smooth,

strongly arched peripherally wath a deeply im-

pressed suture; nearly equal in size. Following

whorls gradually increasing in diameter through

about the eighteenth whorl; sculptured with

regularly spaced ribs. Ribs on lower whorls are

about twice as high as wide, slope obliquely for-

ward and are about one fourth as wdde as their

intervals. There are 35-49 ribs on penultimate

whorls (38 in holotype). Ribs strongly arched in

a reverse sigmoid curve. Periphery of postem-

bryonic whorls strongly rounded on upper spire.

Lower whorls flat sided and almost scalariform.

The flattened periphery is slightly oblique to

the axis of the shell. Base of last whorl round -

FIG. 2. Camera lucida drawings of the coiumeUar striic-

ture in the penultimate whcrrls of a, Epirobia swiftiana

alternans new subspecies and, b, Epirobia lurida new

species.

ed, without indication of a bisal keel. Aper-

ture free from preceding whorl, offset laterally

and extended forward by about V2 diameter of

shell. Aperture broadly auriculate in shape;

about 0.73-0.80 times width of shell; posterior

corner narrowly rounded. Peristome moderately

reflected; narrowest around posterior comer;

widest along baso-columellar margin. Outer lip

sigmoid in lateral profile, corresponding in

outline to curvature of ribs on previous whorl.

Plane of aperture slightly oblique to axis of

shell. A.xis hollow, about Vs diameter of whorls,

nearly straight, slightly twisted in lower whorls.

Axis uniformly wide or slightly concave within

each whorl; sculptured with small granular

spines which tend to form oblique series.

Measurements in mm of mature specimens

are as follows (measurements of the holotype

are in parentheses); length, 15.5-18.3 (16.3); width,

2.4-2.7 (2.6); aperture height, 1.8-2.1 (2.0); aper-

ture width, 1.8-2.1 (1.95).

Pallial organs — The pallial cavity is about 4

whorls long. The kidney is about V4 whorl long,

narrow, reniform sigmurethrous. The secondary

ureter is about equal in diameter to the in-

testine and is tightly bound to the latter. The

heart is about '4 the length of the kidney. The

aorta lies along the ventral margin of the lung

and is weakly branched throughout most of its

length. It divides into 5-6 small arterioles just

behind the mantle collar.

Trophic structures — J avf solid, arcurate.

Salivary glands plumiform, appressed against

the side of the esophagus; short, about half the

length of the pharynx. Salivary ducts about half

the length of the glands. Radular sac short,

coiled in a loop against posterior end of

pharynx. Radular formula 17-1-17 with the

teeth lying in broadly accurate transverse rows

about 390 /^ wide (Fig. 3, b-c). The central tooth

is hexagonal in shape and has a large mesocone

and a small ectocone on each side. The central

is about 19 /i high and 14 ^ wide. The tran-

sition from the laterals to the marginals occurs

at the fifth through seventh rows. The laterals

each bear a large blunt mesocone and a small

ectocone. The mesocone of the seventh tooth and

subsequent marginals is pointed where both the

mesocone and the ectocone are bicuspid.

Muscular system — CoiumeUar retractor long,

44 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

B . i°" .

FIG. 3. Epirobia lurida new species, a, reproductive system exclusive nf the yanml. b, nuhiln. c, (lidiinimntic rieir nf n trans-

verse rn>r of the mdiiln shnviyy the respecfire lyisitiims <if the teeth illu.^lratcd in b.

extending seven whorls into spire; dividing at

the third whorl to give rise to the pedal retrac-

tor basally, the pharyngeal retractor dorsally

and the right and left ocular retractors

laterally. The ocular retractors respectively give

rise distally to the right and left labial retrac-

tors. The pharyngeal retractor divides into four

narrow bands at base of pharynx. Two insert

laterally and two insert basally.

Reproductive System (Fig. 3, a). — The genital

atrium is medium in length, moderately stocky

and opens behind and below the right ocular

tentacle. The right ocular retractor muscle

passes through the penioviducal angle. The

penis is long and slender, being about twice the

length of atrium and has four longitudinal

fleshy folds internally, one of which is larger

than the others along the upper third of the

penis. There is not verge. The apex of the penis

bears a long slender compressed caecum which

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 45

is about twice the length of the penis. The

penis retractor muscle is long and slender. It

originates on the inner wall of the lung about

Vi whorl above the penis and inserts on the

distal end of caecum. The vas deferens is

relatively stocky above the penis and is weakly

enlarged as an epiphallis for a distance about

equal to the length of the penis. It enters the

wall of the free oviduct below the prostate and

oviduct. The spermathecal duct enters the free

oviduct to form a short vagina immediately

above the atrium. The base of the duct is

enlarged into a thick-walled muscular bulb. The

duct is branched distally. The spermatheca lies

appressed against the outer base of the

albumen gland. The spermathecal appendix lies

along the columellar side of the oviduct and

albumen gland. The free oviduct is about 1.5

times the length of the penis, is strongly con-

voluted and becomes moderately wide a little

above the insertion of the spermathecal duct.

The albumen gland lies about four whorls above

the genital atrium and is strongly creased on

its outer surface by the intestine. A talon and

a carrefour are absent.

Tifpe locality — Chiapas, 15.8 miles northwest

of Ocozocoautla on road to Mai Paso, 2700 feet

altitude. HOLOTYPE; UP 22449; collected 20

July, 1965 by Fred G. Thompson. PARATYPES

UP 22450 (116): Delaware Mus. Nat. Hist.

102475 (5); same data as the holotypes; UP

22448 (4), CAS 55555 (30); topotypes. collected 6

October, 1974 by Dennis E. Breedlove. The type

locality is an area covered by a heavy quasi -

rainforest on low, rolling limestone hills. Live

snails were found only on damp moss-covered

limestone boulders.

Remarks — E. lurida is distinguished from

other species of the genus by its flat sided

whorls, its high sigmoid riblets and its slender

straightsided axis with granular spines arranged

in irregular oblique rows. It is similar to E.

pulinigyra (Pfeiffer) from Veracruz in general

aspects of size, shape and whorl count, but the

latter species has evenly rounded whorls, the

riblets are fine threadlike striae and the axis is

convex within each whorl with the rough

granular sculpture confined primarily to the

center of the convexity. E. polygyrella (von

Martens) from Alta Verapaz has shorter, more

strongly rounded whorls, the aperture is nearly

rotund, the axis has slender retracted riblets

that lack granular sculpture and the shell is

smaller.

DISCUSSION

There are seven species and two subspecies of

Epimhia known. Three are recorded from

Veracruz, four from Chiapas, one from Alta

Verapaz, and one was described without any

locality. For a review of the genus see Pilsbry,

1903: 59-66.

Three other snails that were described as

species of Epirobia from northeastern Mexico

are now placed elsewhere. E. coahuilensis Bar-

tsch, 1906, has been referred to Coelostemrna

(ApeHaxis) by Thompson (1971: 301) and E

(Propilsbrya) nelsoni Bartsch, 1906 was elevated

to generic rank as Propilsbrya nelsoni by

Pilsbry (1953: 136). The status of E. (Gyrodon)

mirabilis Pilsbry, 1903a is problematic. It is

known only from a single immature shell, and

its generic status is questionable. Certainly

Gyrodon is very different from Epirobia s.s.

Epirobia (s.s.) contains two species groups.

One group, consisting of E. berendti (Pfeiffer),

E. b. albida (Fischer and Crosse) and E. gassiest

(Pfeiffer), includes species that have relatively

short obese shells. The second group, consisting

of E. s. swijiiana (Crosse), E. s. altemans n.

ssp., E. apiostoma (Pfeiffer), E. polygyra (Pfeif-

fer), E. polygyrella (v. Martens) and E. lurida

n. sp., includes species that are relatively long

and slender.

Previously two taxa were recorded from

Chiapas, E. b. albida and E. gassiesi. Neither of

these is known from a more exact locality than

the state of Chiapas and both belong to a differ-

ent species group than do the two new forms.

E. s. altemans and E. lurida establish the first

exact records of the genus within Chiapas.

They come from an area forming more nearly a

geographic continuum from Veracruz to Alta

Verapaz for the species group to which they

belong.

Epirobia is a member of the family

Eucalodiidae, subfamily Holospirinae because of

its non-decollate shell, solid jaw, trimorphic

radular teeth, the presence of an appendix on

the spermathecal duct, the absence of a verge

46 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

within the penis and the absence of a talon and

a carrefour. It is unique among the eucalodiid

genera for which the anatomy is known by

having a long, slender, compressed penial

caecum, a large muscular bulbous base on the

spermathecal duct, the vas deferens entering the

oviduct wall below the prostrate, and the

mesocones and ectocones of the central and

lateral teeth having large rounded cusps. Un-

fortunately anatomical information is not

available on most other genera within the

Holospirinae, and comparisons are not possible

at present.

The above anatomical characterization of

Epirabia is based exclusively on E. lurida

because of a lack of data on other species.

Strebel and Pfeffer (1880) describe and

illustrate portions of the reproductive system

and the radula recovered from a dried E

apiostoma (Pfeiffer). Pilsbry (1903: 60) expresses

doubt about the identity of the radula. Strebel

and Pfeiffers' description of the reproductive

system are very different from that of E.

lurida, to the extent that doubt about the iden-

tity of their material is even more warranted,

and comparisons involving E. apiostoma cannot

be made at this time. It is possible that

Ejrirobia is a compound genus based on shell

convergences.

LITERATURE CITED

Bartsch. P. 1906. The urocoptid mollusks from the mainland

of America in the collection of the United States Na-

tional Museum. Proc. U.S. Nat. Mus. 31: 109-160; pis.

3-5.

Crosse. H. 1863. Diagnoses d'especes nouvelles. Journal de

Conehylidogie 11: 388-389.

1867. Descriptions d'especes nouvelles. Journal de Con-

chyliolugie 15: 195-203; pi. 4, figs. 1, 4; pi. 5. figs. 2-5.

Fischer, P. and H. Crosse 1878. Miision Scientifique an

Mexiqve et dans L'Amerique Centrale. Moliasques terres-

tres et fluviatiUs. Paris. 1: 1-702; pis. 1-20.

Pilsbr>'. H. A. 1903. Mamml of Conchology: Ser. 2, 15:

1-323; pis. 1-65 1903a. Mexican land and freshwater mol-

lusks. Proc. Acad. Nat. Sci. Phila 55: 761-792; pis. 47-54.

19.53. Inland Moilusca of northern Mexico. II. Proc. Acad.

Nat. Sei. Phila. 105 133-167; pis. 3-10.

Strebel. H. and G. Pfeffer 1880. Beitrag ^ir Kenntniss der

Fauna Mexikanischer Land — urd Susswasser — Conchy-

lien. IV. Hamburg. 1-112; pis. 1-15.

Thompson. F. G. 1971. Some Mexican land Snails of the

genera Cnelostemma and Metastomn (Urocoptidae). B)dl.

Flo. State Mus. 15: 267-302.

A NEW SPECIES OF CALLISTOCHITON IN THE CARIBBEAN

Antonio J. Ferreira'

2060 Clarmar Way

San Jose, California 95128

ABSTRACT

A new frpecies of chiton. Callistochiton portobelensis Ferremi, .sp. nov.. k de-

scribed and figured. Found at Portobelo. Panama (type locality) and off Key

West, Florida, it closely resembles C. elenensis (Sowerby) fi-om the eastern Pa-

cific.

In the Caribbean, the genus Callistochiton

(Carpenter in Dall, 1879) has been thought to

be represented by a single species,

Callistochiton shuttleworthianus Pilsbry, 1893.

In February 1975, while on a collecting trip to

the Caribbean shores of Panama, I came across

several specimens of what subsequent investi-

gation proved to be an undescribed species of

Callistochiton.

Research Associate, California Academy of Sciences.

Class Polyplacophora de Blainville, 1816

Subclass Neoloricata Bergenhayn, 1955

Family Callistoplacidae Pilsbry, 1893

Callistochiton portobelensis new species

Figs. 1-6

Diagno.'iis — Chiton small, less than 1 cm

long, greenish cream color. Anterior valve with

about 12 subdued radial ribs; posterior valve

with none or a few obsolete radial ribs. Mucro

47 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

FIG. 1. Callistochiton portobelensis Ferreira. new speciea.

Paratope. Portnbelo. Panama. 6.7 mm in length.

FIG. 2. Side I'iew of lateral areas of parati/pe.

slightly anterior. Lateral areas bicostate, with

minute tubercles along the posterior margins.

Central areas somewhat diagonally ribbed, and

latticed. Jugal area smooth. Girdle scales cylin-

droid, small, weakly imbricated, outer surface

oval and minutely granulose.

Desmptian of the h-olotype — The specimen,

dried but fully extended, measures (including

girdle) 6.7 mm in length, 3.6 mm in width, and

L2 mm in height. Width to length ratio =

0.53. Jugal angle about 96°. Tegmentum of a

rather uniform greenish cream color, with oc-

casional small darker green blotches peppering

the shell in a random manner; the general sur-

face is microgranular throughout. Anterior

valve shows 12 low-profile radial ribs, better

defined towards the periphery where they seem

more like undulations than ribs on the tegmen-

tum. Posterior valve shows a well defined but

not conspicuous mucro, slightly anterior; the

post-mucro area is moderately concave, with

only the faintest indication of radial ribbing.

Intermediate valves have moderately elevated

lateral areas bearing 2 broad, slightly granose,

low ribs which show no tendency to split; the

space between the two radial ribs is well

defined but shallow. The posterior of the two

ribs in the lateral areas tends to have a few

minute, almost obsolete tubercles along its

sutural edge. The central areas have

longitudinal riblets, about 10 per side,

diagonally disposed by diverging forward as a

whole at about a 20° angle from the midline;

there is no "wedge" figure on valve ii (Ferreira,

1974: 163). The longitudinal riblets are about as

wide as the space that separates them, and

united by some discrete latticing. The central

FIG. 3. Callistochiton ixirtobelensis Ferreira. new species.

Holotifpe. SEM microphotographs (courtesy of Hans Bertsrh)

if girdle scales. Approx. iOOX.

FIG. 4. Girdle scale of holoti/pe. Approx. 500X.

48 THE NAUTILUS

January 30, 1976

Vol. 9(1 (1)

FIG. 5. Detail of girdle scale of hololt/pe. Approx. 1500X.

5».><.

loo A

FIG. 6. Callistochiton portobelensis Ferreira, new species.

Holotype. Radula (Camera lucida drawing).

sculpture becomes obsolete towards the jugal

area, which is mostly smooth. The ar-

ticulamentum is white but, by transparency,

shows some occasional small dark blotches. In-

sertion teeth are straight edged except at the

corners where they tend to be a bit thicker and

rounded. There is no clear cut festooning or

scalloping in any of the teeth. Slit formula 11-

1-9. The slits correspond well with the tegmen-

tal undulations or ribs. Sutural laminae are

sharp, semioval, short, and continue with no

visible demarcation or notch with the sinusal

lamina. Sinus is relatively shallow. Eaves

short and solid. The callus inside valve viii is

suffused with dark-brown pigmentation. The

girdle has a uniform width of 0.5 mm; it is the

same color as the tegmentum but softly banded

with green. The scales measure about 80fj in

length. They are weakly imbricated, standing

close together like cobblestones on a pavement.

Somewhat cylindrical in shape, their sides (jux-

taposed, and therefore hardly visible in the un-

disturbed girdle) are neatly ribbed vertically,

while its outer (distal) surface, oval in outline,

and slightly convex is minutely pustulose. (Figs.

3, 4, 5). The radula measures about 1.6 mm in

length, and has 44 rows of teeth. The median plate

(tooth) is wider anteriorly (30/i) with a very

thin blade, markedly narrowed medially (12^^),

and again somewhat dilated posteriorly to ter-

minate rapidly in a blunt point. The in-

termediate (first lateral) plate has a small

superiorly recurved uncinated growth at the

outer-anterior comer. The uncinate (second

lateral, major lateral) plate has a long and

thick (25ji X 8fi) tubercle inwardly directed,

, and a unicuspid blade, about 52fi long by 25ji

wide, with a small posterior notch (Fig. 6).

Type material — Holotype (disarticulated

valves, excised fragments of the girdle, and

mounted radula) and a paratype (Figs. 1, 2),

are deposited with the California Academy of

Sciences, Department of Invertebrate Zoology

(CASIZ Type Series 679 and 680; CASIZ Type

. Slide Series 493 and 494). Color slides of some

paratypes are deposited with the California

Academy of Sciences, Department of Zoology

(CASIZ Color Slide Series nos. 3259, 3260, and

3261).

The paratypes vary in size from 5.1 mm to

6.9 mm in length. They all have the same

general coloration (with one exception— a

uniform brick-red specimen, with faint

creamish banding of the girdle), and some

irregular, small, greenish blotches. Paratypes

deposited with the Los Angeles County Museum

of Natural History, United States National

Museum of Natural History (USNM no. 710720),

Academy of Natural Sciences of Philadelphia,

and in my own private collection.

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 49

Type locality — 5 km west of Portobelo

(latitude 9° 30' N; longitude 79° 42' W),

Panama. The specimens were all collected on

February 15, 1975, by myself, in about 1 to 10

feet of water, under rocks or fragments of old

coral resting on sand. They came from two

collecting stations (AJF 222, and 223), about 1

km west of Portobelo (1 specimen, 5.5 mm

long), and 5 km west of Portobelo (10

specimens, including the here designated

holotype), respectively. The species is called por-

tdbelenm in reference to its type locality, Por-

tobelo.

Fiirther distribution — Another specimen of

Callistochiton porta belensis was found by the

author on April 28, 1975, while diving from

aboard the R/V Cord Reef with the Steinhart

Divers of the California Academy of Sciences,

in 5 m of water by the Northwest Channel

(latitude 24° 30' N; longitude 81° 54' W), off

Key West, Florida. The specimen measures 9.0

mm in length. This finding extends the known

range of C. portobelensis some 1,000 miles north-

ward.

Discussion — Callistochiton portobelensis bears

little resemblance to C. shuttleworthiamis, the

only member of the genus Callistochiton hither-

to known in the Caribbean (KAAS, 1972). In-

stead, in size, color, general shape, sculpture of

the tegmentum, and girdle scales, C por-

tobelensis is remarkably similar to

Callistochiton elenensis (Sowerby, 1832) from

the tropical eastern Pacific. Compared with ran-

domly selected specimens from several lots of C.

elenensis in my collection, C portobelensis was

found to differ by 1) its smaller size, 2) a much

more subdued sculpturing of the valves, par-

ticularly of the radial ribs in valves i and viii,

3) a more rounded and smoother jugal area, 4)

no "upswept" valves (see Thorpe in Keen,

1971:875), and 5) thicker longitudinal riblets,

separated by narrower interspaces.

Still, the affinities between C. portobelensis

and C. elenensis are so close as to make them

sibling species. Likely, they evolved from the

same parent population and became

geographically isolated by the emergence of the

isthmus of Panama in the Pliocene.

ACKNOWLEDGEMENTS

I wish to express my appreciation to Hans

Bertsch of the Donner Laboratory, University of

California, Berkeley, for the SEM microphoto-

graphs; and to the Steinhart Divers of the

California Academy of Sciences, and to Beta

Research Oceanographic Laboratories, for their

assistance in several phases of this work. I

wish further to give my thanks to Allyn G.

Smith of the Department of Geology of the

California Academy of Sciences for his valuable

critical comments of the manuscript.

LITERATURE CITED

Ferreira, Antonio J. 1974. The genus Lepidozona in the

Panamie Province, with the description of two new spe-

cies. The Veliger. 17(2): 162-180, 6 pits. Berkeley. Cali-

fornia. October 1.

Kaas, P. 1972. Polyplacophora of the Caribbean Region.

Studies on the Fauna of Curacao and other Caribbean

Islands, vol. 41. no. 137. 162 pp.. 247 text figs., 9 pits.

Martinus Nijhoff. TTie Hague. July.

Keen, A. Myra 1971. Sea Shells of Tropical West America:,

Marine Mollusks from Baja California to Peru. 2nd ed.

Stanford University Press, xiv -I- 1064 pp., ca. 4000 figs.,

22 color pis. September 1.

A NEW FOSSIL ASHMUNELLA (PULMONATA: POLYGYRIDAE) FROM THE

GUADALUPE MOUNTAINS NATIONAL PARK, TEXAS

Artie L. Metcalf

Department of Biological Sciences

University of Texas at El Paso

El Paso, Texas 79968

and

Richard W. FuUington

Dallas Museum of Natural History

Fair Park Station

Dallas, Texas 75226

ABSTRACT

A new species of fossil polygynd hnid snail. Ashmunella nana, is described.

The .species is known only from depo.sits of Pleistocene age in the southern

50 THE NAUTILUS

January 30. 1976

Vol. 90 (1)

Guadalupe Mountains, Culberson County, Texas. An associated molluscan fauna

in these deposits is recorded and remarks are made concerning Oreohelix

socorroensis Pilsbi-y.

INTRODUCTION

Pine Spring Canyon in the southern

Guadalupe Mountains, Culberson County, Texas,

has received considerable attention

malacologically. It is the type locality of

Holospira montivaga breviara Pilsbry, 1946, of

Holospira pityis Pilsbry and Cheatum, 1951, and

of Ashmunella kochi amblya Pilsbry, 1940. The

canyon is now in a central position in the

Guadalupe Mountains National Park.

Exposed in walls of Pine Spring Arroyo are

thick alluvial deposits that contain fossil

mollusks. On slopes of the canyon above the

arroyo there are fossiliferous colluvial deposits.

At the locality reported here, there are two

strata of nibbly oolluvium (to be referred to,

hereafter, as "lower rubble" and "upper rub-

ble") separated by reddish silt, containing scat-

tered, subrounded stones. The rubble is

predominantly of small, sharply angular

limestone fragments of the type interpreted by

Galloway (1970 : 245), in the Sacramento Mts.

(120 km to the northwest, in New Mexico), to

be periglacial deposits of frost rubble. It seems

probable that the upper rubble was deposited

during the latest Wisconsinan Glaciation. The

reddish deposits probably represent a paleosol

appertaining to an interstade or interglaciation

and the lower rubble seemingly represents

either an earlier Wisconsinan or still earlier

time when periglacial conditions existed in the

mountains.

The molluscan fauna found in the lower rub-

ble comprises, among others listed below, Ash-

munella rhyssa (Dall) and a new species,

described below. Neither species is known to

live in the Guadalupe Mts. at present and the

latter seems to be an extinct species. A. r.

rhyssa still flourishes in the Sacramento Moun-

tains. In the upper rubble a different Ash-

munella, A. kochi amblya Pilsbry, occurs. This

species presently inhabits Pine Spring Canyon

and other parts of the southern Guadalupe Mts.

