European Journal of Taxonomy 135: 1-19

http://dx.doi.org/10.5852/ejt.2015.135

This work is licensed under a Creative Commons Attribution 3.0 License.

ISSN 2118-9773

www. europeanj ournaloftaxonomv. eu

2015 • Galea H R.

Research article

urn:lsid:zoobank.org:pub:F5F578C8-4CA7-4ADA-9DAF-0DA5170E9F9F

Two new genera and nine new species of hydroids

(Cnidaria: Hydrozoa) from off New Caledonia

Horia R. GALEA

Hydrozoan Research Faboratory, 405 Chemin des Gatiers, 83170 Tourves, France.

E-mail: horia.galea.@gma 11 com

urn:lsid:zoobank.org:author:DE5AC672-0243-46F2-A910-AFF4E91A4C5D

Abstract. Two new genera and nine new species of hydroids are described based on deep-water material

collected from off New Caledonia during various expeditions of the French Tropical Deep-Sea Benthos

program. Caledoniana gen. nov., provisionally included in the family Sertulariidae Famouroux, 1812,

presently comprises three new species, viz. C. alata sp. nov., C. decussata sp. nov., and C. microgona

sp. nov., while an additional group of three new species, is accommodated in the new sertulariid

genus Solenoscyphus gen. nov.: S. candelabrum sp. nov., S. decidualis sp. nov., and S. striatus sp. nov.

Furthermore, three new species of Hincksella Billard, 1918 (family Syntheciidae Marktanner-

Turneretscher, 1890) are described, namely H. cornuta sp. nov., H. neocaledonica sp. nov., and

H. similis sp. nov.

Key words. New species, western Pacific, deep-water.

Galea H.R. 2015. Two new genera and nine new species of hydroids (Cnidaria: Hydrozoa) from off New Caledonia.

European Journal of Taxonomy 135: 1-19. http://dx.doi.org/10.5852/eit.2015.135

Introduction

Targe collections of hydroids were gathered during numerous French expeditions, conducted conjointly

by the Institut de Recherche pour le Developpement (IRD, formerly ORSTOM) and the Museum

national d’Histoire naturelle (MNHN) of Paris, in the tropical southwestern Pacific. Faunched early

in the 1980’s as the MUSORSTOM campaigns and continuing until today under the name Tropical

Deep-Sea Benthos, these expeditions aimed at exploring the deep-sea fauna (down to 1500 m) of a

vast geographical area extending from Taiwan to the Marquesas, and encompassing the Philippines,

the Banda Sea, the Solomon Islands, New Caledonia, Vanuatu, Wallis and Futuna, Fiji, Tonga, and the

Austral Islands (Bouchet et al. 2008).

Accounts of some genera and/or families of hydroids secured by these expeditions have already been

published over the last two decades: Sertulariidae and, to a much lesser extent, Thyroscyphidae (Vervoort

1993), Halopterididae (Ansin Agis et al. 2009), Acryptolaria (Pena Cantero & Vervoort 2010), and

Kirchenpaueriidae (Ansin Agis et al. 2014).

A collection of specimens not studied by Vervoort (1993) or collected after the publication of

his monograph, comprising species belonging to various genera of Sertulariidae, Syntheciidae,

European Journal of Taxonomy 135: 1-19 (2015)

Thyroscyphidae, Campanulariidae, and Haleciidae, was entrusted to me for study. The present report is

the first account, based on a fraction of the material in this collection, and deals particularly with nine

new species of hydroids, of which six are accommodated in two new genera of sertulariids, while the

remaining three belong to the syntheciid genus Hincksella Billard, 1918.

Material and methods

The methods of study were described in detail by Galea (2007, 2008). Station numbers, as indicated in

the text, are preceded by a two-letter prefix referring to the sampling gear used to secure the material,

either a Waren dredge (DW) or a beam trawl (CP). The material is deposited in the collections of MNHN.