The sequence suggests that the two former

species of Ashmunella became extinct in the

Guadalupe Mts. between the times of deposition

of the lower and upper rubbles and that A.

kochi amblya appeared in the mountains during

the time of the latest glaciation. [Vagvolgyi

(1974 : 143) suggested that the subspecies amblya

might better be synonymized with the nominal

subspecies.]

Ashmunella nana new species

Figs. 1-3

Description of Holotype: Shell small (for

genus), moderately depressed, 10.6 mm in

diameter, 5.0 mm high; body whorl rounded

peripherally and descending only slightly; um-

bilicus round, deep, contained 5.4 times in

diameter; aperture obliquely oriented, 3.2 mm

in oblique distance between inner comers of

lip; aperture bearing four denticles; parietal

FIGS. 1. 2. Hi)li>t!/pe of Ashmunella nana new upecies (10.6

mm diameter). FIG. 3. Aix'rtiiml view nf paratype of A.

nana.

Vol. 9() (1)

January 30, 1976

THE NAUTILUS 51

tooth oblique, simple, 1.7 mm long, .4 mm high;

palatal tooth rectangular, 1.1 mm long and .5

mm high, basal lip with two teeth, both com-

pressed, 1.0 mm apart, upper tooth rising .6

mm and lower tooth rising .2 mm above inner

rim of lip; lip slightly expanded and recurved,

grooved behind; first 1''4 whorls smooth, except

for minute pits; succeeding whorls finely

wrinkle-striate to last half of body whorl, which

bears ca. 26 low but distinct ribs, better

developed dorsally and progressively thicker

distally; total number of whorls, 4.75.

Etymology: nowa =dwarf (L., fem., subst.).

Variation: For fifty paratypes from the type

locality, the following measurements (mm) and

proportions were obtained (mean outside paren-

thesis; range inside parenthesis); Diameter:

10.07(9.1-11.2); Height: 4.53(4.0-5.2);

Diameter/Height: 2.21(1.98-2.47); Width of Um-

bilicus: 1.96(1.4-2.5); Diameter /Width of Um-

bilicus: 5.17(4.32-6.50); Length of Parietal Tooth:

1.51(1.2-1.8); Length of Palatal Tooth: 1.24(0.7-

1.5); Number of Whorls: 4.86(4.6-5.25). All

specimens' observed had four denticles (except

where exfoliated), which showed only minor

variation in shape and size. There was variation

in degree of ribbing, ranging from few ribs to

specimens in which most or all of the body

whorl bore ribs dorsally and peripherally.

Measurements of four specimens taken ca. 60 m

southeast of the type locality (see below) fell

within the limits enumerated above.

Comparisons: A. nana is among the smallest

of Ashmunellas. The only members of the genus

reported to be as small are A. proxima harveyl

Pilsbry (Pilsbry, 1940 : 959) with a specimen

reported as being 10.3 mm in diameter and 5.0

mm high and A. intricata Pilsbry (Pilsbry,

1948 : 203) with specimens recorded as 9.6 and

10.6 mm in diameter and 4.7 and 4.8 mm high.

A. nana seems to bear little resemblance,

conchologically, to any known species of Ash-

munella, living or fossil, from the region east of

the Rio Grande Valley. In general shape and in

number and arrangement of denticles it resem-

bles the A. proxima Pilsbry complex of the

Chiricahua Mts., Arizona. However, A. nana is

much less tightly whorled, less angular

peripherally and is much more ribbed than

members of the proxima complex. A close

relationship with this distant group seems

unlikely.

In contrast to A. nana, in regard to size, is

A. kochi amblya, which may exceed diameters

of 20 mm. Thus, one of the largest and one of

the smallest of Ashmunellas have inhabited

Pine Spring Canyon. A. nana seems to bear lit-

tle relationship either to A. kochi amblya or to

the other living species of the Guadalupe Mts.,

A. edithae Pilsbry and Cheatum and A.

carlsbaderms Pilsbry. The wide, shallow um-

bilici of the latter three species are in marked

contrast to the narrow, deep umbilicus of A. nana.

Type Locality: Texas, Culberson Co.,

Guadalupe Mts., Pine Spring (Canyon, 3.2 km (2

mi.) WNW of village of Pine Springs. 104° 50'

45" W Long, 31° 54' N Lat; 1912 m (6270 ft.)

elevation. Deposits are exposed in banks of a

small arroyo of high gradient, tributary, from

the west, to the main arroyo of the canyon.

Deposits occur ca. 30 m west (on east-facing

slope) and up-slope from a right-angle bend in

the main arroyo (changing from west to north,

up-canyon). This sharp bend is .65 km (.4 mi.)

south of the "H" in "Devil's Hall" (U.S.G.S.

Guadalupe Peak, Texas, 15 min. topographic

quadrangle, 1933).

Types: Holotype, Acad. Nat. Sci., Philadelphia

338703; Paratypes: ANSP 338704; Dallas

Museum Nat. Hist. 4400; The Delaware

Museum Nat. Hist. 100700; University of

Arizona 17382; Museum of Arid Land Biol., U.T.

El Paso 4165, 4170.

ASSOCLVTED FAUNA

In association with A. nana and A. r. rhyssa,

the following species of snails have been taken

in the lower rubble: Cochlicopa lubrica (Miiller),

Gastrocopta pilsbryana (Sterki), Pupilla

sonorana (Sterki), Pupilla blandii Morse,

Vallonia gracilicosta Reinhardt, Vcdlonia per-

spectiva Sterki, a succineid, Holospira nwn-

tivaga breviara Pilsbry, Discus cronkhitei

(Newcomb), Helicodiscvs eigenmanni Pilsbry,

Retinella indentata (Say), Hawaiia minuscula

(Binney), Zonitoides arboreus (Say), Striatura

meridionalis (Pilsbry and Ferriss), Vitrina

pellucida alaskana Dall, Oreohelix socorroensis

Pilsbry and Humboldtiana ultima Pilsbry.

Recent collecting by Fullington shows that all

52 THE NAUTILUS

January 30. 1976

Vol. 90 (1)

these species except probably the Oreohelix still

occur in the Guadalupe Mts. but several species

now occur only at higher elevations.

Oreohelix socorroensis was taken in both the

lower and upper rubble. It also occurs in

alluvium along Pine Spring Canyon Arroyo.

Probably specimens of 0. yavapai compactula

G)ckerell reported by King (1948 : 145) were of

this species. 0. socorroensis has been found, as

a fossil, in the Sacramento and San Andres

Mts., New Mexico, and in the FYanklin, Hueco

and Guadalupe Mts., Texas. It still lives in the

Gallinas Mts. in central New Mexico. It is

surely allied to the 0. yavapai Pilsbry complex

of northern New Mexico and Arizona, especially

to 0. yampai neomexicana Pilsbry. However,

elucidation of relationships probably would in-

volve a taxonomic revision of the entire yavapai

group, a task not undertaken lightly.

LITERATURE CITED

Gallaway. R. W. 1970. The full-glacial climate in the south-

western United States. Ami. Assoc. Amer. Geogr. 60:

24.5-2.56.

King. P. B. 1948. Geology of the southern Guadalupe Moun-

tains. Texas. U.S. (kol. Sun: Prof. Pap. 215: 1-183.

Pilsbry, H. A. 1940. Land Mollusca of North America

(North of Mexico). Acad. Nat. Sci. Philadelphia Monogr.

1(2): vi + .575-994.

Pilsbr>'. H. A. 1948. Inland mollusks of northern Mexico. -

I. the genera Humlxjldtiana. S(jnorella. Oreohelix and

Ashmunella. Proc. Acad. Nat. Sci Philadelphia 100:

185-203.

Vagvolgyi. J. 1974. Eight new Ash man el hu-; from the S(juth-

western United States (Pulmonata: Polygjridae). Proc.

Biol. Soe. Washington 87: 139-166.

TENTACLE-BRANCHING IN THE PERIWINKLE, LITTORINA LITTOREA

Richard G. Woodbridge, III

Ekjx 111, Princeton .Junction,

New Jersey 08550

Abnormalities in mollusks have been noted

by many observers and are the subject of a

treatise by P. Pelseneer (1920). In gastropods,

supplementary or multiple tentacles have been

noted in several cases, but, as Pelseneer noted,

they are moi:e common on one side than the

other. Branching has been particularly noted in

Littorina. Pelseneer's own observations may be

summarized as follows:

Jeffreys (1862) noted a specimen of L. littorea

which had two tentacles branched. He also com-

mented in reference to a supplementary ten-

tacle observed in a specimen of L. ohtusata.

that the extra tentacle is not far removed from

the normal one.

Hanko (1912) in a paper delineated the

varieties of tentacle-branching which have been

observed in Nasmrius mutahilis (L).

Crabb (1927) studied forked tentacles in the

pond snails Physa gyrina and Lymnaea

stagnaJis appressa.

Wong and Wagner (1956) reported on the ef-

fect of ultraviolet light on the tentacles (among

other things) of Oncomelania nosophora and 0.

quadrasi. Exposure to ultraviolet light causes

abuornial growth structures in many individuals

of these species. However, abnormal tentacles

tended to be lost over a period of time.

Davis, Moose & Williams (1965) described a

specimen of a hybrid Oneomelauia with ten-

tacle abnormalities and stated "It is known

that the tentacles of Oneomelania are prone to

abnormal branching." The authors suggested

that inheritance might be involved in tentacle

branching.

Richards (1969) in an important paper

showed that inheritance appears to play a part

in tentacle branching of the freshwater

pulmonale mollusk Biomphalaria glabrata.

While observing 50 living periwinkles which

had been selected for experimental purpose

from near the low tide mark of the intertidal

region of Northwest Harbor, Deer Isle, Maine,

the summer of 1971, the writer noticed one

specimen with a bifurcated tentacle (fig. 1).

Subsequently, four collections of periwinkles,

consisting of 1,026 living specimens were

examined with the following results:

Vol. 9<) (1)

January 30, 1976

THE NAUTILUS 53

TABLE 1. Tentacle-branching in the Littirrina

Species

L littorea

L )itdis (saxatilis)

L. nbtiixata

TABLE 2.

Date

(1971)

July 27

July 2!-)

July -St) (lot 1.)

July 30 (lot 2.)

Ntimber nf

Indi I'idualK

Nuted

1

5

3

Number Obseiiied

100

303

318

305

1,026

Tentacle

Left Right

Number with

Forked Tentacles

2

4

3

1

10

The periwinkles with the forked tentacles

were subsequently brought back to the writer's

laboratory aquariums in Princeton, New Jersey,

for continuing observation. In contrast to the

findings of Wong and Wagner (1956) on the

ultraviolet light induced tentacle growth ab-

normalities in Oncomelania. the branched ten-

tacles of these periwinkles appeared permanent

and stable, certainly as "normal" as normal

tentacles, for the period of over eleven months

during which they were under observation.

Each fork of a tentacle shows independent

activity. Both forks in the tentacle shown in

drawing 1 moved separately and conducted in-

dependent searching movements. This was also

true in specimen 8, which was surprisingly

prehensile in appearance and movement.

Small forks in numbers 4, 5 and 6 showed

more independence of motion than the smaller

forks of numbers 2 and 7.

Microscopic examination of numbers 1 and 8

showed no difference internally or externally in

the organization of the forks. Tentacle forks are

organized tissue and certainly not "cancer-like."

Number 10 was the only case found with

multiple forking.

A further analysis of lot 2 collected on July

30 containing 305 specimens gave the following

results of the 18 abnormal specimens (5.9%):

TABLE 3.

Tentacle Abnormality

Missing

Short

Bent

Forked

Totals

Left Tentacle

1

12

0

_0

1.3

Right Tentacle

1

1

2

J_

5

FIGS. 1-10. Ahnnrmnl branching in the tentacles of Litto-

rina littorea (Linn').

No periwinkles were observed in which both

tentacles appeared to be abnormal.

It should be noted that forking is not restricted

to the phylum Mollusca but occurs in other in-

stances involving the regeneration of structures.

In the case of lizards which cast off their tails to

escape being eaten, regeneration occurs in such a

manner as to give a forked tail.

It is possible that the bites of very small fish

in some instances do not remove but only in-

jure the tentacles of periwinkles in such a man-

ner that regeneration results in similar forking.

LITERATURE CITED

Crabb, E. D. 1927. Genetic experiments with pond snails

Lymnaea and Physa. Amer. Naturalist 61: 54-67.

Davis, G. M., Moose, J. W. and Williams, J. E. 1965. Abnor-

mal development in a hybrid Oncomelania (Gastropoda;

Hvdrobiidae). Malacotogm 2: 209-217.

Duprey. cf. Jeffreys. 1883. Proc. Zool. Soc. London, p. 122.

Ref. in Pelseneer.

Hanko, B. 1912. Uber Missbildungen bei Nassarius mutabilis

(L.). Zoo/. Aiaeiger 39: 719-723.

Jeffreys. 1862. British Conchology 3: 373.

Pelseneer, Paul. 1920. Les Variations et Leur H^redite

chez les Mollusques, L'Academie Royale de Belgique.

Richards. C. S. 1969. Genetic Studies on Biomphalaria

glabrata: Tentacle and eye variations. Malacologia 9(2):

.327-338.

Wong, L. W. and Wagner. E. D. 1956. Some effects of ul-

traviolet radiation on Oncomelania iwsophora and O.

quadrasi. snail intermediate hosts of Schistosoma Japoni-

cum. Ti-nns. Amer. Micro. Sue. 75: 204-210.

54 thp: nautilus

January 30. 1976

Vol. 90 (1)

•OBSERVATIONS ON MOLLUSKS FROM A NAVIGATION BUOY

WITH SPECIAL EMPHASIS ON THE SEA SCALLOP

PLACOPECTEN MAGELLANICUS

Arthur S. Merrill

National Marine Fisheries Service

Middle Atlantic Coastal Fisheries Center

Resource Assessment Investigations

Oxford, Maryland 21654

and Robert L. Edwards

National Marine Fisheries Service

Northeast Fisheries Center

Woods Hole, Massachusetts 02543

ABSTRACT

Tuwlve species of postlarval mollusks were found among fouling organisms

collected from a navigation buoy. Length data for the three most abundant

species, Placopecten magellanicus, Anomia aculeata. and Mytilus edulis. were

analyzed in an attempt to explain normal and log-nonnal frequency distribution

patterns. Molluscan community relationships on the buoy were closely observed

and reported. The ocean bottom under the buoy was sampled by dredge, and

the population composition of mollusks on the bottom did not include the

postlarval forms found on the buoy.

INTRODUCTION

Many objects floating at the ocean's surface

eventually acquire an imposing community of

sessile marine organisms. An impressive body of

literature exists with reference to such fouling

organisms (Woods Hole Oceanographic In-

stitution Contribution No. 580, 1952). In this

paper, we present the results of a study of the

mollusks attached to an ocean buoy. One

specific purpose of this study was to learn more

of the early life history of the sea scallop,

Placopecten magellanicus (Gmelin).

United States Coast Guard navigation buoys

come in many shapes and sizes. Those for ocean

duty are usually made up of a suf)erstructure

carrying a Ught and a bell or whistle, a cylin-

drical float chamber, and a stabilizer to hold

the buoy upright. They are anchored to large

blocks of concrete by heavy chain.

Immediately upon launching, buoys become

attractive bases for colonization by marine

organisms. The organisms which settle, survive,

and grow are, for the most part, species which

are able to attach themselves securely. When

' Published previously in the October issue, Vol. 98. No. 4.

in an unsatisfactorj' manner, due to editorial carelessness,

and re-published correctly here without cost to the sub-

scriber.

the buoy is returned for cleaning and servicing,

the entire community of organisms can be con-

veniently observed and sampled. The outside

buoy surfaces are subjected to strong tidal

currents and wave action, which restrict at-

tachment to those organisms with the most

tenacious holdfasts. The inside of the stabilizer

tube (Fig. 1) offers a more sheltered en-

vironment with considerable, but gentler, water

exchange as the buoy surges up and down. Here

are found the densest populations, and here the

struggle for space is readily observed (Merrill,

1965).

FIG. 1. Ti/pwal iimngation buoy. Arrow indicates the

sheltered, inner portion of the stabilizer tube.

Vol. 90 (1)

January 30, 197(i

THE NAUTILUS 55

METHODS

The collection was taken from the Nantucket

Shoals Lightship (NSLS) buoy. The buoy was

placed on station October 8, 1957, at N. lat.

40°33'; W. long. 69°28', 1 mile north of the

Nantucket Lightship, and returned to the Coast

Guard Base at Woods Hole for cleaning and

repairs on May 10, 1958. It offered a par-

ticularly attractive fouling community for

study, since the buoy had been on station for

only a limited time (7 months), and during a

period when many species with pelagic larvae

were not spawning (the winter months).

The NSLS buoy is 24 ft long and its greatest

diameter is 9 ft. About half of the buoy is sub-

merged when in position. Collecting was restrict-

ed to the area 8 ft inward from the mouth

(bottom) of the buoy stabilizer, which is 2 ft in

diameter (see arrow. Fig. 1). This area, ap-

proximately 50 sq ft, was carefully scraped and

then wire-brushed to loosen many small in-

dividuals still hidden in crevices. The total sam-

ple of l'/2 gal (12 pt) was taken to the

laboratory for sorting, study, and analysis.

Since the buoy had been out of water about

3 weeks, the fouling community had dehydrated

slowly and was in excellent condition for collec-

tion and study. Much of the material consisted

of sizable thin pieces of rust (Fig. 2) with

animals and plants attached in their original

positions.

Measurements of mollusks were made to the

nearest 0.1 mm wath the aid of an ocular

micrometer. The greatest overall size, height or

length was used as the basic measurement.

.1 i

FIG. 2. A piece of iron n/st removed from within the

stabilizer tube of a buoy. The material dried slowly and a

number of organisms can be seen adhering in their original

positions.

Hydrographic data for the area were

available from the nearby lightship.

To compare the population of the buoy with

that of the bottom below, the area was dredged

on May 26, 1958, about 2 weeks after the buoy

was brought in. A 10-ft-wide sea scallop dredge

with a ^/4-inch stretched mesh liner was towed

from the Bureau of Commercial Fisheries

Research Vessel Albatross HI to make the

collection. The contents of a 5-min tow which

covered approximately 15,000 sq ft of bottom

area were analyzed.

RESULTS

Three species of pelecypods — the sea scallop,

Plaeopeden rnagellanicus, the jingle shell,

Anornia aculeata, and the common, blue mussel,

Mytilus edulis — dominated the community

found on the buoy. Because the two latter

species were so numerous, a 1-pt subsample (of

the 12-pt total sample) was taken and all

specimens were counted and measured. The

length-frequency distributions obtained of the

three most common mollusks are shovra in

Figure 3. As a check on the validity of this

subsample, all molluscan species in the total

sample, except the numerous A. actdeata and

M. edulis, were also counted and measured.

Figure 4 shows the frequency distribution of P.

rnagellanicus found in the total sample.

The frequency distributions in Figures 3 and

4 are strongly skewed to the right and only

that for M. edulis is obviously polymodal. In

the subsample, there were 731 P. rnagellanicus

with a range in size of 0.5-13.2 mm and a mode

at about 3 mm; 2,217 A. aculeata with a range

of 0.5-14.0 mm and a mode at about 4 mm; and

1,550 M. edulis with a range of 0.4-24.3 mm and

obvious modes at about 1.7 and 2.8 mm (Fig. 3).

In the total sample, there were 9,806 P.

rnagellanicus with a range of 0.5-13.4 mm and

modes at about 2.5 and 2.8 mm (Fig. 4).

The mussel produces a stout and intricately

woven byssus, and the jingle shell a short

thickened byssal plug, both of which are

capable of holding shell remains securely to a

substrate after drying. The thin byssal threads

of scallops become brittle upon drying and

break easily. Therefore, the size-frequency data

presented in Figure 3 for the mussel and jingle

56 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

5 6 7 e 9 10

LENGTH IN MILLIMETERS

FIG. 3. Size -frequency distribution of the three cvmmun moltiusk sjjccws found on the Nantucket Shoals Lightship buoy (1-

pt subsample).

shell are pwssibly more representative of the

total sample than for the scallop. Propor-

tionally, there were fewer small PUicopecten in

the pint subsample than in the total sample,

and the mode was about 0.5 mm higher. Ap-

parently, some of the smaller scallops settled to

the bottom of the original scrapings before the

aliquot was obtained. However, aside from these

<

O

a

2

U.

O

q:

lij

m

s

1}

z

LENGTH IN MILLIMETERS

FIG. 4. Size-frequency distribution of the sea scallops found on the Nantucket Shoals Lightship (moy.

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 57

-Calculated from i 12 aliquot of total sample.

minor differences, the scallop size-frequency

distribution in the aliquot (Fig. 3) is similar to

that in the total sample (Fig. 4).

All the moUusks collected from the buoy are

listed in Table 1, together with their size-

frequency by 1-mm groups. The size-frequency

of the shells of dead P. magellanicus and M.

edulis is also given. The total number of A.

aculeata and M. edulis is estimated on the

basis of subsample counts. TTie total number of

living mollusks from the 50-sq-ft area was

55,120 or an average of 7.7 individuals per

square inch.

The material obtained by dreding the bottom

under the buoy was compared with the sample

from the buoy (Table 2). The bottom was of a

mud-sand texture; the sand dollar,

Echinarachnius parma, proved to be the com-

monest species of the area with over 1,200 cap-

tured. Some of the larger gastropods such as

Lunatia heros and Buccinum undatum were

present in fair numbers, and there were many

dead double valves of the bivalve, Arctica islan-

dica. The molluscan faunal composition of the

bottom was completely different from that of

the buoy except that it contained a few large

sea scallops. None of the same larval mollusk

species that had settled on the buoy found their

wav to the bottom in this area.

TABLE 2. Number of live and dead mollusks collected in

the dredging of a 5-min tow on May 28. 1958, in the area

of the Nantucket Shoals Lightship buoy.

Number of specimens

*«"«« Live Dead

Gastropoda

Cotus pygmaea Gould

Nassari.us trivittatus Say

Buccinum undatum Linnaeus

Lunatia heros Say

Crepidula plana Say'

Pelecypoda

Placopecten magellanicus Gmelin'

Artica islandica Linnaeus'*

Ensis directus Conrad"*

Astarte castanea Say

Venericardia borealis Conrad

Modiolus modiolus Linnaeus

Anomia simplex d'Orbigny

Spisula solidissima Dillwyn''

- This species had deposited numerous egg cases on the in-

terior of practically every dead valve of the mahogany clam

{Arctica islandica).

' Found attached inside large dead shells, usually Lunatia

heros.

' The heights of these in millimeters were 59.9, 85.2, 117.8,

131.7. 1.57.4, 164.7; one upper valve, 28.2

'' The animal lives in the substratum, consequently not

adequately collected by the type of dredge used.

DISCUSSION

Each species exhibited patterns of preference

in utilizing the substrate within the 8-ft length

58 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

of buoy tube. The spat of Mytilus, for example,

first attached directly to the substrate, and

later tended to aggregate and intermingle their

byssal threads to form colonies. Even thou^

the mussel may detach and reestablish

elsewhere (Field, 1922), our observations showed

that in some cases unusually dense masses of

byssal threads may entrap certain segments of

a population. As a result, some mussels became

smothered, or grew at a slower rate than neigh-

boring specimens. Anomia spat attached directly

to solid substrate, preferring crevices, but did

attach to all other available surfaces. Individual

Hiatella were randomly distributed and grew

competitively within aggregates of mussels, or

freely on open substrate. The spat of Plcwopec-

ten showed a marked preference for areas that

were free from other mollusk association. The

smallest scallops, those under 1 mm, were in-

variably attached to the filaments of bryozoa,

to the byssal threads of Mytilus, or directly to

shells, where they could move about freely.

Scallops over 1.5 mm were generally attached to

solid substrate, far removed from other

organisms, when possible.

Young sea scallops do not seem to compete

well in fouling communities. The mantle is ap-

parently easily injured, and evidence of serious

shell malformation was seen in situations where

other organisms were in close proximity to the

scallop. This was particularly noticeable when

an occasional larger specimen had been trapped

within the byssal maze of a Mytilus colony.

Young Anomia, Mytilus. and Hiatella, unlike

Placopecten, adjust to the necessity for living

close to other organisms. Anomia conforms

easily to close contact; if an obstacle in the im-

mediate area interferes with normal develop-

ment, the individual will change shell symmetry

and become elongate in any plane which offers

the opportunity for further growth. Mytilus and

Hiatella suffer least from close contact,

probably because their siphons, not their mantle

edges, are most exposed. However, both species

are known to exhibit shell distortion in con-

ventional habitats — Hiatella in peat and coral

burrows, and Mytilus in dense colonies.

Baird (19.53), in examining many "bushy"

organisms obtained from dredgings, found only

the bryozoan Gemellaria to be a consistent host

for settling sea scallop larvae. He suggested the

possibility of a direct relationship between

Gemellaria and Placopecten in the larval

ecology of the scallop. In light of our ob-

servations, we wash to amend this slightly. Ap-

parently when the scallop spat settles, it is too

delicate to take advantage immediately of bot-

tom substrate, composed entirely of particulate

matter continuously shifting with the bottom

currents. Thus, those that land on sedentary

branching plants and animals, or any other

hard .mrface on or above the ocean floor which

offers freedom of shell movement on all sides,

may have a distinct survival advantage.

It should be noted that, as with Placopecten.

many of the smallest individuals of Mytilus and

Anomia were attached to bryozoa and to byssal

threads; however, just as many of the smallest

were attached to solid substrate. From ob-

servations on the distribution of these species

in the buoy, it appears that all are able to

disengage themselves and travel some distance

—the mussels to aggregate, the scallops to

spread out, and the jingle shells to seek any

solid substrate available. Mytilus and Anomia

appear to fix more or less permanently at an

early age, while Placopecten and Hiatella may

continue to disengage from time to time.

Several of the smallest scallops from the buoy

measured as little as 0.5 mm. The prodissoconch

measured about half this size, so these smallest

specimens had approximately doubled in size

since settling. To our knowledge, these are the

smallest metamorphosed sea scallops ever col-

lected.'

After death, the ligamental structure in the

hinge of the scallop continues to hold the valves

together, but gaping. In this condition, sea

scallop valves tend to tangle in filamentous

bryozoa or amongst the byssal threads of the

mussels. There were 233 dead specimens of

scallops in the total population, the mode at

about 2.0 mm. Size-frequencies for the dead and

live scallops (Table 1) show similar curves

which suggests that valves do not remain long

in the buoy after death. The pint sample con-

tained 214 dead mussels (Fig. 3, dotted line),

' We have since taken from buoys scallops as small as 0.3

mm. the prodissoconchs having barely a fringe of dissoconch

growth.

Vol. 90 (1)

January 30, 1976

THE NAUTILUS 59

many of them of smaller size. In fact at about

1.2 mm, more dead than live mussels were

counted. Some of these were found trapped in

aggregates of mussels, while many were found

partly or completely buried in the light layer

of fine silt and debris that builds up in the

buoys. The great mortality in the smallest

mussels occurred over a period of time, judging

from the various degrees of shell decomposition

observed. The top and bottom valves of A.

acideata? soon separate after death and shell

remains are quickly flushed from the buoy;

hence, dead specimens are rarely found.

In order to discuss growth, the time of set-

ting must be ascertained with some degree of

accuracy. It is possible to determine quite

closely the spawning season (and hence the

probable time of setting) for two of the major

species on this buoy. Observations on the

spavraing of sea scallops have been made by

several investigators. These observations have

been summarized by Dickie (1955, p. 848) and

show that the spawning period, for all

geographical areas, may extend from mid-July

to early October. From extensive study, we can

definitely state that scallop spawning in the

offshore area of Cape Cod occurs between late

September and the middle of November.

Allowing as much as an extra month in the

larval state, all spat should have settled by

mid-December. This means larvae of the sea

scallop could, and probably did, settle on the

buoy during the first few weeks after it was

placed on station, and, judging by the

similarity of their population structures, so did

the other species as well.

In Milford Harbor, Connecticut, spawning of

M. eduiis is restricted to those months when

the temperature is approaching and above 60°F^

(Engle and Loosanoff, 1944). In "Marine Fouling

and Its Prevention" (Woods Hole Oceanographic

Institution, Contribution No. 580, 1952), early to

late June is indicated as the beginning of the

breeding season for Mytilus at Woods Hole,

Massachusetts. Mytilus larvae, then, must have

been in the water after the buoy was placed on

station, and, because of the low temperatures

that prevailed, there could have been no further

sets in the spring before the buoy was taken

off station. No spawning information is

available for A. aculeata, but the size-frequency

distribution suggests that the spat of this

species settled about the same time as the other

two species.

Both M edulvi and A. acvleata showed signs

of polymodal distribution not obvious in P.

magellanicus. The use of probability paper in

an attempt to define polymodal distribution as

outlined by Harding (1949) failed to show any

significant secondary set or group for the sea

scallops. However, similar analysis of the

Anomia data indicated possible modes at 3.7

mm and 7.2 mm, and for the mussel at 1.6 mm,

2.8 mm, 7.0 mm, and possibly others. This

suggests that, within the spavming period, one

strong set of sea scallops and two or more

heavy sets for the other two species settled on

the buoy.

From observations of the buoy material, there

is indirect evidence that more than one group

of larvae settled. For instance, many small

Anomia were seen attached to larger shells of

the same species; a small Anomia and a small

Mytilus were found attached to the inner valve

of a much larger dead mussel; and there were

many instances in which one organism grew

upon another in such a way as to suggest that

it set some time after the other. Indirect

evidence can also be found in the data; for in-

stance, the smallest mussel was 0.4 mm and the

largest just under 25 mm — far too much dif-

ference in growth, it is felt, for a single set.

The average and maximum sizes of the four

common species of pelecypods found in the buoy

were:

' Abbott in the second edition of American Seashelk (1974.

p. 452) follows Winckworth, 1922, and others, in calling this

species squamida Linne, 17.58.

' Temperature records for the time and locality involved in

this study are available in published form (Day, 1959a;

1959b).

The averages represent shell growth for 6 to 7

months after setting, and during the coldest

months of the year. The maximum sizes at-

tained are an indication of the amount of

60 THE NAUTILUS

January 30, 1976

Vol. 90 (1)

growth that can be achieved under the existing

conditions.

The location of the NSLS buoy is such that

pelagic bivalve larvae could be transported from

many coastal areas, and this could effectively

extend the setting season. The currents that

sweep over Nantucket Shoals undoubtedly carry

planktonic larvae originally spawned in many

different estuaries and bays of the Massachu-

setts coast, as well as from a large area of the

Gulf of Maine. It seems most reasonable to

suggest that, for Mytilus at least, the peak of

setting may have occurred for several weeks af-

ter the buoy was on station. Initial settlers

would have had less competition from their own

kind, as well as a warmer and longer period in

which to grow.

It should be pointed out that a factor such as

overcrowding might lead to arrested growth.

Arrested growth in one segment of the

population might yield a mode that possibly

could be interpreted as indicative of age.

The strongly skewed size distributions of

Figure 3 deserve further mention. Such

distributions are not uncommon in youthful

populations of many organisms, and can con-

ceivably arise in one or more ways, including

(1) simple differences in growth due to time of

setting, especially when spatfall occurs over a

period of time associated with a change in tem-

perature; (2) decreased grow1;h rate for later

arrivals due to increased density and com-

petition; and/or (3) some characteristic of the

buoy that causes unusual mortality (or loss to

the buoy) amongst the larger individuals.

The sea scallop size-frequency is well fitted

by a log-normal transformation, as can be seen

in Figure 5. The length -frequencies of Mytilus

and Anomia are not so well fitted, perhaps

because more than one set is represented in the

data. However, since any one or any com-

bination of the factors mentioned above can

result in a log-normal distribution, this trans-

formation does not of itself shed additional

light on the subject.

It would appear that the observed skews can

be largely attributed to setting over a period of

time during which sea surface temperatures

were cooling. The possibility that many Mytilus

and Anomia settled after temperatures were too

cool for any further significant growth cannot

ID

s

I 2 3«56789I0

LENGTH IN MILLIMETERS

P'IG. 5. Size-freqtiency distribution of the xea scallops

found on the Nantucket Shoals LighUhip buoy plotted on

semilngarithmic paper to produce the symmetry of a log-

normal curve.

be dismissed. The problem is worthy of further

study, and material from buoys may be par-

ticularly useful in this respect.

SUMMARY

1. All the mollusks within an area of 50 sq

ft were collected from within the stabilizer tube

of a heavy duty navigational buoy. Twelve

species were recovered from approximately

55,000 mollusks that made up the fouling

population. Three species, Placopecten

mayellanicus, Anomia aculeata, and Mytilus

edulh were found in the largest number.

2. The ocean bottom under the buoy was

dredged, and the population composition and

structure were found to be completely different

from the buoy population.

3. The population structure and the in-

terrelationships of species in the mollusk com-

munity were closely observed. Methods of at-

tachment and distributional patterns, par-

ticularly patterns of preference in utilizing sur-

face area, are discussed in some detail.

4. Analysis of the length-frequency

distribution, using probability paper to define

polymodal groups, suggested one heavy set of P.

mayellanicus and two or more of A. aculeata

and M. edulis.

5. Taking into consideration the season and

Vol. m (1)

Januarv 30. 1976

THE NAUTILUS 61

length of time the buoy was on station (7 months

from October 8. 1957, to May 10, 1958) and

using available evidence regarding the time in

which sea scallops and mussels spawn, it was

possible to predict that these species had settled

on the buoy before the first of the year. Hence,

growth was related to the size-frequency

distribution after that time.

6. Size-frequency graphs for the three com-

mon species on the buoy show that large num-

bers of small individuals form obvious modes

and that a persistent but diminishing number

of larger specimens spread over a considerable

range; i.e., the major modes for the three

species are skewed to the right. Possible reasons

for such size-frequency distribution are

discussed.

ACKNOWLEDGMENTS

We wish to acknowledge the cooperation of

the Commander of Base, U. S. Coast Guard

Station, Woods Hole, Massachusetts, and other

base personnel who assisted in the collection of

samples. The writers are grateful to Dr. L. B.

Slobodkin for helpful suggestions relative to

distribution of animals.

LITERATURE CITED

Baird. F. T. Jr. 1953. Observations on the early life his-

tory of the giant scallop (Peclen magellanmut). Maine

Dep. Sea Shore Fish., Res. Bull. No. 14, pp. 2-7.

Day, C. G. 1959&. Oceanographic observations, 1957, east

coast of the United States. U.S. Fish Wildl. Serv., Spec.

Sci. Rep.-Fish. No. 282, 123 pp.

Day, C. G. 1959b. Oceanographic observations, 1958, east

coast of the United States. U.S. Wildl. Serv., Spec. Sci.

Rep.-Fish. No. 318, 119 pp.

Dickie, L. M. 1955. Fluctuations in abundance of the giant

scallop, Ptacnpecten magellanicus (Gmelin), in the Digby

area of the Bay of Fundy. J. Pish. Res. Board Can.,

12: 797-857.

Engle, J. B. and V. L. Loosanoff. 1944. On the season of

attachment of larvae of Mytilva edulis Linn. Ecology.

25: 433-440.

Field, 1. A. 1922. Biology and economic value of the sea

mussel, Mytihis eduiu!. U.S. Bur. Fish... Bull. 38: 127-259.

Harding, J. P. 1949. The use of probability paper for the

graphical analysis of polymodal frequency distribution.

J. Mar. Biol. Assoc. U.K.. 38: 141-1.53.

Merrill, A. S. 1965. The benefits of systematic biological

collecting from navigation buoys. ASB Bull.. 12: 3-8.

Winckworth. R. 1922. Note on the British Species of

Anomia. Proc. Malacological Soc. London, 15(1): 32-34.

Wcx)ds Hole Oceanographic Institution. 19.52 "Marine Foul-

ing and Its Prevention." U.S. Naval Inst., Annapolis, Md.

Prepared for Bur. Ships, Navy Dep., by Woods Hole

Oceanogr. Inst., Contrib. No. 580). 388 pp.

62 THE NAUTILUS

January 30, 1976

THE BEST OF THE

A Bicentennial Anthology

of American Conchology

Edited by R. Tucker Abbott

From the first 40 years of The Nautilus 100 of

the most interesting and significant articles are

reproduced with modern day perspectives by

the editor. The 288-page book is replete with

conchological lore, quaint ads, and chamiing

accounts of shell collecting in pioneer America.

Come down the Mississippi in a boat on a unio-

hunting trip with F. C. Baker in 1902; venture

with Charles Hedley on his first helmet dive on

an Australian reef in 1894; go "ligging" with C.

T. Simpson in 1921; join James Ferriss and

George Clapp in 1899 at Clingman's Dome in

the Great Smoky Mountains; and laugh with

Abe Loche, a policeman of Atlantic City, who

was felled by a clam dropped on his head by a

seagull in 1925.

A UNIQUE ADDITION TO ANY

CONCHOLOGICAL LIBRARY

a sumptious and appropriate

Bicentennial Gift

Available in three forms

March 15, 1976

REGULAR" Library Edition

A handsome, durable hardback edition bound in simulated

leather and of the highest quality of printing, with marble-

ized end papers. A dozen well-known shells are shown in

full color. Only $13.95.

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Only a few numbered copies are available and only by ad-

vanced subscription; each is handdated, numbered and per-

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matched with a specially designed, presentation slip box.

.$3«.(K1. Offrniiii cliKiK the Fmiiili „f .Jiili/. i:i7r,.

Exquisite Offer: For the investor and ainnciis.seur's

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imported, Scottish leather of the highest quality appro\e<l

by the Briti-sh Museum. Your copy vrill be autographed,

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request.

Send check or money order to:

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P.O. Box 4208

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INFORMATION FOR SUBSCRIBERS

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MOLLUSK VOUCHER SPECIMENS

It is becoming increasingly important for

future research purposes that an identified sam-

pling of species mentioned in publications be

deposited in a permanent, accessible museum

specializing in mollusks. This is particularly

true of mollusks used in physiological, medical,

parasitological, ecological, and experimental

projects.

The Delaware Museum of Natural History

has extensive modem facilities and equipment

for the housing and curating of voucher

specimens. Material should be accompanied by

the identification, locality data and its

bibliographic reference. There is no charge for

this permanent curating service, and catalog

numbers, if desired, will be sent to authors

prior to publication.

APRIL 1976

THE

NAUTILUS

Vol. 90

No. 2

A quarterly

devoted to

malacology and

the interests of

conchologists

Founded 1889 by Henry A. Pilsbry. Continued by H. Burrington Baker.

Editor-in-Chief: R. Tucker Abbott

EDITORIAL COMMITTEE

CONSULTING EDITORS

Dr. Arthur H. Clarke, Jr.

Department of Mollusks

National Museum of Canada

Ottawa, Ontario, Canada K1A-0M8

Dr. WUUam J. Clench

Curator Emeritus

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. William K. Emerson

Department of Living Invertebrates

The American Museum of Natural History

Newr York, New York 10024

Mr. Morris K. Jacobson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 10024

Dr. Aurele La Rocque

Department of Geology

The Ohio State University

Columbus, Ohio 43210

Dr. James H. McLean

Los Angeles County Museum of Natural History

900 Exposition Boulevard

Los Angeles, California 90007

Dr. Arthur S. Merrill

Biological Laboratory

National Marine Fisheries Service

Oxford, Maryland 21654

Dr. Donald R. Moore

Division of Marine Geology

School of Marine and Atmospheric Science

10 Rickenbacker Causeway

Miami, Florida 33149

Dr. Joseph Rosewater

Division of Mollusks

U. S. National Museum

Washington, D.C. 20560

Dr. G. Alan Solem

Department of Invertebrates

Field Museum of Natural History

Chicago, Illinois 60605

Dr. David H. Stansbery

Museum of Zoology

The Ohio State University

Columbus, Ohio 43210

Dr. Ruth D. Turner

Department of Mollusks

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. Gilbert L. Voss

Division of Biology

School of Marine and Atmospheric Science

10 Rickenbacker Causeway

Miami, Florida 33149

Dr. Charles B. Wurtz

3220 Penn Street

Philadelphia, Pennsylvania I9I29

EDITOR-IN-CHIEF

Dr. R. Tucker Abbott

Delaware Museum of Natural History

Box 3937, Greenville, Delaware 19807

Mrs. Horace B. Baker

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Second Class Postage paid at Wilmington, Delaware

Subscription Price: $7.00 (see inside back cover)

THE

NAUTILUS

Volume 90, number 2— April 27, 1976

CONTENTS

Notices; Review (of R. T. Abbott) iv

Gale G. Sphon

The Mitridae of the Galapagos Islands 63

Robert S. Voss

Observations on the Ex»logy of the Florida Tree Snail, Liguus fasciatus Muller ) 65

Walter B. MiUer

New Species of Sonoreiia (Pulmonata: Helminthoglyptidae)from New Mexico and Texas 70

Clyde A. Henry

The Commensal Clam, Paramya subovata Bivalvia: Myidae) and Thdassema hartrmni

(Echuroidea) off Galveston, Texas 73

John Ogle

The Occurrence of the Date Mussel Lithophaga bisulcata (Mytilidae) in Living Oysters, off

Galveston, Texas 74

G. L. Mackie, S. U. Qadri andA. H. Clarke

Reproductive Habits of Four Populations of Musculium securis (Bivalvia: Sphaeriidae) near

Ottawa, Canada 76

Leslie Hubricht

The Genus Fontigem from Appalachian Caves (Mesogastropoda: Hydrobiidae) 86

Warren S. Landers

Reproduction and Early Development of the Ocean Quahog, Arctica islandica, in the

Laboratory 88

Publications Received 92

NOTICES

WESTERN SOCIETY OF MALACOLOGISTS

The ninth annual meeting of the Western

Society of Malacologists will be held from June

23—27, 1976, on the Asilomar State Conference

Grounds, Pacific Grove, California. The program

will feature contributed papers, symposia,

displays, shell auction and field trips. Send

inquiries to Mr. Clifton Martin, 324 Kennedy

Lane, Oceanside, California 92054.

1976 AMU MEETING

The meetings will be held on the campus of the

Ohio State University, Columbus, with

registration Monday afternoon (Aug. 2) and the

opening of the sessions that evening. Air-

conditioned rooms with private bath at the

University Residence Halls are only $11.00 per

single and $15.00 per double occupancy. Banquet,

Thursday, Aug. 5; Field Trip, Friday, the 6th.

Amateur night will feature a shell book auction

and bazaar. Forms will be mailed to members in

May. Inquiries: AMU '76, Museum of Zoology,

Ohio State University, 1813 North High Street,

Columbus, Ohio 43210.

REVIEW

THE BEST OF THE NAUTILUS. A bicenten-

nial Anthology of American Conchology. By

Abbott, R. Tucker (editor). 1976. viii 4- 280

pp. American Malacologists, P.O. Box 4208,

Greenville, Delaware 19807. $13.95.

In this Bicentennial year it is most appropriate

to look back over "the best of the Nautiliwi."

Dr. R. Tucker Abbott, current editor-in-chief of

the Nautilius has done this for us, and for our

pleasure and enlightenment he has assembled a

special volume to serve both as a source of

some classic studies in early American con-

chology and of some historically interesting

papei-s not available to those who do not have

a complete set of the Nautilus. Not only

original papers are included, but brief notes,

news items, obituaries, advertisements and ex-

change offers (but don't answer any of them!)

are sprinkled throughout. There is something

here for everyone— reports for the serious stu-

dent, advice for the shell collector, warnings for

the environmentalist, nostalgia for the anti-

quarian, oddities for the curious, and humor for

everyone. Even verse is included. Everyone will

appreciate "Salute to the Nautilus.", a verse by

Henry Dodge, the only piece not originally

published in the Nautilus, and the only item of

recent date. Stress is given throughout the

volume to the romance of shell collecting and

the human side of malacology.

Coverage is the first 40 years of publication

(1886-1926), out of a total of 90 years, begin-

ning with a reproduction of the postal card

which formed issue No. 1 of Volume 1, then

known as The Conchologists Exchange, and

Pilsbry's introduction to the Nautilus, beginning

with Volume 3.

Selections are grouped according to

geographic areas— the Atlantic Coast, the Pacific

Coast; the major habitats— land, fresh-water,

marine; foreign collecting; departed friends;

and miscellaneous. Familiar names of the giants

of conchology— Pilsbry, Sipipson, Johnson,

Clench, Henderson, Roper, Morse, Winkley,

Keep, Fred Baker, Frank Baker, Oldroyd, Eyer-

dam, Ferriss, Frierson, Cockerell, Goodrich,

Walker, etc. appear on every page. Many ar-

ticles are prefaced with editorial notes of a

biographical nature.