Results

Phylum Cnidaria Verrill, 1865

Class Hydrozoa Owen, 1843

Subclass Hydroidolina Collins & Marques, 2004

Order Teptothecata Cornelius, 1992

Family Sertulariidae Tamouroux, 1812

Genus Caledoniana gen. nov.

urn:lsid:zoobank.org:act:7D2C6D92-C02C-4977-A568-4A5F277389A4

Diagnosis

Erect, loosely-branched, fan-shaped, weakly-fascicled colonies; branching pattern sparing and irregular;

division into internodes indistinct; hydrothecae given off in opposite, though not contiguous pairs, except

for the first hydrothecae of the side branches which are unpaired; successive pairs of hydrothecae either

coplanar or, occasionally, adopting a decussate arrangement; hydrothecae very large, tubular, free for

at least half their length, closed by rounded, deciduous opercula; gonothecae club-shaped to piriform,

inserted slightly laterally, below the hydrothecal bases.

Etymology

Named after the area of occurrence of its species. New Caledonia. The genus name is a feminine noun.

Type species

Caledoniana a lata sp. nov.

Remarks

The new genus is provisionally placed within the family Sertulariidae owing to the presence of

hydrothecal opercula, though molecular analyses, based on freshly-collected samples, are needed to

confirm this.

Together with Gigantotheca Vervoort & Watson, 2003, Caledoniana gen. nov. is distinguished from other

genera through the presence of huge, tubular hydrothecae, both genera forming a clearly distinct group

within the family. Unlike Gigantotheca , in which the hydrothecae are alternate, those of Caledoniana

gen. nov. are grouped in opposite pairs, analogous to the generic separation of Hincksella Billard, 1918

and Synthecium Allman, 1872, respectively, in the family Syntheciidae.

The hydrothecae of Caledoniana gen. nov. superficially resemble those of Staurotheca Allman, 1888,

especially through the presence of deciduous opercula with no definite points of attachment (see Pena

Cantero et al. 1997: 336). However, the hydrothecae of the latter are arranged in two or multiple

GALEA H.R., New hydroids from New Caledonia

longitudinal rows, they are generally deeply immersed in both stems and branches, and their size is

much smaller in all species described so far (Pena Cantero et al. 1997, 1999; Pena Cantero & Vervoort

2003a, 2003b).

Staurotheca megalotheca Vervoort & Watson, 2003, a species of so far uncertain generic position,

possesses huge hydrothecae arranged in either opposite pairs or decussate groups of three (Vervoort &

Watson 2003), suggesting obvious affinities with Caledoniana gen. nov., in particular with C. decussata

sp. nov. (see below).

Key to species

1. Free part of hydrothecae curved upward. C. alata sp. nov.

- Free part of hydrothecae straight .2

2. Some pairs of hydrothecae adopting a decussate arrangement. C. decussata sp. nov.

- Successive pairs of hydrothecae always coplanar. C. microgona sp. nov.

Caledoniana alata sp. nov.

urn:lsid:zoobank.org:act:9B3A55AF-D726-41DA-AA96-B3D8B9836BC5

Figs 1A, 2A-B; Table 1

Diagnosis

Colonies lightly fascicled basally, loosely branched, coplanar; nodes indistinct, internodes short;

hydrothecae in opposite pairs and coplanar series; long, tubular, free part distinctly curved upward;

gonothecae large, piriform.

Fig. 1. A Caledoniana alata gen. et sp. nov., holotype (below) and paratype (above). B. Caledoniana

decussata gen. et sp. nov., colony silhouette (part of holotype). C. Caledoniana microgona gen. et sp.

nov., colony silhouette (holotype). The red arrows indicate the presence of gonothecae. Scale bars: 1 cm.

European Journal of Taxonomy 135: 1-19 (2015)

Etymology

From the Latin alatus , meaning "winged", making reference to the shape of the hydrothecae, recalling

the wings of a gliding bird.

Type material

Holotype

NEW CALEDONIA: campaign Bathus 4, station DW923, 18°52’ S, 163°24’ E, 502^170 m, 6 Aug.

1994; 3.6 cm high, branched fragment bearing a mature gonotheca (IK-2012-10287).

Paratype

NEW CALEDONIA: data as for holotype; 4.6 cm high, branched fragment bearing a mature and an

immature gonotheca (IK-2012-10288).