Illustrations include a color plate of 11

selected, colorful marine, freshwater, and land

shells, many drawings of shells, diagrams of an-

tique apparatus (in the ads), and reproduction

of the original figures illustrating each article.

Having read through many volumes of the

Nautilus for my own studies, and as official

abstractor for Biological Abstracts over a long

period of time, I can assure the reader that

Tucker Abbott has made a most interesting

selection of material to exemplify what profes-

sional and amateur conchologists and

malacologists were doing, thinking, and writing

to advance the study of mollusks over the first

40 years of the Nautilm. and to share with us

the excitement they experienced.

Ralph W. Dexter

Dept. of Biological Sciences

Kent State University

Kent, Ohio

IV

Vol. 90 (2)

THE NAUTILUS

63

THE MITRIDAE OF THE GALAPAGOS ISLANDS

Gale G. Sphon

133 W. Channel Rd.

Santa Monica, Calif. 5X)402

ABSTRACT

Eleven species of Mitridae are known to occur in the Galapagos archipelago.

Of these, thrve are endemic. The range of Mitra mitra is extended to include

the Eastern Pacific. The generic or s^ibgenenc standing of four species is

changed. A new secies, Subcancilla edithrexae, is described from the Galapagos

Islands.

The family Mitridae ranks as one of the

largest in the molluscan phylum. Cemohorsky

(1970) recorded over 800 valid species and

stated that 2624 names had been proposed. The

majority of mitrids are found in the Indo-

Pacific. In the Eastern Pacific, I recognize

about 30 valid species. Within the Galapagos

Islands, this number is reduced even further.

As far as I have been able to determine there

are only eleven species occurring in the ar-

chipelago.

First, a new record for the E^astem Pacific:

Mitra (Mitra) mitra (Linnaeus, 1758). In the

Indo-Pacific this is a very common species, but

Eastern Pacific records are based on only three

specimens, one adult living specimen taken off

the coast of Costa Rica and two adult, but

dead, specimens dredged by Jacquline and An-

dre DeRoy in the Galapagos. The DeRoys re-

tained one specimen for their own collection

and deposited the other at the Charles Darwin

Research Station. The Costa Rican specimen is

in the collection of the Los Angeles County

Museum of Natural History.

The next species is Mitra (Isara) effusa

Broderip, 1836. Mitra effusa is not common

anywhere within its range from Mazatlan, Mex-

ico, to Ecuador and the Galapagos. However, it

has been dredged in several locations in the

Galapagos by the DeRoys. Cemohorsky (1970)

synonomized the subgenus Isara with Mitra s.s.

However, the shape of the shell with its droop-

ing lip is distinct enough to warrant its separa-

tion as a valid subgenus.

The third species is evidently endemic to the

archipelago. This is Mitra (Mitra) gausapata

Reeve, 1845. Keen (1971) placed this species in

the subgenus Strigatella. I am here reassigning

it to the subgenus Mitra based on the radula

and shell morphology. Apparently this is one of

the sand-dwelling Mitra and occurs subtidally

throughout the archipelago. It appears to be

relatively common within its restricted range.

The fourth species is Mitra (Mitra) crenata

Broderip, 1836. Again, the subgenus is changed

here from Strigatella to Mitra s.s. Specimens I

have seen indicate that it is probably a good

species and not the young of something else,

even though at the present time the radula is

still unknown. The range of the species is from

Guaymas, Sonora, Mexico, south to and

throughout the Galapagos Islands.

Its authors put Subcancilla sphoni (Shasky

and Campbell, 1964) in the subgenus Strigatella.

Keen (1971) questioned this. Neither the shape

nor the spiral sculpture are characteristic of

Strigatella and it is here changed to the genus

Subcancilla. It ranges fi-om Guaymas, Sonora,

Mexico, to the Galapagos Islands.

The sixth species is a common intertidal

species throughout most of its range, from the

head of the Gulf of California to Peru.

However, Mitra (Mitra) lens Wood, 1828 is rare

in the Galapagos. To my knowledge it has only

been taken once in the Archipelago at Academy

Bay, Santa Cruz Island by Carmen Angermeyer

in 1964. This specimen is now in the American

Museum of Natural History. Mitra lens, also,

should be removed from the subgenus

Strigatella and placed in the subgenus Mitra on

the basis of the radular structure.

The seventh species is the only true

Strigatella in the Eastern Pacific and this is

Strigatella tristis (Broderip, 1836). This is prob-

m THE NAUTILUS

April 30. 1976

Vol. 90 (2)

FIG.l. Subcancilla edithrexae Sphon, iiew speaas. Huluti/ije

Length 22.6 mm. Width 9 mm.

ably the most common Eastern Pacific Mitra. It

ranges from the head of the Gulf of California,

south to Ecuador and the Galapagos Islands.

Although Strigatella is a large group, all

the members resemble one another in their

pyriform shape. Some authors have used Striga-

tella as a genus, and I tend to agree with them

even though there is little difference in the

radula of Mitra s.s. and Strigatella.

The next three species all belong to the genus

Thala. The type locality for Thala gratiosa

(Reeve, 1845) is the Galapagos and it has a

much larger range than the others, namely

from the Gulf of California to Panama. It has

also been, mistakenly, called Thala solitaria (C.

B. Adams, 1852). T. solitaria occurs from

- 1

\'j

Banderas Bay, Mexico, to the Galapagos and

was described from Panama. The true Thala

solitaria is one of the rarer Eastern Pacific

miters. The third species of Thala is T. jean-

cat eae Sphon, 1969 and it is known only fi-om

a half dozen specimens from the Galapagos.

The eleventh and last mitrid species is new

to science, and I take great pleasure in naming

it in honor of a very dear friend, Miss Edith

Rex.

Subcancilla edithrexae Sphon, neir species

Shell of moderate size, to 22 mm in length;

shape ovate with raised reddish brown ribs

about one quarter to one half the width of the

white interspaces; periostracum thin and

brownish; interspaces marked by numerous ir-

regular growth lines; columella with 3 or 4

plications; spire attenuate, angle acute; aper-

ture narrow, slightly more than half the shell

length; Radula formula 1-1-1; Triangular -shaped

rachidian wider than hi^, with 6 cusps, the

center 4 being of equal size and prominent, the

outer ones being one-third as large, a small

denticle present on the ends nearest to laterals;

laterals with eleven cusps, the two outer ones

mere denticles, next six progressively larger

nearing the median tooth; third cusp from the

median largest; innermost two reduced in size;

lateral tooth plate basically rectangular in

shape with slight curve to lower portion.

The holotype was collected by the Ameripagos

Expedition, in 10-20 feet of water on March 25,

1971. The type locality is Punta Alfaro, Isabela

Island, Galapagos Islands, Ecuador. It is

deposited at the Los Angeles County Museum

of Natural History (LACM 1735). There are

numerous paratypes in the following institu-

tions and private collections: American Museum

of Natural History; California Academy of

Sciences; Charles Darwin Research Station;

and several private collections.

/

FIG. 2. Radrtla of Subcancilla edithrexae Sphon. new

species (from a paratype).

LITERATURE CITED

Cernohorsky. W. 0. 1970. Systematics of the families

Mitridae & Volutomitridae (Mollusca : Gastropoda). Buil.

Aukland Inst, and Mus. no. 8, pp. 1-190 -I- iv, 18 pits.

Keen. A. M. 1971. Sea Shells of Tropical West America.

Stanford Univ. Press, Stanford, Calif, pp. 1-1064 -t- xiv.

Dlust rated.

Vol. 90 (2)

THE NAUTILUS

65

OBSERVATIONS ON THE ECOLOGY OF THE FLORIDA TREE SNAIL,

LIGUUS FASCIATUS (MULLER)

Robert S. Voss

Department of Ecology & Evolutionary Biology

Student Union P.O. Box 9743

Tucson, Arizona 85720

ABSTRACT

Four South Florida populations of Liguus fasciatus were studied over an

eight month period. Growth ivas calculated by means of size frequency diagrams

and age class groupings, and was found to be roughly linear. L. fasciatus

hatches at a size of 7 mm, grows aproximateiy 10 mm per year, and reaches

sexual maturity in its fourth year at a size of about ^8 mm. Copulation occurs

in the months of July. August and early September, and nesting follows in late

September. Mass mortality of adult snails was observed soon after nesting. The

young emerge with the rains in April and May, but are fully developed long

before. Tree snails are eaten by many vertebrates and invertebrates, and preda-

tion may exert a powerful selective pressure on this species. L. fasciatus

displays a marked preference for smooth barked host tree species, preferential

listings of which are included. L. fasciatus is not an endangered species in South

Floiida.

Liguus fasciatus (Mtiller) is a tree snail of

Antillean origins which probably arrived from

Cuba shortly after the emergence of the Florida

peninsula in the late Pleistocene. In Florida, L.

fasciatus is found exclusively in hammocks,

assemblages of tropical hardwood trees scattered

island-like in the 'Glades and pinewoods of the

extreme southern part of the state. Hammocks

provide Liguus protection from fire, predators,

cold spells, and dessication.

The species exhibits great variability in color-

ation of the shell which is often of striking

beaut>'. Consequently this snail has long been

popular with collectors, and an enormous

literature exists dealing almost exclusively with

its systematics and zoogeography. Surprisingly,

little has been published on the ecology of L.

fasciatus. What has been published on the sub-

ject consists largely of scattered notes, or pass-

ing references in larger, systematic works

(Pilsbn,- 1946, Simpson 1929, Weber 1953, etc.).

The best account to date is in a popular article

by Davidson (1965), but the ecological literature

on this snail is, as a whole, exceedingly sketchy.

It is hoped that this paper will help to fill this

gap.

METHODS

This study was carried out over an eight -

month period from August 1969 to March 1970

during which weekly field observations were

made. Attention was centered on four Liguus

populations, three on the east coast of Florida

near Miami (Matheson, Brickell, and Timm's

Hammocks) and one on the eastern edge of the

Big Cypress Swamp (Pinecrest #5, Pilsbn' 1946)

about fiftj' miles west of Miami.

Snails were sighted and collected either by

hand or with the aid of a "Lig pole", three in-

terlocking four foot aluminum tubes with a cup

on the end into which the snail was shovfed.

Measurements of living snails were taken in

the field: total length from the apex of the

shell to the base of the aperture.

Eggs were incubated in one-pint Mason jars

kept outdoors and occasionally sprinkled with

water. Young were maintained for short periods

66 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

in an indoor terrarium and provided with wet

bark on which to feed.

All of the dead shells on several square

meters of forest floor were collected for preda-

tion studies. When studying tree preference, the

hammock was "walked" and all trees closely

scrutinized for snails.

RESULTS AND DISCUSSION

Reproduction: Ligmis fasciatus mates in the

summer primarily in the months of July,

August and early September, which is the rainy

season. I have, however, observed copulating

pairs as late as September 20. Snails on trees

and on the ground often appear to follow the

mucus tracks of others, and individuals may

locate each other prior to mating in this way.

Mating was only observed on tiees. A long in-

terval of intertwining precedes copulation.

Gestation takes from three to six weeks, and

at the first heavy rain the snails descend to lay

their eg^. The nesting procedure is as follows:

the snail anchors pjart of its foot on the base of

the tree, and tentatively stretches out across

the leaf litter. Reassured, it releases its hold,

and begins probing the humus for a suitable

nest site. This operation may occupy some half

hour or more. After locating a spot, the snail

begins to pull itself into the humus by exten-

sions and contractions of the foot until only the

apex of the shell remains above ground. Here it

hollows out a nest in the earth consisting of a

vertical tunnel, 10 to 15 mm in diameter, which

widens to form a chamber for the eggs. The

depth of the nest varies from 40 to 50 mm. The

entire nesting process lasts between 59 and 75

hours, during which time the snail is extremely

vulnerable to terrestrial predators.

In 1969, snails were observed laying eggs only

from 14-27 September. The peak of ^g laying

activity was from the 14th to the 19th, after

some exceptionally heavy rains. Of nineteen

snails observed nesting in Matheson Hammock

on September 16, the range in clutch size and

mean clutch size was 14-19-30 eggs. The range

in size and average size of nesting snails was

40-48.3-60 mm. No correlation was observed be-

tween size of snail and clutch size. The eggs of

L. fasciatus are oval, 6.5-8.0 mm long and 5.5-

6.0 mm wide, brittle, and pinkish brown

(Ridgway's Color Guide's Light Vinaceous Fawn

(Weber 1953)) in color.

Many snails die soon after nesting. This is

evidenced by the disproportionately large

numbers of freshly dead snails observed for a

month or so after the egg laying period, a phe-

nomenon also noted by Simpson (1920). This

field observation was later verified by examin-

ing size frequency diagrams (Figs. 1 arid 2).

Here, it is seen that the number of snails per

size range drops off considerably for sizes

greater than 48 mm, the average size at

nesting, indicating low post -reproductive sur-

vivorship. High post-reproductive mortality may

10

20 30

size (mm)

40

50

FIG. 1. Size frequency distribution of a sample of 52

LiguusyroTW Tlmm 's Hammock.

c

in

i)

n

E

C

10

20

30 40 50 60

size (mm)

FIG. 2. Size frequency distribution of a sample of SU

Mgwjsfrom Brickell Hammock.

Vol. 90 (2)

THE NAUTILUS

67

function to reduce competition between non-

productive adults and their potentially produc-

tive young.

Hatching occurs after the first heavy rains in

April or May apparently due to increasing

warmth and moisture, as the snails are fully

developed after six weeks (Weber 1953). Snails

removed from the egg by me after fifteen

weeks, and provided with wet bark to feed on,

began to grow immediately; snails left in the

^g did not hatch for another three months.

The newly hatched young measure 6.0-7.0 mm

long.

Aestivation and Feeding: During the winter

months from November to March, the dry

season in southern Florida, Liguus fasciatus

secretes a mucus seal which cements the shell

to the tree, protecting the animal from dessica-

tion. During this time the shell does not grow.

Upon resumption of feeding with the spring

rains, shell growth begins anew, and a growth

line appears where lip growth ceased during

the winter. By counting the number of these

grow^th lines, the age of the snail can be deter-

mined with a fair degree of accuracy. Occa-

sional winter rains may occur, and after these

snails may be seen feeding for a while before

resuming aestivation.

Liguus fasdatus is largely nocturnal, and is

most active after heavy rains which soften the

confervoid algae (Simpson 1929) and lichens on

which it feeds. This grovrth is abundant on tree

bark, the normal substrate for L. fasciatus. and

the feeding snail cuts visible swaths in this

growth as it moves.

Growth: In an organism such as Ligmis

fasciahis in which reproduction is seasonal,

discrete generations are present, and these

generations should appear as peaks of size fre-

quency when the measurements of large

numbers of individuals from a given population

are graphed. Such was found to be the case,

and graphs of size versus frequency for the

Timm's and Brickell Hammock populations are

given in Figures 1 and 2. Peaks represent suc-

cessive generations and the distance between

them a years growth. Averaging the data from

the two populations, and assuming that the

young hatch at a size of 7 mm, it is found that

L. fasciatus grows approximately 9 mm the

TABLE 1. Aivrage size of snails frmn three hammnrks

grmiped accirrding to anniud growth marks (total length in

mm.) M = Matheson Hammock; B = Bnckell Hammock;

T = Timm's Hammock; in the column "mean growth"

the snails assumedly hatched at 7 mm.

first year, 14 mm the second, 11 mm the third,

and 7 mm the fourth. Measurements throughout

were taken from the apex of the shell to the

base of the aperture.

A second method employed in estimating

growth was that, of grouping the snails by an-

nual growth marks (discussed in the preceding

section), and averaging the sizes of individuals

in each group. Year class averages calculated

by this method (Table 1) yield the following

figures for growth: first year 13 mm, second

year 9 mm, third year 9 mm, fourth year

9 mm.

Data derived from both of the above methods

were plotted on the same graph (Figure 3), and

growth (measured as total length) was found to

be approximately linear. Mean size of nesting

individuals was found to be 48 mm, and by

locating this size on the line fitted to the data

points in Figure 3, it is found that reproduc-

tion occurs at the end of the fourth year of

growth.

Tree Preference: While observing tree snails,

it was noted that they displayed a marked

preference for certain tree species. This ten-

• growth mark

o srze frequency

40

20

10

age (years)

FIG. 3. Size (total length) vs age for Liguus. Date derived

from size frequency diagrams and age class groupings.

68 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

TABLE 2. Host trees of 50 liguus from "nrnm's Hammock

TABLE 3. Host trees of 21 Liguus from Matheson

Hammock

Number uf snails

Host tree species

7 Strangler Fig Ficus aurea

2 Paradise Tree Simarouba glauca

2 Seagrape Coadoba uvifera

1 Mastic Ma,st ichodendron foetidissimum

1 Live Oak Qiiercus virginiana

1 Jamaica Dogwood Piscidia piscipula

7 Miscellaneous (ground, palmetto leaves,

dead wood, etc.)

dency has been noted before in the literature

(Simpson 1929, Craig 1973), but quantitative

data has not been made available.

The host trees of 50 Liguus fascial us were

tallied, and the results are given in Table 2

(Timm's Hammock). In this hammock, 65% of

the snails were found on Lysiloma, 9% on

Metopium, and 6% on Piscidia with the remain-

ing 20% being found sparingly on foiu" other

species.

The host trees for 22 Liguus fasciatus from

Matheson Hammock are listed in Table 3. In

this hammock, Lysiloma and Metopium are ab-

sent or scarce. The trees most frequented in

this case were F^us (32%), Simarouba (9%),

and Cocoloba (9%). An unusual number of

snails were found on atypical substrates on the

day when this survey was made.

Other trees on which I have commonly

observed Liguus are the Mastic (Mastich-

odendron foetidissimum), and the Guava

(Psidium guajava). Citrus groves in or near

hammocks are often found to contain numbers

of tree snails. Simpson (1929) found L. fasciatus

on cypress trees (Taxodium), and White But-

tonwood (Conocarpus erecta) in fresh and salt

water swamps respectively. It seems unlikely

that these represented breeding populations ron-

sidering the terrestrial nesting habits of these

snails. It is possible that Simpson's specimens

were isolated individuals accidentally dropped

by birds, or snails which had wandered away

from hammocks in the dry season, to be later

isolated by rising water.

It appears from the preceding data that L.

fasciatus strongly prefers certain tree species

over others. In each case, the preferred species

are smooth barked trees. On such trees there is

an abundance of algal growth on the bark, the

smooth surface of which permits the snail to

crawl easily, and presumably permits a long,

unobstructed sweep of the radula. It should be

noted however, that L. fasciotns will feed over

any smooth algae covered surface including con-

crete walls and the sides of wooden outhouses

(personal observations).

Predation: In southern Florida, Liguus

fasciatus is preyed upon by a wide variety of

vertebrates and invertebrates. While the con-

tribution of L. fasciatiui to the food budget of

individual predator species may be small, their

cumulative effect on tree snail populations may

be quite large.

The carnivorous gastropod Euglaruiina rosea

has long been known to devour L. fasciatus.

and Baker (1903) observed that it likewise

devours the much larger native tree snail

Orthalicus. Davidson (1965) observed and

photographed E. rosea predation on L. fasciatus.

E. rosea seems to be primarily a terrestrial

species associated with rocky substrates, but I

have often observed it on concrete walls, and it

may climb trees as well.

Pilsbr>' (1946) stated that he had "seen no

evidence that the tree snails are molested by

native birds", but friends have repeatedly

observed Blue Jays (Cyanocitta crista semplei)

devouring L. fasciatus. and I have frequently

noted broken shells in areas where other

predators are scarce. Further, the condition of

many freshly broken empty shells is ttx) intact

for any but a beaked animal to have removed

the snail.

Rats have often been reported as a m^or

predator on L. fasciatus. Pilsbry (1946) believed

that they would soon exterminate these snails

in all accessible hammocks. Timm's, Matheson

and Brickell hammocks have been surrounded

Vol. 90 (2)

THE NAUTILUS

for many years by human habitations, however,

and their snail populations continue to thrive.

Clench (1975) has suggested the ameliorating ef-

fec-ts which domestic cats and dogs may have

on the hammock rat populations, and contends

that rats may indeed prey rather heavily on L.

fasciatus.

The native land hermit crab, CoenoMta

dypeatus may also prey on tree snails. David-

son (1965) observed possible predation on L.

fasciatus by this crab, but in a fit of an-

throp(jmorphic compassion removed the crusta-

cean before it could eat (?) the snail. I have oc-

casionally seen crabs of this species inhabiting

tree snail shells in Brickell Hammock, but as

Coernibita wall occupy any suitable empty

gastropod shell it encounters, this cannot be

taken as proof of predation.

The land crab Cardisoma guanhumi may also

eat L. fasciatus, for its burrows are often sur-

rounded by the broken shells of this species.

Rhoads (1899) reported that L. fasciatus is

"eaten by tree crabs which bite the shell in

half during their winter hibernation". He cites

the occurrence of broken basal portions

cemented on trees as evidence. This seems an

unlikely hypothesis as Cardisoma does not

climb, and Coenobita, a good climber, seems too

small to break a snail shell in two: Davidson's

photograph shows Coenobita inserting its claws

into the aperture. I would imagine that Rhoad's

"tree crate" are in fact raccoons or oppossums

which frequently climb and have been reported

as preying on L. fasciatus.

Of 189 empty tree snail shells collected in the

leaf litter of Matheson Hammock (where all of

the above predators occur), 52% of the shells

were intact, indicating natural death or Eu-

glandina predation: ^% of the shells were

crushed leaving only the apex, suggesting rac-

coon, oppossum, rat, or crab predation. The re-

maining 10% were broken open on one side

only, suggesting predation by birds. These con-

clusions are only speculative, but if the sample

was a representative one, then it indicates that

nearly half of tree snail mortality is due to

predation, which must then be viewed as a

powerful selective force impinging on Ligmts

populations. K so, and if a significant number

of predators locate L. fasciat-us visually, then

the elaborate banding patterns of this snail

may have a much greater adaptive significance

than has been hitherto recognized. This is a fer-

tile field for further research.

Contrary to the cries of alarmist conserva-

tionists, Liguus fasciatvis does not appear to be

an endangered species in South Florida. It is

quite commonly found in the tropical hammocks

of the area, and these hammocks are largely

preserved within the county, state and federal

parks. It is true that certain local and rare

color varieties have been exterminated by col-

lectors and developers, but the species as a

whole continues to thrive.

ACKNOWLEDGMENTS

I wish to thank my parents. Dr. Gilbert L.

and Mrs. Nancy A. Voss for their constant

assistance and encouragement. I would also like

to thank Mr. Arthur Peavy, Director of Dade

County Parks, for permission to work with tree

snails in the county parks; Mr. John C. Eckhoff

for his enthusiasm and assistance: Mrs. Rita

Sturgeon of the Florida Department of

Agriculture: the Rosenstiel School of Marine

and Atmospheric Sciences for the use of its

library. I also extend my thanks to Dr. William

J. Clench for critically reviewing the

manuscript, and to Dr. Walter B. Miller for his

helpful suggestions.

LITERATURE CITED

Baker. F. C. 1903. Shells of land and water. A. W. Mum-

ford. Chicago.

Clench. W. J. 1975. Personal communication.

Craig, A. K. 1973. A new record for Ligmis: the Boynton

Beach colony. The Nautilus 87: 83-85.

Davidson, T. 1965. Tree snails, gems of the Everglades. Nail.

Geographic Mag. 127: 372-387.

Pilsbry, H. A. 1946. Land moUusca of North America. 2:

37-102.

Rhoads, S. N. 1899. Annotated list of land and fresh water

shells recently collected in the vicinity of Miami. Florida.

The Nautilus 13: '&-i7.

Simpson, C. T. 1920. In Lmver Florida Wilds. New York.

Simpson, C. T. 1929. The Florida tree snails of the genus

Lnjum. Prx. U.S. Nat. Mu.f. 73: 1-44.

Weber, J. A. 1953. Nests of the Florida tree snail.

Every ladf.'iNai. HkL Mag. 1: 63-65.

70 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

NEW SPECIES OF SONORELIA (PULMONATA: HELMINTHOGLYPTIDAE)

FROM NEW MEXICO AND TEXAS

W alter B. Miller

Department of Biological Sciences, University of Arizona,

Tucson, Arizona 85721

ABSTRACT

Two new species of land snails of the genus Sonorella (metcalfi and todseni)

a?-e described from Dona Ana Cminty, New Mexico, and El Paso County, Texas.

Sonorella orientis Pilsbry, 1936, was first col-

lected in 1897 by C. H. T. Townsend in

Fillmore Canyon, Organ Mountains, Dofia Ana

County, New Mexico, as stated by Pilsbry and

Ferriss (1905). The type lot, including live

snails, was cc^Uected by Ferriss and Pilsbry in

1922, at Dripping Springs in Ice Canyon, Organ

Mountains, just south of Fillmore Canyon, and

was described as a subspecies of Sonorella

hachitana (Dall, 1895) by Pillsbry (1936). I col-

lected it in Fillmore Canyon on 7 June 1965,

but was unable to obtain live specimens for

dissection. Subsequently, Artie L. Metcalf, of

the University of Texas at El Paso, sent me

live specimens from several localities in

Fillmore Canyon, Ice Canyon, and Rock Springs

Canyon. Dissection of several series of

specimens revealed that the reproductive

anatomy differed significantly from that of S.

hachitana. This information, plus evidence ob-

tained in my laboratory (unpublished hybridiz-

ing experiments) that S hachitana is ap-

parently an obligate calcicole, with peculiar

nutritional or growth factor requirements, were

considered sufficient to infer probable reproduc-

tive isolation and accordingly, Bequaert and

Miller (1973) raised S. orientis to specific rank.

Since 1967, Artie Metcalf and Thomas Todsen

have continued to collect in the Organ Moun-

tains, as well as in the San Andres Mountains

to the north, the Dona Ana Mountains to the

west, and the Franklin Mountains to the south.

They have kindly sent me many specimens

from their collections. Examination of shell

characteristics as well as reproductive anatomy

of the collected specimens reveals the presence

of two new species of Sonorella, one in the

Franklin Mountains and one in the Dona Ana

Mountains. I take great pleasure in naming

these new species after their discoverers. Dr.

Artie L. Metcalf of the Department of

Biological Sciences, University of Texas at El

Paso, and Dr. Thomas K. Todsen, of the White

Sands Missile Range, New Mexico. I also wish

to thank the Commander, White Sands Missile

Range, and his staff for permitting this scien-

tific exploration of the San Andres Mountains.

Sonorella metcalfi new species

Figs. 1 and 4

Description ofholotype. Shell depressed -globose,

heliciform, thin, glossy, light tan, with chestnut

spiral band on the well-rounded shoulder; um-

bilicate, the umbilicus contained 10 times in

the diameter and about '4th covered by the

reflected columellar lip. Embryonic shell of \Vz

V\C.\. Sonorella metcalfi. new species. W. R Miller. IHstal

reproductive xtntctures. Drawing made from stained whole

mount. Ahhreriatians: ec ep'phallic caecum: ep cpiphallus;

to free in'iditct: og ovidncnl gland: pe /lents: pr penial

retmctor: ps penial .<iheath: pt pro.'itate: sd spermathecal

duel: va iiigina: vd vas deferens: ve verge.

Vol. 90 (2)

THE NAUTILUS

71

FIG. 2. Sonorella todseni, new species, W. B. Miller. Distal

reproductive structures. Drawing made from stained whole

mount.

whorls, silky -smooth, not glossy, with light,

radial ripples and traces of descending, spiral

threads atxjve the suture, visible at about 10 X

to 20X magnification. Post-embryonic whorls

marked with light growth wrinkles. Last fourth

of body whorl with light, incised spiral lines,

most pronounced near shoulder. The peri-

ostracum has a silky, lustrous appearance. The

last whorl descends abruptly to the slightly ex-

panded peristome. Aperture oblique, rounded,

slightly wider than high, with margins converg-

ing; parietal callus thin. Shell measurements, in

mm: diameter 19.8, height 12.0, umbilicus 2.0,

AVa whorls.

Reproductive anatomy. The ovotestes, her-

maphroditic duct, seminal vesicle, albumen

gland, spermoviduct, spermatheca, and sper-

mathecal duct are typical of the genus. The

penis contains a long, thin cylindrical verge

bluntly rounded at its tip; the verge is slightly

less than half as long as the penis. A penial

sheath covers the distal half of the penis.

Epiphallus very thin distally, the distal end

embedded in the penial retractor muscle, then

enlarging proximally to its junction with the

vas deferens and the short, free, epiphallic

caecum. Vagina about '/4th the length of the

penis. Lengths, in mm, as follows: Penis 13;

penial sheath 6.5; verge 6; epiphallus 14;

epiphallic caecum 0.8; vagina 10.

Type Locality. North Franklin Mountain, El

Paso Co., Texas, in a northwest arm of

Fusselman Canyon, above spring. Latitude 31°

53.7' N, longitude 106° 29.0' W; elevation ca

5300 feet. Collector: Artie L. Metcalf, 11 May

1972.

Tyj^e Material. Holotype, United States Na-

tional Museum No. 760816. Paratypes: Delaware

Museum of Natural History, No. 99172;

Academy of Natural Sciences of Philadelphia,

No. 338227; Museum of Arid Land Biology,

U. T. El Paso, No. 4374, and the author. No.

59:38.

Distribution. Sonorella metcalfi is found in

the Franklin Mountains of Texas and in the

southernmost part of the Organ Mountains of

New Mexico. It has been collected at the follow-

ing localities: Franklin Mountains: (1) Several

localities in Fusselman Canyon, (2) Tom Mays

Park, 0.2 mi SW of West Cottonwood Spring,

(3) West slope of South Franklin Mountain, at

ca 5500 feet. Organ Mountains: head of Finley

Canyon at ca 6000 feet. All collections by Artie

L. Metcalf.

Sonorella todseni new species

Figs. 2 and 4

Description of holotype. Shell depressed-

globose, heliciform, thin, glossy, light tan, with

narrow, chestnut spiral band on the well-

rounded shoulder; umbilicate, the umbilicus

contained 7 times in the diameter and only

slightly covered by the reflected columellar lip.

Embryonic shell of IV2 whorls, dull with minute

radial ripples on which are superimposed many

spirally descending and ascending interrupted

threads and granules. Postembryonic whorls

marked with light growth wrinkles and

granules, the granules becoming absent on the

body whorl. The periostracum has a silky,

lustrous appearance. The last whorl descends

abruptly to the slightly expanded peristome.

Aperture oblique, rounded, slightly wider than

high, with margins converging; parietal callus

very thin. Shell measurements, in mm:

diameter 17.9, height 9.6, umbilicus diameter

2.6; 4' 4 whorls.

Repi-oductive anatomy. Ovot«stes and prox-

imal accessory structures as in other Sonorella.

The penis contains a long, thin, unevenly cor-

rugated verge tapering to a pointed tip; the

72 THE NAUTILUS

April 30, 197f;

Vol. 90 (2)

5mm

K1G.3. Sonorella orientis Pilahry. Distal reproductice.

structures. Dramng made from stained whole mount.

verge is about V3 the length of the penis. A

penial sheath envelops the distal third of the

penis. Epiphallus thin, the distal part embedded

in the penial retractor muscle; a very short,

free, epiphallic caecum is present. Vagina about

'4 the length of the penis. Lengths in mm, as

follows: penis 8, penial sheath 2.5, verge 5.5,

epiphallus 6.5, epiphallic caecum 0.7; vagina 6.

Type Locality. Dona Ana Mountains, Dona

Ana Co., New Mexico, on NW slope of Dona

Ana Peak (NW '4, SW '/i, NE %, Sec. 25, T 21

S, R 1 E); elevation ca 5300 feet. Collector:

Artie L. Metcalf, 28 August 1972.

Type Material. Holotype, United States Na-

tional Museum No. 760817. Paratypes: Delaware

Museum of Natural History, No. 99171;

Academy of Natural Sciences of Philadelphia,

No. 338228; Museum of And Land Biology,

U. T. El Paso No. 2809; private collection of

the author. No. 5973.

Distribution. Sonorella todseni is known only

from the Dona Ana Mountains of New Mexico,

a small, detached outlier of the Organ Moun-

tains, just north of Las Cruces. It was orig-

inally collected on 1 October 1967 by Dr.

Thomas L. Todsen (ALM #850; WBM #5023), a

small lot of shells only. Subsequently, a lot con-

taining one live adult was collected by Edward

Stern and Artie Metcalf on 23 January 1969

(WBM #5103). The type lot, consisting of many

live adults as well as shells only, was collected

by Artie Metcalf on 28 August 1972.

Remarks. Compared to S. metcalfi, S. todseni

has a generally smaller, lower, more widely um-

bilicate shell, with the umbilicus less covered

by the reflected- columellar lip. Fresh shells

tend to show heavier granulation under high

magnification. It is in the anatomy that dif-

ferences are more easily discerned. S. todseni

has a coarsely corrugated verge, tapering to a

FIG. 4, T(rp row, Sonorella todseni, new .•species, W. R

Miller. Middle row, Sonorella metcalfi, mw species, W. R

Miller. Bottom row, Sonorella orientis Pilsbry.

Vol. 90 (2)

THE NAUTILUS

73

pointed tip; the walls of the penial chamber

surrounding the verge are relatively smooth. S.

meicalfi has a nearly smooth, cylindrical verge,

bluntly rounded at its tip; the walls of the

penial chamber surrounding the verge are

thickened, glandular, and finely corrugated.

Although dimensions of anatomical structures

show much variability, certain length ratios,

such as verge/penis (ve/p), vagina/penis (va/p),

and penial sheath/penis (ps/p) appear to be

consistent and diagnostically useful. Approx-

imate values of these ratios are: S. todseni.

ve/p %, va/p Vi, and ps/p '4; S. meicalfi, ve/p

'/2, va/p ^4, and ps/p '-2.

Both 5. meicalfi and S. iodseni appear to be

closely related to S. oneniis Pilsbry 1936, and

all three species probably speciated relatively

recently from a common ancestral population.

S orieniis (Figs. 3 & 4) has a usually larger,

widely umbilicate shell. It has a long, coarsely

corrugated, tapering verge, in a smooth -walled,

capacious penial chamber with ve/p ca ^'3, va/p

ca 1 or >1, and ps/p ca Vj. S. orieniis is found

throughout the Organ Mountains except perhaps

the southernmost part (Finley Canyon) where S.

meicalfi is found; the possibility of their being

sympatric there needs to be confirmed by addi-

tional collecting and dissection. It is also found

in the San Andres Mountains (confirmed by

dissection, WBM#'s 5978 and 5983) where it has

been collected on Salinas Peak by Thomas

Todsen and Artie Metcalf (MALB-3145, WBM

5978) on 10 September 1972 and in Ash Canyon

by Artie Metcalf (MALB-3156, WBM 5983) on

23 September 1972. Shells from Sierra Blanca

Mountain (Pilsbry, 1936) and the Sierra Vieja

of Texas (Oieatum, Fullington, and Pratt, 1972)

may also be S mieniis but need to be ron-

firmed by dissection.

LITERATURE CITED

Bequaert, J. C. and W. B. Miller. 1973. Tlie mollusks of the

arid Southwest with an Arizona checklist. University of

Arizona Press. Tucson, Ariz. 271 pp.

Cheatum, E. P., R. Fullington, and L. Pratt. 1972.

Molluscan records from West Texas. Sterkiana 46: 6-10.

Pilsbry. H. A. 1905. Mollusca of the southwestern states. I:

Umcoptidae; Helicidae of Arizona and New Mexico. Proc.

Ac(id. Nat^ Sci. Ph iM.elph la 57: 257.

Pilsbry, H. A. 19.36. TTie eastern limit of Simtrrella. The

Nautilus 49(4): 109-110.

THE COMMENSAL CLAM, PARAMYA SUBOVATA

(BIVALVIA: MYIDAE) AND THALASSEMA HARTMANI

(ECHUROIDEA) OFF GALVESTON, TEXAS

Clyde A. Henry

Texas A&M Marine Laboratory

Building 311, Fort Crockett

Galveston, Texas 77550

Studies of macrobenthic assemblages offshore

Galveston, Texas, have revealed the presence of

the commensal bivalve, Paramya subovata

(Conrad, 1845). The highest concentrations of P.

subovata were found in May 1975 in the

Bolivar Roads entrance channel (13.5 m depth)

at 29° 19' 15" N. Lat. and 94° 38' 42" W. L:)ng.

A total of 242 living specimens, ranging in

length from 1.5 to 6 mm, were collected at this

site in five replicate spade corer samples. The

average calculated abundance was 745/m^ The

specimens agree with the description in Abbott

(1974, p. 537, Fig. 5989).

Jenner and McCrary (1970) reported

Paramya subovaia to be commensal specific

with the echiuroid worm, Thalassema hartmani

Fisher, 1947. T. hartmani has also been found

during the present study. At the Bolivar Roads

entrance channel site in May, a total of 261 in-

dividuals of T. hartmani were collected with an

average calculated abundance of 805/m^. Though

direct observations of the commensalistic

74 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

behavior of Paramya aubvvata were not made,

this non-leptonid bivalve has rarely been found

during the present studies in the absent of T.

hartmani.

Ladd (1951) and Ladd, et al. (1957) reported

dead specimens of Fnrnmya subnvata from the

Lydia Ann Channel in the vicinity of Aransas

Pass, Texas. As far as I am able to ascertain,

this is the first report of the occurrence of liv-

ing specimens of Paramya mibovata from Texas,

other than a beach-stranded specimen found

alive after a hurricane on Galveston West

Beach (Ode' and Speers, 1970). Thalassema hart-

mani is also previously unreported from Texas

coastal waters. I would like to thank Dr. R.

Tucker Abbott who mnfirmed the identification

of Paramya subovata (Del. Mus. Nat. Hist. no.

102595) and encouraged the development of this

report. This research was supported by Contract

No. IX) A RES DAC W64-7.5-()070 from the

Waterways Experiment Station, U. S. Army

Corps of Engineers."

LITERATURE CITED

.Abbott. R. T. 1974. American Seashetls. Second Edition, Van

NfKtrand Reinhold Co.. N.Y.. 6&3 p.

•Jenner. C. E. and A. B McC"rar>'- 1970. f\iramya aubovata,

a OTmmensal with the echiuroid Thalassema hartmani

Ann. Kept. Amer. Mai. Union. 1969. p 42.

I..;idd. H. S. 19.51. Brackish-water and marine assemblages of

the Texas Coast, with special reference to mollusks.

hibls. hist. Mar. Sci.. Umii Tmus. 2(1): 129-163.

Ladd. H. S., J. W. Hedgpeth, and R. Post. 19.57. En-

vironments and facies of existing bays on the central

Texas mast. In H. S. Ladd (ed.) Treatise on Marine

Ecology and Paleoecology. Vol. IL Paleoecology (leol. Soc.

r/Mmrr.Wem. 67, .599-639.

Ode'. H. and A. B. Speers. 1971). Notes concerning Texas

beach shells. 71'j-as Omchalugist 6(8): 83.

THE OCCURRENCE OF THE DATE MUSSEL, LITHOPHAGA BISULCATA

(MYTILIDAE), IN LIVING OYSTERS

OFF GALVESTON, TEXAS

John Ogle

(College of Marine Science

Texas A&M University

Galveston, Texas 77550

ABSTRACT

The date mussel, Lithophaga bisulcata, was found boring live oysters

Crassostrea virginica and Ostrea equestris at three petroleum platforms off

Galveston, Texas. A specimen of Lithophaga aristata found boriny into Ostrea

equestris is reported from Galveston.

In the course of conducting survival and

growth studies of commercial oysters

(Crassostrea mrginka Gmelin, 1791) at an off-

shore oil platform in the Northwest Gulf of

Mexico, it was noted that the oysters had been

burrowed by the date mussel Lithophaga

bisulcata (Orbigny, 1842). Experiments during

the past 2 years (1973-1974) were undertaken to

determine the feasibility of culturing oysters off-

shore in the Gulf of Mexico, utilizing

petroleum platforms for suspension culture.

These experiments, under the direction of Dr. S.

M. Ray', have utilized platform B of the Atlan-

' Head of M(K)dy College of Marine Science.

tic Richfield Company located 8 miles offshore

from High Island, Texas, east of Houston in ap-

proximately 10 m of water. The salinity varies

from 23 to 31 ppt over the year with an

average of 26 ppt. Temperature varies from 14°

to 29°C with a yearly average of 22°C. Mussels

were first noted during June 1974 in oysters

that had been suspended at the platform for 17

months. Ten oyster shells were carefully broken

apart and the number of mussels determined

(Table 1) on three different occasions.

Shell boring pholad clams identified as

Diplothyra .'imithi Tryon, 1862 were also found

in the oysters, two examined in June, five in

Vol. 90 (2)

THE NAUTILUS

75

TABLE 1. Intensity of mussel infestntivm in C. virginica.

Size of mussels (mmj

A l<erage oyster No. of mussels

Date size (vimj fH-r oyster Average Range

24

21

13

7

6

12

2-12

2-19

4-21

September and three in December of 1974. The

pholad borers were all from oysters suspended

in the upper 4 m of water. The boring mussels

were found in oysters suspended throughout the

water column.

No borers were noted during the 16 months

prior to June 1974 that oysters were suspended

offshore. It is suggested that both species of

borers settled during the summer of 1974. Bur-

rows of L. bisulcata were found in all parts of

the oyster shell as indicated by the radiograph

(Figure 1). The greatest number of mussels was

found anterad, close to the umbo, possibly due

to the greater thickness of the shell in this

area. In some cases the burrows penetrated into

the interior cavity of the shell. Several oysters

were actively depositing shell material in

response to the boring activity of the mussels

(Figure 2).

In November 1974, oysters occurring nat-

urally on oil platforms were collected utilizing

SCUBA. Both Ostrea equestris Say, 1834 and C.

virginica were collected at depths of 6-12 m

from a platform 12 miles south (173°) of the

Galveston lighthouse. No date mussels were

found, but burrows were observed in both speci-

mens of C. virginica collected. Ostrea equestris,

the only oyster species observed on another oil

platform 29 miles south (173 ) of the Galveston

lighthouse occurred in the water from 12 to 21

m. Eleven 0. equestris examined were infested

with an average of three to five L. bisulcata. In

addition, one specimen of Lithophaga aristata

(Dillwyn, 1817) 24 mm long was found.

Ode' and Speers (1970) report L. bisulcata

from old oyster valves at Port Aransas, Texas

and less commonly at Galveston. They report L.

aristata from Port Aransas and Port Isabel,

Texas, in rocks. The author is unaware of any

account of L. bisulcata burrowing into living

oysters. Turner and Boss (1962) report this

species as burrowing into living corals and into

"living shells such as Strombus" (p. 112). Both

C. virginica and 0. equestris were found U) be

burrowed by L. bisulcata in this study. The

species L. aristata has been reported to burrow

into Ostrea as well as a variety of other shells

(Turner and Boss, 1962) including the shell

plates of a chiton (Bullock and Boss, 1971).

These findings thus represent a new pest of

FIG. 1. Radiograph of oyster shell (actual size) shoumg

location and position of infesting musseb L. bisulcata.

FIG. 2 Photograph showing blisters on interior of shell

due to infestation by the mussel L. bisulcata (white rec-

tangle represents one cm).

76 THE NAUTILUS

April 3(3, 1976

Vol. 90 (2)

the Virgfinia oyster (Craxsostrea virginica) that

will be of concern to persons attempting to

culture oysters commercially in offshore waters

of the Gulf of Mexico.

ACKNOWLEDGMENTS

Appreciation is expressed to Captain J.

Roberts for the use of his boat Starfish, to his

son Mr. J. Rf)berts for Captaining the vessel,

and to Mr. T. Bullington and Mr. D.

McLaughlin for assistance in data collection.

Drs. D. V. Aldrich and W. J. Wardle reviewed

the manuscript and offered many helpful sug-

gestions and constructive criticism. Appreciation

is also expressed to the people at Public Health

Department in Galveston for doing the X-ray

and to Mr. J. Kelsey for aid in the darkroom.

Voucher specimens are deposited in the

Delaware Museum of Natural History, no.

106621.

LITERATURE CITED

Bullork. R. C, and K. J. Bok.s. 1971. Lithnphaga aristala in

the shell plates of Chitons (Mollu-sca). BrvviKi-a. Miis.

Comi). ZiiiiL No. 369, 10 p.

Ode. H.. and A. B. Speers. 1970. Notes concerning Te.xas

beach shells. Tex. Gmchot. 6(6): 59.

Turner, R. D.. and K. J. Boss. 1962. The genus Lilhophaga

in the Western Atlantic. JoAn,s(mia 4: 81-116.