Description

Two stem fragments, 3.6 and 4.6 cm high, with no hydrorhizae, possibly detached at base from same

colony; lightly fascicled proximally, with a few accessory tubes creeping over main tube bearing

hydrothecae. No evident division into internodes, even in monosiphonic parts. Each equivalent of

internode short, accommodating pair of opposite, though not contiguous, hydrothecae. Single side

branches, given off laterally from below a stem hydrotheca, occur in both specimens; structure similar

to that of stem, except for first hydrotheca, which is unpaired. Hydrothecae large, tubular, immersed

for about half their length into their corresponding internodes; free parts bent at nearly right angles

to intemodes, then curving upwards toward their middle; diameter nearly constant for most of length,

slightly expanding toward aperture; rim with thickened perisarc; in frontal view, aperture semi-circular

on adaxial side and somewhat flattened on abaxial side; a filmy, rounded operculum observed in one

hydrotheca, but opercula likely deciduous. Gonothecae large and pyriform, with no distinct aperture; at

least three large, globular structures (oocytes or young embryos) present in one of them. Numerous, large

foramina (obliterated by thin pellicle of perisarc) below each hydrotheca suggest that gonothecae may

occur in pairs in fully fertile specimens. Coenosarc badly preserved, not suitable for tentacle counting

or cnidome studies.

Remarks

The hydrothecae are so large that sand grains partially or totally fill their lumina. In this case, the finding

of an operculum closing the aperture of a hydrotheca is truly fortunate.

Caledoniana decussata sp. nov.

urn:lsid:zoobank.org:act:B302DBCl-9E6F-427F-A3B6-3843F8FAE77C

Figs IB, 2C-D; Table 1

Diagnosis

Colonies lightly fascicled basally, loosely branched, coplanar; nodes indistinct, internodes relatively

short; hydrothecae in opposite pairs in both coplanar and decussate series; long, tubular, free part straight.

Etymology

From the Latin decusso, meaning "to form or create a cross in the form of an X", to characterize the

arrangement of the hydrothecal pairs in this species.

GALEA H.R., New hydroids from New Caledonia

Material examined

Holotype

NEW CALEDONIA: campaign Bathus 2, station CP737, 23 o 03 , S, 167°00’ E, 357-400 m, 13 May

1993; 5.5 cm high, sterile colony attached to mineral concretion and adjacent sponge, as well as 3

smaller fragments detached from it (IK-2012-10289).

Fig. 2. — A-B Caledoniana alata gen. et sp. nov. A. Portion of fertile stem (note gonotheca above) and

basal part of a side branch, showing positions of hydrothecae. B. Hydrotheca. — C-D. Caledoniana

decussata gen. et sp. nov. C. Portion of stem with first and second order side branches from region of

colony with coplanar hydrothecae, showing their relative position. D. Hydrotheca. — E-G. Caledoniana

microgona gen. et sp. nov. E. Portion of stem. F. Hydrotheca. G. Three gonothecae. Scale bars: A, C, E,

G = 3 mm; B, D, F = 1 mm.

European Journal of Taxonomy 135: 1-19 (2015)

Description

Colony erect, 5.5 cm high, arising from rhizoid stolon firmly attached to substrate. Basal part of stem

fascicled, with several accessory tubes creeping over main tube; in monosiphonic parts, division into

internodes indistinct; each equivalent of intemode relatively short, bearing a pair of opposite, though not

contiguous, hydrothecae. Branching sparse and irregular, up to 2 nd order; side branches given off singly or

in pairs from below a stem hydrotheca; stem and side branches coplanar; structure of latter similar to that

of stem, except for first hydrotheca, which is usually unpaired, though a pair of hydrothecae also occurs

within colony. Basal parts of stem and side branches with successive pairs of hydrothecae in coplanar

series; more distally, pairs become decussate. Hydrothecae large, tubular, adnate for about half of length,

or less, to corresponding internodes; free part bent at about 45°; diameter nearly constant throughout,

slightly expanding at rim; rim conspicuously thickened; aperture circular in frontal view; opercula not

seen. Gonothecae absent, though basal remains at insertion of one of these (below a hydrotheca) present;

numerous, large foramina (obliterated by thin pellicle of perisarc) below most hydrothecae, making the

possibly future insertion points for them. Coenosarc badly preserved, not suitable for tentacle counting

or cnidome studies.

Caledoniana microgona sp. nov.

um:lsid:zoobank.org:act:798CB04B-5AB6-48B2-962D-AD9F6FE56D65

Figs 1C, 2E-G; Table 1

Diagnosis

Colonies lightly fascicled basally, loosely branched, coplanar; nodes indistinct, internodes relatively

long; hydrothecae in opposite pairs and coplanar series; long, tubular, free part slightly convex basally,

then straight; gonothecae small, club-shaped.