REPRODUCTIVE HABITS OF F^OUR POPULATIONS OF

MUSCULIUM SECURIS (BIVALVIA: SPHAERIIDAE)

NEAR OTTAWA, CANADA'

G. L. Mackie,^ S. U. Qadri

and

A. H. Clarke

Biology Department

University of Ottawa

Ottawa, Ontario, Canada

National Museum of Natural Sciences

National Museums of Canada

Ottawa, Ontario, Canada

ABSTRACT

Comparative reproductive habits of populations of Musculium securis (Prime)

in two temporary forest ponds, a river and a permanent pond near Ottawa,

Canada were determined fivm .samples collected seasonally for one to three

years, and from laboratory and field experiments. Gametogenesis is most active

during the summer months. Spermatogenesis and oogenesis usually occur

simultaneously although protogyny is often apparent. Four to ten brood sacs

per inner gill are produced but only two to four sacs usually mature. Only 31

to 63% of the larvae in each brood sac are viable from the fetal stage of

development. The average litter size produced varies from 2.1 to i.8 indiindiials

per parent. Intrapopulation variations in reproduction are moye pronounced in

temporary than in permanent aquatic habitats. Interpopulation transplants of

M. securis indicate that reproductive habits may be adoptively modified.

The present study was planned to show the

extent of intrapopulation and interpopulation

variations in several reproductive aspects of

Musculium securis. The reproductive aspects ex-

amined were seasonal gonad activities, number

of brood sacs and larvae per sac (brood size).

' This contribution summarizes a portion of a thesis sub-

mitted by the senior author in partial fulfilment of the re-

quirements for the Ph.D. degree. University of CXtawa, 1973.

' Present address: Department of Zoology, University of

Guelph. Guelph, Ontario, Canada.

and the number and sizes of litters produced.

Four populations of M. securis were examined,

two from temporary forest ponds, one from a

river, and another from a permanent pond.

To distinguish between species of Musculium

and Sphaerium, van Cleave et al. (1947) have

given data to indicate that Musculium species

might have larger brood sizes than Sphaerium

species. Herrington (1962) suggested a need for

data on more species before evaluating the

significance of differential fecundities. Gale

(1969) suggested the use of standardized pro-

Vol. 90 (2)

THE NAUTILUS

77

cedures and the analysis of seasonal field col-

lections to show the extent of intraspecific

variations before evaluating the diagnostic value

of differential reproduction.

STUDY AREAS

Detailed descriptions of the study areas have

been given in Mackie (1973). Briefly, the two

temporary ponds, called Carp Pond and Greely

Pond, are located at Carp and Greely, Ontario,

and are situated in deciduous forests. The domi-

nant tree species at the ponds are white elm,

(Ulmus americana), willows (Sdix spp.), red

maple (Acer rubrimi). and trembling aspen

(Popuhis tremulflides). Carp Pond covers an

area of approximately 15,000 m^ with a maxi-

mum depth of 1 m and Greely Pond, 90,000 m^

with a maximum depth of 0.8 m. Miisculium

seciiris is the most common macroinvertebrate

in Carp Pond but Sphaerium (Mcidentale is ap-

proximately twice as numerous as M. seciiris

in Greely Pond. Both ponds are usually dry

from August to November. The mean summer

temperatures {18°C) of the ponds are usually

reached near mid-May.

The permanent aquatic habitats are located

in Britannia Bay of the Ottawa River near Ot-

tawa and at Lac Bourgeois in the Gatineau

Hills near Hull, Quebec. Fifteen species of

sphaeriids are present in Britannia Bay where

M. securis is the dominant species in the mud

of the 3-4 m depths (Mackie and Qadri, 1973).

Lac Bourgeois, with an area of approximately

90,000 m^ appears to contain only one sphaeriid,

M. fteciiris. which attains its largest densities on

the east shore under the shade of several small

willow trees. The mean summer temperatures

(18°C) of Britannia Bay is reached in mid -June

and of Lac Bourgeois in early June. Only

Britannia Bay contains fish; catfish (Ictalurus

punciatus). walleye (Stizostedion mtreum). and

pike (Esox lucius) are among the common fish

species. Seasonal fluctuations in several physical

and chemical characters of the water in each

habitat have been given by Mackie (1973).

MATERULS AND METHODS

The reproductive habits of each population

examined were seasonal gonad activities,

numbers of brood sacs and larvae per sac

(brood size), and numbers and sizes of litters

produced. These aspects were determined from

seasonal field collections and from adults main-

tained in the field and in the laboratory.

Seasonal Field Collections— From May 1970

to May 1973, 50-100 clams were collected twice

a month in the summer and once a month in

the winter from Carp Pond and Britannia Bay.

Greely Pond and Lac Bourgeois were visited

monthly for one year.

Random quantitative samples were taken

from Britannia Bay with a standard Ekman

grab (15 x 15 cm, with screen on top) and

qualitative samples from the remaining habitats

with an ordinary domestic sieve. The sizes of

the samples needed to show differences between

means of litter sizes at P = 0.05 were deter-

mined from the sample size formula of Simpson

et al. (1960, p. 196). The specific dates of collec-

tions and the sample sizes may be found in

Mackie (1973).

All clams used for reproductive studies were

preserved immediately in 70% ethanol. Since

some clams often prematurely aborted their

young, individuals longer than approximately 3

mm were isolated and put into vials containing

70% ethanol. Clams to be used for histological

examination were first narcotized in 10%

sodium nembutal (van der Schalie, 1963), fixed

in Bouin's fluid, and then preserved in 70%

ethanol. For each clam in the seasonal field col-

lections, lengths and heights were measured to

two decimal places in millimeters wnth a Preci-

sion Tools and Instruments Co. Ltd. microscope

micrometer, model 14.

Seasonal gonad activities were determined

from stained sections of gonads from 4 or 5 in-

dividuals of most field collections. Only

specimens prepared for histological examination

were used. Tlie shells of parents and extra-

marsupial larvae were removed by hand. After

dehydrating, clearing and embedding in paraf-

fin, the soft parts were sectioned to a thickness

of 8 microns. Sections were stained with Harris'

haematoxylin and oounterstained in alcoholic

eosin.

The numbers of brood sacs and their brood

sizes were determined for both the left and

right inner demibranchs. Usually the embryos

were so small that their numbers could not be

determined accurately. Therefore, data were

78 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

recorded for only fetal, prodissoconch, and

extra -marsupial larvae. Tlie lengths of all

shelled larvae were also recorded. Since 99% of

the extra -marsupial larvae were viable (as

shown from growth studies), their numbers

were taken as a valid measure of litter sizes

produced by M. securis. Note that the brood

size is the number of larvae per brood sac

while the litter size produced is only the

number of extra-marsupial larvae per litter or

the number of young bom at one birth.

The numbers of litters produced by parents

were determined by back-calculation of brood

sacs; this technique has been described by

Mackie, Qadri and Clarke (1974a). Only parents

which had completed growth were used to

determine the numbers of litters produced.

Parents that had completed growth could

usually be identified by the formation of a

black deposit on the margin of their shells.

Maintenance of M securis in the laboratory

and field— Reproductive studies on adults main-

tained in the laboratory and field were done to

complement those in seasonal field collections.

Growth tubes, prepared from 45 mm diam. x 70

mm ht. plastic vials (Mackie, 1973), were used

to maintain adults in the field. Racks, made

from 1 cm thick plexiglass sheet, were con-

structed to hold twenty growth tubes.

A rack of twenty tubes was put into each of

Carp Pond, Britannia Bay, and Lac Bourgeois

on May 9, 1972 (Greely Pond was not in-

vestigated because it was first examined on

June 6, 1972). Each growth tube contained one

newborn M. securis and substrate (1 cm deep)

from the habitat in which the tube was placed.

The lengths of adults were measured at approx-

imately two week intervals until their deaths.

Newborns were counted and removed as they

appeared in each tube. The numbers of litters

produced by each parent were also noted.

Interpopulation transplants were performed

to determine if the sizes and numbers of litters

produced by M. securis adults were environmen-

tally or genetically controlled. Newborn M

securis from each habitat were isolated and

maintained in growth tubes in all habitats (ex-

cept Greely Pond) including its own. Lengths of

clams were measured at approximately two

week intervals until their deaths. The litter

sizes and the numbers of litters produced were

also recorded.

Adults from Cai:p Pond, Britannia Bay, and

Lac Bourgeois were also maintained in the

laboratory. Since M. securis would grow only in

the presence of tree foliage, only substrate and

leaves from Carp Pond were used. "Pyrex"

dishes 100 mm diam. x 50 mm ht. were used as

growth dishes. Five M. securis newl»ms from

each habitat were put into each of three dishes.

Thiree replicates were made of each dish con-

taining 5 M seairis, 50 g of air dry Carp Pond

soil, 2 g of air dry white elm leaves, and

chlorine-free tap water. The lengths of adults

were recorded at frequent intervals and the

total number of young produced in each dish

was recorded.

A student's t test. (Simpson et ai. 1960, p.

176) was used to determine significant dif-

ferences between population means at P = 0.05.

RESULTS AND DISCUSSION

Seasonal Gonad Activities. The gonads of

newborns are small and often difficult to locate.

Primary oocytes are often seen in newborns

that have estivated and/or hibernated in Carp

Pond and Greely Pond but neither oogenesis

nor spermatogenesis is strongly apparent (Fig.

1-1) when serial sections of the gonads are ex-

amined. Gametogenesis does not appear to

begin until growth of adults ensues in the

spring. At this time the ovary appears to be in

further stages of development than the testis

(Fig. 1-2). Throughout May, June, and early

July, both fully developed ova and sperms are

present but there is no evidence of increased

gonad activity with time (Fig. 1, -3, A, -5, -6).

Spermatogonia and spermatocytes are readily

visible and usually fill the entire follicular cav-

ity. It is not until late July that sper-

matogenic activity appears to be maximum

(Fig. 1-7). In late-July -specimens the sper-

matozoa are usually found in the central lumen

of the testicular follicles (Fig. 1-7) where the

tails of the sperms are clearly visible (Fig. 1-8).

Frequently the testis is so large in these late

July specimens that the ovary cannot be

located.

In specimens over 4 mm in length collected

between November and April from Lac

Vol. 90 (2)

THE NAUTILUS

79

1

4'

4^ * .^ i J

'''f?

"v*!'

#f

.t

%*

y

\

%.

'4f.

^

.» M^^

*.^

%%

FIG. 1. Photomicrographs of seasonal gonad activity in

Musculium securis in Carp Pmtd. DO develivping (Kigonia. I

intestine. K) primary oocytes. ST spermatozoa, STT tails of

spermatozoa, SY spermatocytes.

1. October 10. 1970. Length of parent 1.70 mm. 380X.

2. May 20. 1971. Length of parent S.S5 mm. 380X.

Bourgeois, the testicular follicles show evidence

of a decided reduction in spermatogenesis and

primary oocytes are usually absent in the

ovaries. The central lumens of the ovaries and

testis are devoid of gametes so that

gametogenesis probably does not occur during

the winter months.

Although there are variations, gametogenesis

is first apparent in adults of lengths 2.00-2.50

mm. The testis greatly dwarfs the ovary in

adults larger than 5.50 mm. On the basis of the

earliest appearance of primary sacs, eggs are

first fertilized in adults of lengths of 2.00-2.50

mm.

Numbers of Brood Sacs and Brood Sizes.

Demibranchs within a parent usually contain

the same number of brood sacs. A maximum of

three brood sacs per demibranch (i.e. six brood

sacs per gill) are usually found but four brood

3. May 30. 1971. Length of parent 3. 76 mm. 380X.

I June U. 1971. Length of parent 165 mm. 380X.

5. .June 28 1971. Length of parent 5.22 mm. 380X.

6. July 12 1971. Length of parent 5.68 mm. 380X.

7. July 26, 1971. Length of parent 5. 75 mm. 95X.

8 Same as no. 7 but 380X.

sacs also occur, although very rarely. The total

number of brood sacs per gill varies with the

size and age of the parent (Fig. 2).

During the summers of 1970 and 1971, only

parents longer than 4.00-4.50 mm in the Carp

Pond population contained 6 brood sacs (Fig.

2a). By late June extra-marsupial larvae are

present but 6 brood sacs also occur indicating

that a total of 8 brood sacs (i.e. 2 primary, 2

secondary, and 4 tertiary) are produced. This is

probably the average maximum number since

only four brood sacs per gill (i.e. 2 secondary,

and 2 tertiary) are found in parents taken at

the end of July. In 1972 when the pond did not

dry up, the same phenomena occurred (as ex-

emplified by results from Greely Pond, Fig. 2b)

and new sacs were not produced in later sum-

mer. Therefore, the extended aquatic season has

little effect on the total number of brood sacs

80 THE NAUTILUS

April 30. 1976

Vol. 90 (2)

2 4 6|2 4 c,\! A S\l 4 6|2 4 e|2 4 e{2 4 S

TOTAL NUMBER OF BROCD SACS

M10 I M20 1 M3C I J14 I J2e | J12 | J2S

DATES SAMPLES COLLECTED

2 4 G|2 4 6|2 4 6|2 4 S|2 4 G|2 4 S|

TOTAL nUMBER Ot BROOD SACS

M28 I Jll 1 J24 I J1S 1 J29 I All I

DATES SAMPLES COLLECTED

fee

(/)

UJ

SB

<

u

2 4 6|2 4 6[2 4 6|2 4 e|2 4 e|2 4 6|2 4 S

TOTAL NUMBER OF BROOD SACS

J6 I J18 I J7 I J23 I A6 I A19 | S2

DATES SAMPLES COLLECTED

FIG. 2. Total number of brood aaat per inner gill in parents

collected between (a) May 10 and July 26, 1971 from Carp

Pond, (b) June 6 and September 2. 1972 from Greely Pond.

(c) May 28 and August _ 11. 1971 from Britannia Bay. (d)

May 8 and September 20. 1972 from Lac Bourgeois. Each

produced although more brood sacs mature (i.e.

4 brood sacs per gill remained in 1970 and 1971

adults but 2 remained in the 1972 adults).

Six brood sacs are uncommon in individuals

from the Britannia Bay population and are

found only in July (Fig. 2c). There appear to be

no major differences in the total numbers of

brood sacs between 1970, 1971 and 1972 popula-

tions of Britannia Bay. Usually a total of six

brofxl sacs are produced but only two brocxl

sacs mature and four remain immature at the

end of the summer. Clams of lengths 2.00-3.50

mm represent slow-growing adults (Mackie,

Qadri, and ('larke, 1974b) which usually pro-

duce a total of only four brood sacs (Fig. 2c).

24S|246|246|246 24G|24S

TOTAL NUMBER OF BROOD SACS

M8 |'M2eI J13 I J6 I AS I S20

DATES SAMPLES COLLECTED

size class represents a 0.1f9 mm increment in shell length

(i.e. 1 = IH).J,9 mm.. 2 = 0.50-0.99 mm. .1 = 1.00-H9 mm.

.... 12 = 5..'}0-5.99 mm. 13 - lengths greater than 6.00

mm). Rni'h interval (m the ordinate aris als(i represents

100%.

Six brood sacs per gill are most common in

adults longer than 4.50 mm in Lac Bourgeois

(Fig. 2d). At least 8 brood sacs are produced by

many parents since one litter of e.xtra-

marsupial larvae is released and 6 brood sacs

still remain by mid-September. Some parents

celease another litter of extra-marsupial larvae

in the fall and many still have 6 brood sacs per

gill. Therefore, some parents of Lac Bourgeois

produce as many as 10 brood sacs per gill.

The number of larvae in brood sacs of

parents from each population are given in

Table 1. Primary sacs are not included because

the embryos were too small to be counted ac-

curately. The total number of larvae increases

Vol. 90 (2)

THE NAUTILUS

81

TABLE 1. Sizt^ (if lutein in nmrsntpial chamber and hruad sizes of Musculium securis in four habitats for each year of

collection. Only parents in which all larvae were present and from which no extra-marsupial larvae had been released were

examined.

' Mean litter or brood size.

' Number of specimens examined.

'Standard deviation of the mean.

TABLE 2. Percentage of Musculium securis parents producing mie, two. and three liters in each of four habitats for each

year of collection. The percentages are based o'n back-calculation of brood sacs in parents that had completed growth.

° Number of specimens examined.

with age of the parent indicating that the

generative performance increases with age.

Numbers of Litters Produced. Table 2 gives

the percentages of adults that produced one,

two, or three litters in each population for each

year of study. A maximum of three litters were

produced by a single parent. Variations in the

numbers of litters produced within and among

populations are discussed later in this paper.

One litter was usually produced in the

growth tubes placed in Carp Pond, Britannia

Bay, and Lac Bourgeois and in the laboratory

growth dishes (Table 3). A maximum number of

three litters was produced in all maintenance

studies. The results were obtained by noting the

presence or absence of newborns in the growth

containers at approximately two week intervals.

Analyses of parents from seasonal field collec-

tions show that in a few instances two litters

of extra-marsupial larvae occur together, par-

ticularly when the litter sizes are small.

Therefore, it is possible that two litters may

have been produced within two weeks in the

growth containers. If this occurred then a maxi-

mum of six litters was produced. However,

studies on the numbers of brood sacs produced

show that usually four sacs, and rarely five, are

formed in each inner demibranch. Therefore,

the maximum number of litters most likely pro-

duced in the growth containers was four.

Sizes of Litters Produced. Since only extra-

marsupial larvae are released, their numbers

represent the sizes of litters produced. Table 4

gives the sizes of the first litters in all popula-

tions for each year of study and of second lit-

ters in populations of which at least 35% of the

parents produced two litters. The sizes of the

first and second litters of prodissoconch and

fetal larvae in sequential parents are also in-

cluded in Table 4. Sequential parents are those

parents that represent a stage in the sequential

development of each litter of extra-marsupial

larvae. That is, the sizes of the first and second

litters of prodissoconch and fetal larvae that

82 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

TABLE 3. Numbers and sizes of Utters prodveed by Musculium secuiis adtdts maintained in growth containers in three

habitats and in the Utburatirry. Means sidescored by the same line we nut significantly different at P = 0.05.

Papulatvm* trangptanled into:

L/ic Bnurgcuix fntm:

Lac Bourgeois (control, N = 18)"

Carp Pond (N = 16)

Britannia Bay (N = 15)

Carp Pond from.

Lac Bourgeois (N = 16)

Carp Pond (Control. N = 17)

Britannia Bay (N = 14)

Britannia Bay from:

Lac Bouritjeois (N = 16)

Carp Pond (N = 17)

Britannia Bay (Control, N

18)

Adults maintained in the

Laboralorj'

Carp Pond

Lac Bourgeois

Britannia Bav

"Twenty specimens were put into eac)i habitat but only N number survived.

'Calculated as (Size of first litter X proportion of parents pnjducing only one litter) + (Total number of young born X

proportion of parents producing two litters).

■ Of the adults that survived, one or two produced young.

represent the first and second litters of extra-

marsupial larvae were counted in parents from

three successive field collections.

The results (Table 4) show that the sizes of

the first and second litters of each larval stage

are similar (P > 0.05) but there are usually

significantly larger numbers (P < 0.01) of fetal

larvae than of prodissoconch larvae which in

turn are numerically larger (P < 0.01) than e.x-

tra-marsupial larvae. Clearly, the results in-

population consistently produced fewer (P <

tion often differed (P < 0.05) among habitats,

the extra-marsupial stage.

Table 3 indicates that there is some genetic

TOntrol of litter size since the Brittania Bay

population consistently produced fewer (P <

0.05) young in all transplants than did other

populations of the same transplants. However,

there also appears to be some environmental

control of litter size since the tt)tal number of

young produced by parents of any one popula-

tion often differed (P < 0.05) among habitats.

Intraspecific variations in reproductive

habits of Musculium securis. There is some

variation in the seasonal gonad activities be-

tween slow- and fast-growing adults (Mackie,

Qadri, and Clarke, 1974b) in Britannia Bay. In

slow-growing adults gametogenesis is first ap-

parent in length classes 2.00-2.50 mm but in

fast -growing adults gametogenesis is not ap-

jiarent until clams are of lengths 3.00-3.50 mm.

Cametogenesis and fertilization appear to

continue until the death of the individual in all

populations but is most active in the summer

months. Similar observations have been reported

by Okada (1935) for M. japonicum. Okada (op.

cit.) also noted that spermatogenesis is most ac-

tive in clams measuring 3-7 mm in length and

(M)genesis in those measuring more than 8 mm;

protandrous maturation of M. juponwum is

therefore suggested. The results of the present

study indicate that ova and sperm mature at

approximately the same time although primary

oocytes (ova lying free in the ovarian cavity)

are often present before spermatids; therefore.

Vol. 90 (2)

THE NAUTILUS

83

TABLE 4. Sizes of fii'st and second litters per (fill and the percent viability of larvae in seqttential parents (defined in

text) of Musculium securis in four habitats for each year of adlection.

Second larval litters

In sequential parents

' Mean litter or brood size.

' Number of specimens examined.

'Standard deviation of the mean.

'% viability = (extra -marsupial larvae, tetal larvae) X

100.

protogyny may occur in some individuals.

Simultaneous maturation of gametes also seems

to occur in Sphaerium simile (Zumoff, 1973)

and M. paiiumeium (Thomas, 1959).

Intraspecific variations in seasonal gonad ac-

tivity is also present in other sphaeriids. Foster

(1932) suggests that maximum size adults of S

striatinum are sterile and reproduction occurs

in the winter months; Avolizi's (1971) data in-

dicate that reproduction in this species occurs

until the death of the animal with peak

reproduction in spring and fall but Monk (1928)

found that reproduction of S. striatinum is at a

peak during the summer months.

There is very little intrapopulation variation

in the total number of brood sacs produced per

parent from one year to the next. However, in-

terpopulation variations in brood sac production

are present. Individuals in Britannia Bay usu-

ally produce a total of six brood sacs while

those in other papulations usually produce

eight, and occasionally ten (Lac Bourgeois),

brood sacs. Of these totals, only two to four (oc-

casionally six) brood sacs mature. Therefore, the

potential total number of litters (six to ten) is

probably rarely achieved, although Heard (1974)

suggests that M. securis can "produce several

litters over a life span of several years".

A significantly larger number (P < 0.05) of

extra -marsupial larvae occurred in 1971 than in

1970 or 1972 in Carp Pond, Britannia Bay, and

Lac Bourgeois. There are no significant dif-

ferences (P > 0.05) in the numbers of pro-

dissoconch larvae nor of fetal larvae between

the 1970, 1971 and 1972 populations of Carp

Pond and Britannia Bay nor between 1971 and

1972 populations of Lac Bourgeois. The numbers

of each larval stage in Greely Pond adults are

similar to those in Carp Pond adults in 1972.

Smaller numbers (P < 0.05) of prodissoconch lar-

vae and of fetal larvae are produced in the

Britannia Bay population than in other

populations. Lac Bourgeois parents produced

larger (P < 0.05) numbers of extra-marsupial lar-

vae in 1972 than did other populations in the

same year and similar numbers (P < 0.05) of

prodissoconch and of fetal larvae as Carp Pond

and Greely Pond in the last two years of study.

84 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

Significantly more (P < 0.(X)5) parents pro-

duced two litters in 1972 than in previous

years of study in Carp Pond (Table 2). The

1972 increase is attributable to the extended

aquatic season since the data was obtained

from parents sampled in August and Septemter

when the pond was usually dry. The data for

1970 and 1971 were obtained from parents col-

lected at the end of July, just prior to the

disappearance of water from the pond. Parents

of Carp and Greely Ponds produced the same

proportions of one and two litters in 1972. A

larger proportion (P < 0.005) of parents produce

one litter in Britannia Bay than in other

habitats. No differences are obsei-ved in the

proportion of parents producing one and two

litters in Lac Bourgeois, Carp Pond, and Greely

Pond although a small percentage of parents

produce three litters in Lac Bourgeois. The ex-

tended aquatic season had no apparent affect

on the numbers of litters produced by in-

dividuals in the Britannia Bay and Lac

Bourgeois populations.

The results from the transplant studies (Table

3), suggest that the Britannia Bay population

may be adaptively modified with respect to the

number of litters produced. That is, with two to

four weeks lag in rate of temperature increase

in Britannia Bay (Mackie, 1973), the population

has less time than other populations to produce

additional litters. Hence, there is greater sur-

vival value to select for one litter than for

several litters of which only one can be pro-

duced.

Gale (1969) proposes that more discretion is

needed in comparing the numbers of embryos

in various species since differences may reflect

seasonal or parental size class variations; also

purported differences between species may be

due to differences in procedures used by various

investigators. The present study indicates that

brood sizes of M. necuris vary greatly within

and among habitats, primarily because of dif-

ferences in larval mortalities. However, there

appears to be less variation in the brood sizes

of secondary sacs within and among populations

with similar habitats. Therefore, the numbers of

fetal larvae alone (and probably embryos) ap-

pear to be more valid measurements for deter-

mining differential fecundities among species

within similar habitats than are numbers of

extra -marsupial or prodissoconch larvae.

The data (Table 3 & 4) also indicate that

both intrapopulation and interpopulation varia-

tions in litter sizes are present. Within the

Carp Pond, Britannia Bay, and I>ac Bourgeois

populations, the sizes of litters released are

significantly larger in the second year of study

than in the first. These higher values may in-

dicate the response of M. securis to replace

those individuals that had been removed for life

history analyses by the author in the previous

year of study. The removal of specimens by the

author are interpreted as representing a mor-

tality factor that is not normally present in the

populations. If this interpretation is correct, M.

securis compensated for the high mortality by

producing large litters in the following year.

This appears to be achieved, not by producing

more eggs (since the total number of fetal lar-

vae per* parent remained relatively constant),

but by maintaining a greater survival rate

(reflected in % viability. Table 4) of larvae

already produced. In this context, the sampling

efforts of the authors apparently had little

ultimate effect on the litter sizes produced

since the litter sizes in the third year of study

are not significantly different from those in the

first year (Table 4). This is a valid interpreta-

tion if the large amount of rainfall in 1972 did

not cause reductions in the litter sizes pro-

duced.

The viability of M. securis larvae from the

fetal stage of development ranges from 37% to

63% in the first litter and 31% to 52% in the

second litter, depending on the year of study

and the habitat. Since the number of embryos

probably exceeds the number of fetal laiTae, the

percent viability of larvae from point of fer-

tilization of the egg is probably smaller. The

data (Table 4) also indicate that M. seairis

produces a certain number of eggs, this number

being genetically fixed. This is suggested from

the similar numbers of fetal larvae (approx-

imately 7.0) of the first litters in Carp Pond,

Greely Pond and Lac Bourgeois. The Britannia

Bay population produces significantly smaller

numbers (P < 0.01) of fetal larvae per sec-

ondary brood sacs than other populations. This

implies that either a high mortality of embryos

Vol. 90 (2)

THE NAUTILUS

85

occurs in the Britannia Bay population or that

the population is genetically distinct with

respect to egg production and indicates that the

litter size can be modified adaptively. Support

for adaptive modification of litter size is seen

in the results from the transplant studies

(Table 3). The Britannia Bay population pro-

duced significantly smaller (P < 0.05) litter

sizes in all transplants than did other popula-

tions of similar transplants.

Avolizi (1971) has also studied larval

viabilities but presented his data in terms of

"embryonic mortality"; the maximum embryonic

mortalities of S. stnatinum and S. simile are

90% and 77-65%, respectively (i.e. larval

viabilities of 10% and 23-35%, respectively).

Avolizi (op. cit.) suggests that "the dying off of

younger stages contributes to the nutrition

of... embryos which survived". The litter sizes

of S stnatinum and S simile at birth range

from 1-2 for both species.

The annual ratio of selection of M. securis

(i.e. number of young bom annually per

average adult) varies widely within and among

populations. For example, the Carp Pond

population in 1970 and 1972 and the Greely

Pond population in 1972 had an annual ratio of

selection of ABOUT 5:1; this ratio increased to

about 7:1 in the 1971 Carp Pond population.

With only one litter, the Britannia Bay popula-

tion has a low annual ratio of selection of

about 2-3:1 while parents in Lac Bourgeois

have the highest annual ratio of selection (8:1).

Analyses of results obtained from seasonal

field collections and the maintenance of adults

in the field and laboratory (Table 3) indicate

that the annual ratio of selection is a function

of density dependent and independent factors.

This is also suggested from the results obtained

by Mackie's (1973) ecological studies on the ef-

fects of such factors as intraspecific and in-

terspecific competition, temperature, and pollu-

tion on the growth and reproduction of M.

securis. Similar conclusions are reported by

Avolizi (1971) for S. simile and S. striatinum.

Burky (1968) has demonstrated that the annual

ratio of selection of Ferrissia riindaris varies

from 35 : 1 in an eutrophic habitat to 8:1 in an

oligotrophic stream.

Heard (1974) describes five types of reproduc-

tive cycles in Sphaerium and Musculium. The

Type II cycle describes reproduction of M.

seruri.s in the Britannia Bay and Lac Bourgeois

populations where there are two or three

periods of fertilizations and births every year.

However, neither of the five cycles defined by

Heard (1974) describe reproduction of M. securis

in the Carp Pond and Greely Pond populations.

In conformity with Heard's (1974, Table 41)

criteria, the reproductive cycle of the latter two

populations can be described as having a life

span of approximately one year, semelparous

reproduction with one litter (or two litters in

one birth period) per year, rarely a fall and

winter incubation period, and only one birth

period (summer).

ACKNOWLEDGMENTS

This research was supported by the National

Research Council of Canada, Grant No. A 2386

awarded to S.U.Q. and by a Postdoctorate

Fellowship awarded to G.LH. by the National

Museums of Canada.

LITERATURE CITED

Avolizi, R. J. 1971. Biomass turnover in natural populations

of viviparous sphaeriid clams. PhD dissertation. Syracuse

Univ.. Syracuse. New York, 150 p.

Burk\'. A. J. 1968. Biomass turnover, energy balance and in-

terpopulation variation in the stream limpet, Ferrissia

riiidaiis (Say), with special reference to respiration,

growth, and fecundity. PhD dissertation, Syracuse Univer-

sity.

Foster. T. D. 1932. Observations on the life history of a

fingernail shell of the genus Sphaerium. J. Morph. 53:

473-497.

Gale, W. F. 1969. Bottom fauna of Pool 19, Mississippi

River with emphasis on the life history of the fingernail

clam, Sphaerium transversum. PhD dissertation, Iowa

State Univ.. Ames, Iowa 233 p.

Heard. W. H. 196.5. Comparative life histories of North

American pill clams (Sphaeriidae: Pisidium). Malacologia

t 381-411.

1974. Manuscript of "Comparative life histories of

fingernail clams (Sphaeriidae: Sphaerium and

Miisndium)" . MalacoUjgia 15: (In press).

Herrington, H. B. 1%2. .A revision of the Sphaeriidae of

North America (Mollusca: Pelecypoda). Misc. Publ. Mus.

Zool. Univ. Mich., No. 118, 1-74.

Mackie, G. L. 1973. Biology of Museuliym secm-is

(Pelecypoda: Sphaeriidae) in two temporary forest ponds,

a river, and a permanent pond near Ottawa. Canada.

PhD dissertation, Ottawa Univ., Ottawa. 17.5 p.

Mackie. G. L. and S. U. Qadri. 1973. Abundance and

distribution of Mollusca in an industralized portion of

86 THE NAUTILUS

April 30. 1976

Vol. 90 (2)

the Ottawa River near Ottawa-Hull, Canada. J. Fish. Res.

Ba. Canada 30: 167172.

Mackie, G. L, S. U. Qadri, and A. H. Clarke. 1974a.

Development of brood sacs in Mvsculiian securis

(Pelecypoda: Sphaeriidae). The Nautilus 88: 109-111.

19741. Intraspecific variations in growth, birth

periods, and longevity of four populations of Muscidium

securis (Pelecypoda: Sphaeriidae) near Ottawa. Canada.

Malariihigia: (In press).

Monk. G. R. 192& The anatomy and life-history of a

freshwater mollusk of the genus Sphaerium. J. Morph.

45: 473-503.

Okada. K. 1935. Some notes on Muscidiwn heterodon

(Pilsbry). a freshwater bivalve. III. Fertilization and

segmentation. Sci. Rpt. Tohoku Imp. Univ.. Ser. i. Biol.

10: 467-483.

Simpson. G. G., A. Roe. and C. R. Lewontin. Quantitative

ZtKiltyy. Harcourt, Brace and Co.. New York, 440 p.

Thomas. G. .1. 1959. Self-fertilization and production of

younginasphaeriidclam. TheNautilu.<t 72: 131-140.

van Cleave, H. J., A. G. Wright, and C. William Nixon.

1947. Preliminary observations on reproduction in the

molluscan genus Musculium. The Nautilius 61: 6-11.

van der Schalie, H. 1953. Nembutal as a relaxing agent for

mollusks./l»«. Midi Nat. .50: 511-512

Zumoff. C. H. 1973. The reproductive cycle of Sphaeriwri

simUe. Biol. Bull. 144: 212-228.

THE GENUS FONTIGENS FROM APPALACHIAN CAVES

(HYDROBUDAE: MESOGASTROPODA)

Leslie Hubricht

4026 a5th Street

Meridian, Mississippi 39.301

ABSTRACT

Fontigens holsingeri Hubricht from Hnnnan Cave, Randolph Co.. West

Virginia, and Fontigens turritella Hubricht from McClung Cave. Greenbrier Co..

West Virginia are described as new species. Additional geographical records are

given for Fontigens orolibas Hubricht. Fontigens aldrichi (Call & Beecherj.

Fontigens tartarea Hubricht. and Fontigens nickliniana (Lea).

Fontigens holsingeri new species

Fig. lA

Description: Shell small, conical, diameter

about 65% of height, thin, translucent, dull,

pale yellowish -horn; umbilicus open, about 0.1

mm. in diameter; nuclear whorl nearly flat,

later whorls regularly increasing in size, well

rounded with very deep sutures, each whorl

lightly appressed to the preceding whorl;

sculpture of numerous inconspicuous growth

lines; aperture ovate, vertical, may or may not

be appressed to the preceding whorl; lip thin,

sharp, with a very slight thickening within.

Operculum paucispiral, thin, of about 3.5

whorls, hyaline, the nucleus being located about

one-half way between the center and the lower

right margin. Animal unpigmented and blind,

verge unknown.

Height 1.7 mm., diameter 1.1 mm., aperture

height 0.6 mm., aperture width 0.5 mm., um-

bilicus diameter 0.1 mm., 4.5 whorls. Holotype.

Distribution: West Virginia: Randolph Co.:

stream in Harman Cave, 0.5 mile southwest of

Harman (Type locality) (J. R. Holsinger & D. C.

B

FK;. \.\. Fontigens holsingeri Hubricht. hotott/pe. Length.

1.7 mm.

FIG. IB. Fontigens turritella Hubricht. holotype. Length. 1.9

mm. Drawings courtesy Field Museum of Natural History.

Chicago, with thanks to Elizabeth Liebman for her skilled

efforts.

Vol. 90 (2)

THE NAUTILUS

87

Culver, colls.), holotype 170893 and paratypes

170392 Field Museum of Natural History, other

paratypes 42560 and 43635 collection of the

author; stream in Bazzle Cave, 1.0 mile south-

southeast of Harman (J. R. Holsinger & D. C.

Culver, colls.). Pocahontas Co.; stream in Pidd-

ling Pit Cave, 10 miles north-northeast of Mar-

lington (J. R. Holsinger, R. Baroody, & R.

SwenSvSon, colls.); stream in Marthas Cave, 0.9

miles southwest of Hillsboro (David Culver &

David Newson, colls.).

Remarks: Fontigens holsingeri is most closely

related to F. eryptica Hubricht; differing in be-

ing larger, with more rounded whorls, and a

more open umbilicus. Fontigens tartarea

Hubricht, which is found in the same area dif-

fers in its flatter whorls and shallower sutures.

Fontigens turritella new species

Fig. IB

Description: Shell small, conical, turreted,

diameter about 48% of height, thin, pale straw

colored, translucent, dull; nuclear whorl

depressed, giving the shell a truncated ap-

pearance, later whorls regularly increasing in

size, well rounded with deep sutures; sculpture

of very weak growth lines and spiral lines;

aperture ovate, vertical, lightly appressed to the

preceding whorl; lip thin, sharp, with a very

slight thickening within, not reflected in the

columellar region. Operculum paucispiral, thin,

hyaline, of about 2.5 whorls, the nucleus located

left of center. Animal unpigmented and blind.

Verge with three lobes, the upper lobe

slender, cylindrical, less than one-third the

length of the other two lobes, and attached

near the base of the center lobe; the center

lobe and the lower lobe are joined together

along most of their length, with only their tips

separate, they excede in length the diameter of

the shell; the center lobe contains the sper-

mathecal duct, the other lobes contain much

smaller ducts of unknown function.

Height 1.9 mm., diameter 0.9 mm., aperture

height 0.5 mm., aperture width 0.5 mm., 5.5

whorls. Holotype.

Distribution: West Virginia: Greenbrier Co.:

stream in McClungs Cave, 2 miles northeast of

Maxwelton (Type Locality) (John Rutherford;

Leslie Hubricht, colls.), holotype 170891 and

paratypes 170890 FMNH, other paratypes 38272

and 40694, collection of the author; stream in

The Hole Cave (Gibbs Eiitrance Section), 2

miles east of Frankford (J. R. Holsinger, D.

Culver, P. Starr, S. Peck, & D. Newson, colls.).

Remarks: Fontigens turritella differs from all

the species knovwi from Appalachian caves ex-

cept F. nickliniana (Lea) by its elongate shape,

its height exceeding twice the diameter. From

F nickliniana it differs in its verge, in its

smaller size, in its truncated spire, and more

slowly increasing whorls.

Fontigens aldrichi (Call & Beecher)

Pnhidina obhisa Lea. 1841. Proc. Amer. Phil. Soc. 2: 34.

(Not. P obtma Troschel. 1837).

BythinMa aldnchi Call & Beecher. 1886. Bull. Washburn

Coll. Lab. Nat. Hist. 1: 190-19i

Amnicola aldrichi aldrichi (Call & Beecher). Hubricht, L.

1940. Nautilus 53: 118-119.

Snails found in springs and caves from north-

western Virginia north to Maryland are not

distinguishable from snails found in the eastern

Ozarks of Missouri. The spring form with eyes

and dark gray pigment were collected at the

following localities: Virginia: Highland Co.:

spring, 0.7 mile southwest of Mustoe; spring, 1.3

miles north of Mustoe. Both of these springs

are in the headwaters of the Jackson River.

The blind unpigmented cave form was found

at the following localities: Virginia: Bath Co.:

stream in Butler Cave, 1 mile north of Bums-

ville (J. R. Holsinger, T. Vigour, & L. Vinzant,

colls.). Frederick Co.: stream in Ogdens Cave,

3.5 miles west-northwest of Middletown.

Maryland: Washington Co.: beneath stones,

large spring, 0.4 mile south of Little Heiskell

Quarry (F. Wayne Grimm, coll.).

It is probable that during the Pliocene, Fon-

tigens aldrichi lived in springs in the northern

United States but was forced south by the

Pleistocene glaciers. Because the kind of springs

in which it lived were covered over by till, it

was not able to move back into its old range

and has survived only in the Appalachians, the

eastern Ozarks, and if the type locality for

Paiudina obtusa is correct, in Ohio.

Fontigens orolibas Hubricht

Fontigens orolibas Hubricht. 1957. "Hie Nautilus 71: 9.

88 THE NAITILUS

April 30, 1976

Vol. 90 (2)

An unpigmented form of this species, which

may or may not have eyes, has been collected

in the following caves: Virginia: Warren Co.:

stream in Skyline Caverns, 2 miles south of

Front Royal. Giles Co.: stream in Smoke Hole

Cave, Newport (J. R. Holsinger & H. R. Steeves.

colls.): stream in Tawneys Cave, near Newrport;

stream in Stames Cave, 3.5 miles south-

southeast of Narrows (J. R. Holsinger & S.

Hetrick, colls.). Tazewell Co.: stream in Hugh

Young Cave, 1.5 miles southwest of Liberty Hill

(J. R. Holsinger, coll.).

Fontigens tartarea Hubricht

Fontigenstartann Hubricht. WWA Nautilas76: 140.

Since this species was described it has been

found living in the following caves: West

Virginia: Tucker Co.: stream in Harpers Cave,

5 miles southeast of Hendricks (J. R. Holsinger

6 D. C. Culver, colls.). Randolph Co.: stream in

Simmons-Mingo Cave, 1.5 miles southwest of

Mingo (R. B. Williams, coll.); stream in Bowden

Cave, 7 miles east of Elkins (J. R. Holsinger &

D. C. Culver, colls.). Monroe Co.: stream in In-

dian Draft Cave, a few miles south of Wayside

(J. R. Holsinger, D. C. Culver, & R. Baroody,

rolls.); stream in Rock Camp Cave, 1.6 miles

south of Rock Camp; stream in McClungs Cave,

Zenith.

Specimens from EJowden Cave are ven- small:

height 1.2 mm., diameter 0.7 mm., and are

probably the smallest freshwater snails known

from the eastern United States.

Fontigens nickliniana (Lea)

Palidina mcklinUma Lea. 1839. Trans. Amer. Phil S()c n

s. 6: 92.

Fimtiyens nickliniana (Lea). Pilsbrv. 1933. Nautilus 47:

12.

What appears to represent a blind, white,

cave form of this species has been collected at

the following localities: Went Virginia: Monroe

Co.: stream in Hunt Cave, near Sinks Grove (J.

R. Holsinger, coll.). Virginia: Lee Cx).: stream in

Gallohan Cave No. 1, 6.5 miles southeast of

Rose Hill (J. R. Holsinger, coll.); stream in

Spangler Cave, 3.5 miles west of Jonesville

(J. R. Holsinger, coll.); pool in Smiths Milk

Cave, 7 miles southeast of Rose Hill (.1. R.

Holsinger, D. C. Culver, colls.). The verge has

not been e.xamined from any of these lots. It is

very difficult to kill cave hydrobiids relaxed.

REPRODUCTION AND EARLY DEVELOPMEINT OF THE OCEAN QUAHOG,

ARCTICA ISLANDICA, IN THE LABORATORY

Warren S. Landers

National Marine Fisheries Service

Middle Atlantic Coastal Fisheries Center

Milford. Laboratory

Milford, Connecticut 06460

ABSTRACT

The ocean quahng. Arctica islandica, mmnaily spawns in summer in southern

New Enyland. Attempts to ripen these bivalves out of season in the labomtory

produced limited success. Clams obtained from the Rhode Island fishery in late

winter and kept in seawater ranging from 10°C to 15°C ripened significantly in

five weeks, but clams subjected to the same temperatures, plus supplemental

feeding with cultured algae in the fall, failed to produce gametes. Ripe clams

could not be induced to spawn by rapidly increasing temperature, rapidly

decreasing temperature, changing the salinity, or by sperm suspension. Fer-

tilization and the per cent developfnenl of stripped eggs to n^mnal latToe were

significantly increased when the eggs were exposed to dilute ammonium

hydroxide before fertilization was attempted. The eggs developed to the veliger

Vol. 90 (2)

THE NAUTILUS

89

larral stage best at a temperature of about 15°C. The larvae were reared to

metamorphosis at 12°C ± 2°C. Early straight-hinge stages have an unusually

long hinge line. Older larvae have low-profile tmbones that barely rise above

the hinge line; consequently, the larval outline is always round. Larvae

metamoi-phose most commonly at a length of 190-200\ji The color throughout

larval development ranges frojn colorless to a pale yellow.

During World War II a modest fishery for

A)Ttica islaudica (Linne), the ocean quahog,

sometimes called the mahogany clam, developed

off the coast of Rhode Island, but, because

other bivalve species more familiar to the con-

sumer were still plentiful, this fishery did not

expand significantly in the post-war years.

Recently, a decline in the abundance of the

more popular bivalves has spurred the govern-

ment and industry to explore the possibility of

using ocean quahog populations more efficiently

(Mendelsohn, Parker, McRae, King and Joyce,

1970). The general distribution and abundance

of these clams in the Middle Atlantic Bight

have recently been established (Merrill and

Ropes, 1969), and it is apparent that these

stocks represent a potentially valuable resource.

The purpose of this paper is to describe recent

attempts at the Milford Laboratory to develop

rearing methods for the developmental stages of

the ocean quahog as an aid to understanding

the dynamics of its natural populations and the

response of the clam to its environment.

GAMETOGENESIS

TTie reproductive cycle of Arctica in Rhode

Island waters has been described by Loosanoff

(1953). Spawning begins in late June or early

July, when the bottom water temperature over

the clam beds is about 13°C, and continues ac-

tively into early October. By late October few

animals with ripe sex products are found. After

what may be a recovery or "resting" period of

about a month, gametogenesis resumes and con-

tinues into December. While this activity slows

down with the advent of winter water tem-

peratures, both male and female clams can be

found with some morphologically mature sex

products. The gradual warming of the water in

the spring initiates a period of rapid

proliferation of sex cells until, by the end of

June, many individuals are ready to spawn.

This sequence of reproductive events suggests

that it should be easy to ripen ocean quahogs

for spawning in the laboratory during much of

the year. My attempts to accomplish this, to

date, have had only limited success, however. In

one instance, clams were obtained from the

fishery off Rhode Island in late March 1971.

The state of gonad development at this time

was as described by Loosanoff (1953); i.e. most

animals contained identifiable sex products, in-

cluding some mature eggs and active sperm, but

their numbers were small and the gonads far

from being full. These animals were kept in

flowing, unfiltered seawater at temperatures

that ranged between 10°C and 15°C. By the end

of April, the abundance of sex products had in-

creased substantially, and, when the gonad was

opened, it produced the runny appearance that

is associated with ripeness in field stocks of

this bivalve in late June. The clams remained

in this environment throughout the spring and

summer. Sex products continued to accumulate,

producing white, distended gonads. This ap-

pearance persisted until late October when a

decrease in the volume of sex products became

apparent and many of the remaining eggs ap-

peared to be breaking down.

In late November 1971, a new group was ob-

tained from the same fishery. These included a

few females with old disintegrating eggs and a

few with new, developing eggs. There were also

a few males with small numbers of motile

sperm. Most clams had empty gonads, however.

All were kept in the laboratory at 10°-15°C in

unfiltered, flowing seawater. Half of them were

additionally fed continuously with cultured

algae and the other half were not. Once a

month, thereafter, gonads fi-om each batch were

examined for sex products.

By mid-March 1972, it was apparent that

neither of the treatments had produced any

quantity of ripe gametes. Gametogenesis ap-

90 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

peared to have been stimulated to some extent

in those clams getting the supplemental algae,

but with no consistency within the group as a

whole, i.e., there were some individuals with lit-

tle or no identifiable sex products. It appeared

from these two trials that gametogenesis in the

ocean quahog can be accelerated experimentally

in the laboratory by simulating summer tem-

peratures only at certain times of the year.

AVAILABILITY AND DEVELOPMENT

OF EGGS

Loosanoff (1953) was unable to spawn ripe

ocean quahogs in the laboratory using stimuli

that work for many other bivalves. These

stimuli included a rapid increase in water tem-

perature, addition of suspensions of sex prod-

ucts, and changes in salinity. He did observe un-

provoked spawming in conditioning tanks on

two occasions, but could not relate these to any

obvious environmental condition. My own at-

tempts at various times, using the same kinds

of stimuli during the summer and early fall,

when the clams contain the most, and,

presumably, the ripest sex products, corroborate

Loosanoff 's observations. In addition,

stimulation with rapidly decreasing tem-

perature, a technique which was described by

Posgay (1953) as a dependable way to induce

spawning in sea scallops (Placopecten

magellanicus), and which we too found to work

well with this species, also failed to cause

spawning in ocean quahogs, even though these

two bivalves live in the same range of water

temperature in nature and spawn at about the

same time of the year.

Loosanoff (1953) states that the stripped ^gs

of the ocean quahog cannot be fertilized because

the germinal vesicle remains intact even after

the eggs are placed in seawater. I found that a

few stripped ^gs can be fertilized directly with

stripped sperm, but tliat more eggs can be fer-

tilized if they are treated with dilute am-

monium hydroxide before the sperm are added.

The ammonium hydroxide treatment is one that

Loosanoff and Davis (1963) used on certain

refractory species, and consists of adding 3 ml

of 0.1 NH4OH for every 100 ml of egg culture,

to a clean suspension of stripped eggs. After

the required length of exposure, the ^gs are

washed on a screen repeatedly with filtered,

UV-irradiated seawater and resuspended in the

same kind of water. The stripped sperm are

then added.

Table 1 shows the effects on Arctka eggs of

exposure to dilute NH4OH for different lengths

of time. The effects are measured in terms of

the per cent development of normal ^gs to

normal straight-hinge, veliger larvae at

12°C±2°C. The term "normal eggs" is defined

here as those eggs which after being stripped

from the gonad have, or quickly assume, the

round, solid appearance that characterizes most

naturally-spawned bivalve ^gs.

In two of the three experiments, there was

some fertilization and development of untreated

eggs, but the per cent development of treated

^gs was almost always higher and, in the best

exposure times, about three times higher than

in the controls. Exposure times between 5 and

15 minutes appear tf) give good results.

The ocean quahog is a cold water species. The

adults soon die if kept in water of 70°F (Tur-

ner, 1949). One might expect, therefore, that

their eggs would also be intolerant of high tem-

perature. Table 2, which summarizes the results

of two experiments in which the effects of dif-

ferent temperatures on the development of eggs

treated with ammonium hydroxide for 15

minutes were observed, shows this to be so.

TABLE 1. Per cent devclc/pment to the veliger stage of Arctica islandica eggs expose to NH,OH for different lengths of

time prior to feriilizatum.

Vol. 90 (2)

THE NAUTILUS

91

TABLE 2. Per cent development to the nelifier ittcii/e at different temjxratures nf Arctica islandica eggs erpused to NH,OH

for 15 minutes prior to fertilization.

Variations from the prescribed temperatures

were about ±1°C in these experiments. At tem-

peratures of 20X and above development of the

eggs to normal larvae is adversely affected.

Visual examination showed that fertilization

and early cleavage were as successful at the

high temperatures tested as at the lower ones,

but before the veliger stage was reached, most

of the embryos died. Per cent development of

eggs at 10°C and IST was approximately the

same but the rate of development was slower at

10°C. At 15°C veliger larvae were present at 48

hours after fertilization but not until about 72

hours at 10°C.

GROWTH OF THE LARVAE

Larvae were grown to metamorphosis

twice — once at lOT and once at 12°C, using

the method described by Loosanoff and Davis

(1963). A mixture of Monochrysis and Isochrysis

was used as food.

The development of the larvae from straight-

hinge to metamorphosis is, in general, un-

distinguished, with no arresting morphological

features which would serve to distinguish the

larvae from those of many other bivalves in the

plankton. With that in mind, only certain

characteristics which appear to be typical of

Arctica development are described.

The earliest, fully-shelled, straight-hinge lar-

vae average about llOfi long (parallel to the

hinge line) and 80^4 high (Fig. 1). The hinge line

is longer than that of most straight-hinge

bivalve larvae and, at this stage, averages

slightly more than SO^t In this respect the lar-

vae are similar to those of the blue mussel,

Mytilus edulis. The color is light yellow to

almost colorless. A noticeable concavity in the

hinge line is apparent in some larvae, but in

the majority it is straight. In a resting position

the larvae appear to be bilaterally symmetrical,

with little or no skewness.

FIGS. 1-3. Larval development in the ocean quahog.. Arctica

islandica. FIG. 1. Early straight -hinge larva. 110 ji fony.

FIG. 2. Late straight-hinge and early umbone larvae, 150 ii

Umg. FIG. 3. Mature larva approaching metamorphosis, 180

fi lo)ig.

92 THE NAUTILUS

April 30, 1976

Vol. 90 (2)

At a length of 150^^ the straight hinge line is

still a prominent feature in many lar\ae, but

has begun to be replaced in others by a convex

hinge line (Fig. 2). Umbones are present but

are small and of low profile and, consequently,

do not impinge on the gradually rounding

outline of the shell.

At a length of 175-180^ it is apparent that

the larvae have changed only in size and not at

all in shape, since the silhouette is still round.

In certain perspectives the umbones appear to

project very slightly above the hinge, but from

most angles they lie about even with the

slightly convex hinge line. A few larvae begin

to metamorphose at this size and can be seen

creeping along the substrate, but the most com-

mon larval length at metamorphosis is 190-200fi.

The length of larval life at both 10°C and

12°C in the laboratory was about 60 days.

Because the bottom water temperature over the

clam beds off Rhode Island does not exceed

15°C during the breeding season (Loosanoff,

1953), the slow growth of the larvae in the

laboratory at the experimental temperatures

may be accurately reflect the rate of growth of

the larvae in the field. This would force the

larvae to remain in the plankton for weeks,

possibly subjecting them to prolonged predation

and widespread dispersal, a consideration in the

proper management of the resource if it is ever

utilized lo its fullest extent.

ACKNOWLEDGMENTS

I thank Mr. George Morrison of the En-

vironmental Protection Agency Laboratory,

Narragansett. Rhode Island, for providing me

with the adult clams used in this study, and

Mr. James B. Hughes of this laboratory for

making the illustrations.

LITERATURE CITED

Loosanoff, V. L. 19.5.3. Reproductive c>'cle in Cxfprina is-

Iwidica. Biol. Bull 104(2): 146-1.5.5.

Loosanoff, V. L. and H. C. Davis. 1963. Rearing of Bivalve

Mullusks. In Russell, F. S. (ed.) Advan. Mar. Biol. 1:

M.36.

Mendelsohn, J. M.. P S. Parker, E. D. McRae, F. J. King

and A. H. Joyce. 1970. TTie ocean quahog — a bountiful

clam. F(x>d Product Development 4(7): 90, 92, 97.

Merrill, A. S. and J. W. Ropes. 1969. The general distribu-

tion of the surf clam and ocean quahog. Proc. Nat. Shell-

fi.th. Assoc. 59: 4045.

Posgay, J. A. 1953. Sea Scallop Investigations. In Sixth Re-

port on Investigations of the Shellfisheries of Massachu-

setts. Mass. Dept. Conservation, Div. Marine Fisheries,

pp. 9-24.

Turner, H. ,J. 1949. The Mahogany Quanaug Resources of

Mas.sachusetts. /« Report on Investigations of Methods of

Improving the Shellfish Resources of Massachusetts. Mass.

Dept. Conservation, Div. Marine Fisheries, December 31,

1949, pp. 12-16.

PUBLICATIONS RECEIVED

Ros, Joandomenec. 1975. Opistobranquios (Gastro-

poda: Euthyneura) del litoral iberico. Investi-

gacion Pesquera, vol. 39, no. 2, pp. 269-372, 4

pis. (3 in color). Barcelona, Spain. Ecology, foixi

preferences, and brief synonymies of 102 spe-

cies of littoral opisthobranchs from Spain and

Tangiers.

Taylor, John and Jerry G. Walls, 1975, Courriea.

288 pp., numerous color photos, wall chart in-

cluded. T. F. H. Publications, New Jersey

$14.95. Despite a number of spelling mistakes

and a few misidentifications, this is the best

buv in Cowrie books for amateurs.

Humfrey, Michael. 1975. Sea Shells of the West

Indies. 351 pp., 20 text figs., 32 colored plates.

Taplinger Publishing Co., N. Y. $19.95. This

book is very similar to Caribbean Seashells by

Wamike and Abbott, but has more colored

plates, and 48 species not in the latter. How-

ever, 272 species found in Caribbean Seashells

are not included. The drawings are copies from

Caribbean Seashelh and American Sea.thelL%

first edition. The nomenclature does not in-

clude changes and updatings found in the se-

cond, 1974, edition of American Seashelh.

Abbott, R. Tucker. 1976. Seashells. 160 pp., 184

color pis. Bantam Books, Inc., N. Y. Paperback,

$1.9.5. Introduction to the shells of the

seven seas.

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MOLLUSK VOUCHER SPECIMENS

It is becoming increasingly important for

future research purposes that an identified sam-

pling of species mentioned in publications be

deposited in a permanent, accessible museum

specializing in mollusks. This is particularly

true of mollusks used in physiological, medical,

parasitological, ecological, and experimental

projects.

The Delaware Museum of Natural History

has extensive modern facilities and equipment

for the housing and curating of voucher

specimens. Material should be accompanied by

the identification, locality data and its

bibliographic reference. There is no charge for

this permanent curating service, and catalog

numbers, if desired, will be sent to authors

prior to publication.

JULY 1976

THE

NAUTILUS

Vol. 90

No. 3

A quarterly

devoted to

malacology and

the interests of

conchologists

Founded 1889 by Henry A. Pilsbry. Continued by H. Burrington Baker.

Editor-in-Chief: R. Tucker Abbott

EDITORIAL COMMITTEE

CONSULTING EDITORS

Dr. Arthur H. Clarke, Jr.

Department of MoUusks

National Museum of Canada

Ottawa, Ontario, Canada K1A-0M8

Dr. WUliam J. Clench

Curator Emeritus

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. William K. Emerson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 10024

Mr. Morris K. Jacobson

Department of Living Invertebrates

The American Museum of Natural History

New York, New York 10024

Dr. Aurele La Rocque

Department of Geology

The Ohio State University

Columbus, Ohio 43210

Dr. James H. McLean

Los Angeles County Museum of Natural History

900 Exposition Boulevard

Los Angeles, California 90007

Dr. Arthur S. Merrill

Biological Laboratory

National Marine Fisheries Service

Oxford, Maryland 21654

Dr. Donald R. Moore

Division of Marine Geology

School of Marine and Atmospheric Science

10 Rickenbacker Causeway

Miami, Florida 33149

Dr. Joseph Rosewater

Division of MoUusks

U. S. National Museum

Washington, D.C. 20560

Dr. G. Alan Solem

Department of Invertebrates

Field Museum of Natural History

Chicago, Illinois 60605

Dr. David H. Stansbery

Museum of Zoology

The Ohio State University

Columbus, Ohio 43210

Dr. Ruth D. Turner

Department of MoUusks

Museum of Comparative Zoology

Cambridge, Mass. 02138

Dr. Gilbert L. Voss

Division of Biology

School of Marine and Atmospheric Science

1 0 Rickenbacker Causeway

Miami, Florida 33149

Dr. Charles B. Wurtz

3220 Penn Street

Philadelphia, Pennsylvania 19129

EDITOR-IN-CHIEF

Dr. R. Tucker Abbott

Delaware Museum of Natural History

Box 3937, Greenville, Delaware 19807

Mrs. Horace B. Baker

Business and Subscription Manager

1 1 Chelten Road

Havertown, Pennsylvania 1 9083

OFFICE OF PUBLICATION

Delaware Museum of Natural History

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Box 3937, GreenviUe, Delaware 19807

Second Class Postage paid at Wilmington, Delaware

Sut>scrlptlon Price: $7.00 (see Inside back cover)

THE

NAUTILUS

Volume 90, number 3 — July 21, 1976

CONTENTS

Review (of W. K. Emerson and M. K. Jacobson) vi

Wayne Leathern, Peter Kinner and Don Maurer

Northern Range Extension of the Florida Marsh Clam CyrenoidaJloTidana

(Superfamily Cyrenoidacea) 93

David Bickel

Two New species of Non-marine Mollusca from the Fort Union Group

(Paleocene) of North Dakota and Montana 94

Artie L. Metcalf and David H. Riskind

A New Humboldtiana (Pulmonata: Helminthoglyptidae) from Coahuila, Mexico 99

Raymond W. Neck and Richard W. Fullington

Anomalous Land Gastropods from Texas (Polygyridae and Urocoptidae) 101

Leslie Hubricht

Notes on Some Land Snails of the Eastern United States 104

Alan Solem

Status oiSuccinea ovalis chittenangoensis Pilsbry, 1908 107

Fred E. Wells

Growth Rate of Four Species of Euthecosomatous Pteropods

Occurring off Barbados, West Indies 114

J. A. Gardner, Jr., W. R. Woodall, Jr.,

A. A. Staats, Jr. and J. F. Napoli

The Invasion of the Asiatic Clam {Corbicula manilensis Philippi)

in the Altamaha River, Georgia 117

N. V. Subba Rao and S. C. Mitra

Succiyiea nun New Name for Siwcinea arboricola Rao, 1925

(Stylommatophora: Succineidae) 125

BOOK REVIEW

Emerson, William K. and Morris K. Jacobson.

1976. Guide to ShelU: Land, Frej^hunter, and

Marine, fi-om Nova Scotia to Florida, .wiii + 482

pp., 47 pis. (16 in color). Alfred A. Knopf, N. Y.

Hardcover, $17.50; paperback, $8.95.

This husky little guide with its attractive il-

lustrations and entertaining, as well as accurate,

text should be a pcjpular sheller's reference book

to the common shells of the seashore, streams and

woods of eastern United States. Numeroas keys

to all of the species covered in the book, and a

wealth of etymological data for the lovers of the

origin of names, are outstanding features.

The selection of the 524 species of marine

shells, except for a few dozen species requiring a

microscope for identification, will help the

amateur, although other similar books treat with

many more. Most useful under this one cover are

several hundred, rather well-illustrated, land and

freshwater mollusks.

Somewhat of a drawback created by the book

designer is the use of difficult-to-remember ro-

man numerals for the plates (XLII, XXXK,

etc.), and the main species not being put in

boldface type. The origin of the scientific names

is very well done, but, parenthetically, Helicina

clappi was named after the venerable land-shell

taxonomist, George Hubbard Clapp, and not for

the Cape Cod shipworm specialist, William F.

Clapp. Amateurs and some professionals will be

dismayed over the re-arrangement of the scien-

tific names of the Biisycon whelks. The il-

lustrated holotype of Linnaeus' pervermm (The

Nautilus, vol. 53, pi. 7) is almost identical to what

they label as kieneri. Nonetheless, this is a very

praiseworthy shell book.

R. Tucker Abbott

Delaware Museum of Natural HiMory

THE NAUTILUS

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A Bicentennial Anthology

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Edited by R. Tucker Abbott

american malacologists

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VI

Vol. 90 (3)

July 21, 1976

THE NAUTILUS 93

NORTHERN RANGE EXTENSION OF THE FLORIDA MARSH CLAM

CYRENOIDA FLORIDANA (SUPERFAMILY CYRENOIDACEA)

Wayne Leathern, Peter Kinner and Don Maurer

College of Marine Studies

University of Delaware

Lewes, DE 19958

The small bivalve, Cyrenoida floridana (Dall,

1896), was collected in the Canary Creek Marsh,

Delaware, at 38°48'45" north latitude and 75° 10'

west longitude. In May 1975, 15 samples were col-

lected in connection with a marsh productivity

study. On the average, 12 specimens were found

in every 1/4 m^ sample. The clams attaining a

length of 9 mm occurred most abundantly among

FIGS. 1-3. Cyrenoida floridana (DalL 1896) from Canary

Creek, Delaware. 1, hinge of left valve. X200. 2, hinge of

right valve. X200. 3, dorsal view of bivalve. XlOO.

the layer of detritus at the base of the marsh

grasses.

The range for C. floridana had previously been

reported from Georgia to southern Florida (Dall,

1896). This constitutes a northern range extension

of approximately 900 km and crosses a major

zoogeographic boundary (Abbott, 1968; Cerame-

Vivas and Gray, 1966). The description of these

specimens agrees with Abbott (1974, p. 466, fig.

5385).

To ascertain more information about the den-

sities and ecology of C. floridana, 15 stations

tent and volatiles, sand, silt and clay. Eh, and

altemiflora (tall and dwarf), S. patens, and

Dii^tichlis .'ipicata zones. The percent of water con-

tent and volatiles, sand, silt and clay. Eh, and

surface salinity were sampled at each location.

A 0.1 m^ sample of sediment taken from the base

of each of the grasses was sieved over a 1 mm

screen and the number of C. floridana was

recorded.

The area with the highest density of C.

floridana was the D. spicata (15.0/0.1 m^) zone.

The dwarf S. altemiflora (3.0/0.1 m^) area was

the only other area where appreciable numbers of

individuals were found. A few specimens were

recorded in the -S. patens and S. altemiflora

zones.

Of the environmental data collected only the

percentage of volatiles and water content showed

any association with the observed densities of C.

floridana. The D. spicata and dwarf S. alter-

niflora had mean water contents of 238.4 (± 81.5)

and 273.8 (± 104.1), respectively, while the tall S.

altemiflora value was only 80.7 ± 26.7. The per-

centage of volatiles was also higher in the D.

spicata (-210.0 ± 7.4) and dwarf S. altemiflora (21.8

± 8.5) areas than in the creekside tall Spartina

(6.76 ± 2.02).

94 THE NAUTILUS

July 21, 1976

Vol. 90 (3)

From this limited evidence it may be specu-

lated that the high water content of the sedi-

ments containing C. floridana may be impor-

tant in facilitating the life functions between

daily inundations in the marsh areas where it

lives. The high volatile content of the sediments

inhabited by C. floridana should be examined

more closely for its possible nutritive role.

The stem densities in the D. apicata and dwarf

S altemijhra zones are far greater than those in

the tall S. atternijlora. This may be very impor-

tant in stabilizing the sediment and lessening the

effect of light and temperature on marsh surface

containing the clam (Kraeuter and Wolf, 1974).

At the suggestion of Dr. R. Tucker Abbott, who

kindly verified the identification (Del. Mus. Nat.

Hist., No. 102,538), we offer a figure to supple-

ment the illustration in Abbott (1974). We would

like to thank our colleague, Mr. Phil Averill, who

collected and brought these specimens to our at-

tention.

LITERATURE CITED

Abbott. R. T.. 1968. Seashells of North America. A Golden

Field Guide. Golden Press, N. Y., pp. 268.

Abbott. R. T., 1974. American Seashells. Second Edition. Van

Nostrand Reinhold Co., N. Y., pp. 66a

Cerame-Vivas, M. J., and I. E. Gray. 1966. The distribution

pattern of benthic invertebrates of the continental shelf

off North Carolina. Ecology 47(2): 51-52.

Dall, William Healey, 1896 On the American species of

Cyrenoidea. The Nautilus 10(5): 51-52.

Kraeuter. J. N. and P. L. Wolf. 1974. The relationship of

marine macroin vertebrates to salt marsh plants. In:

R. J. Reimold and W. H. Queen, eds. Ecology of Halophytes.

Academic Press, N. Y., pp. 449-462.

TWO NEW SPECIES OF NON-MARINE MOLLUSCA FROM THE FORT

UNION GROUP (PALEOCENE) OF NORTH DAKOTA AND MONTANA

David Bickel

Minot State College

Minot, North Dakota 58701

ABSTRACT

Two new species of fossil freshwater moUusks are described from the Paleo-

cene Tongue River and Sentinel Butte Formations of North Dakota and Mon-

tana. Eupera missouriensis n. sp. is a pisidiid clam related to K formosa (Meek

and Hayden). Bellamya campjaniformis n. sp., a vimparid snail, occurs in the

lowei' and middle Tongue River Formation and possibly in the Paskapoo Fcrr-

mation of Alberta.

INTRODUCTION

Pioneering work on Fort Union mollusks and

stratigraphy was done by F. B. Meek and F. V.

Hayden between 18.56 and 1860. Meek (1876) sum-

marized the p)aieont<)l()gy of the region and listed

about 25 non-marine species of mollusks then

known to occur in the Paleocene of the Williston

Basin. With the exception of studies in the

Saskatchewan portion of the basin summarized

by Russell (1974) and other, scattered reports,

most data on Paleocene mollusks of the Northern

Great Plains has come from work in other

sedimentary basins.