Etymology

From the Greek pucpoQ, meaning "small", and ydvog, meaning "seed", to characterize the size of its

gonothecae.

Material examined

Holotype

NEW CALEDONIA: campaign Biocal, station DW46, 22°53’ S, 167°17’ E, 570-610 m, 30 Aug. 1985;

7.3 cm high colony with one gonotheca (IK-2012-10290).

Paratypes

NEW CALEDONIA: data as for holotype; numerous fragmented stems up to 6.3 cm high, some sterile,

as well as several detached gonothecae (IK-2012-10291).

Description

Colonies erect, up to 7 cm high, fan-shaped, loosely fascicled on basal portions of stems and some

lower side branches. Main tube indistinctly divided into moderately long internodes, each of them

bearing a distal pair of opposite, though not contiguous, hydrothecae. Side branches sparse, given off

irregularly and laterally from below a hydrotheca; up to 2 nd order branching. First hydrotheca of side

branch commonly unpaired, although one colony with paired hydrothecae. Hydrothecae large and

tubular, immersed for about one-third of adaxial length into internode; free part of nearly constant

diameter, projecting outward at wide angle; abaxial wall slightly tumid at inflexion point, then straight

distally; free adaxial side slightly convex basally, then parallel to abaxial counterpart; rim thickened;

aperture borne on slight terminal constriction of hydrothecal wall; in frontal view rounded on adaxial

side and flattened abaxially; opercula not seen. Gonothecae given off slightly laterally from below bases

GALEA H.R., New hydroids from New Caledonia

Table 1. Measurements of species of Caledoniana gen.

nov., in pm.

C. alata sp. nov.

C. decussata sp. nov.

C. microgona sp. nov.

Stem

“Internode” length

3500M000

2500-3000

3000-3700

Diameter at “node”

675-735

530-665

445-665

Hydrotheca

Adaxial side free

2265-2530

1730-1875

2100-2475

Adaxial side adnate

1980-2420

1620-1830

1170-1420

Abaxial side

3845M130

2860-3075

2630-2955

Width

615-725

465-510

530-590

Diameter at rim

650-870

515-550

495-605

Gonotheca

Length

6250 (gonotheca #1)

6750 (gonotheca #2)

—

2750-3250

Maximum width

3300 (gonotheca # 1)

2600 (gonotheca #2)

1040-1160

of hydrothecae; small and club-shaped, with thick perisarc. Coenosarc badly preserved, not suitable for

tentacle counting or cnidome studies.

Remarks

Like in C. decussata gen. et sp. nov., the free parts of the hydrothecae of this species are almost straight,

thus differing from the sigmoid shape met with in C. alata gen. et sp. nov. However, in C. decussata gen.

et sp. nov. the hydrothecal pairs may exhibit a decussate arrangement; their free part is comparatively

shorter, while the adnate one is longer.

Genus Solenoscyphus gen. nov.

um:lsid:zoobank.org:act:B69365F9-2052-4A94-8AF4-2456E46DA678

Diagnosis

Colonies of various sizes and shapes, from irregularly branched to pinnate, with either mono- or

polysiphonic stems; cladia always monosiphonic. Hydrothecae long, tubular, with either straight or

curved axes, adnate for less than half their length to the internodes; bases as complete septa; opercula

filmy and rounded in shape, with indistinct points of attachment, clearly deciduous. Perisarc either

smooth or finely and densely striated. Gonothecae unknown.

Type species

Solenoscyphus candelabrum sp. nov.

Etymology

From the Greek (jcolr/vosiSr/g, meaning "tubular", and cncbipog, meaning "cup", to characterize the shape

of the hydrothecae. It is a masculine noun.

Remarks

Unlike other sertulariid genera whose hydrothecae are provided with either an adaxial (Abietinaria

Kirchenpauer, 1884, Diphasia Agassiz, 1862, Idiellana Cotton & Godfrey, 1942, and Papilionella

European Journal of Taxonomy 135: 1-19 (2015)

Antsulevich & Vervoort, 1993) or an abaxial (Salacia Lamouroux, 1816 and Thuiaria Fleming, 1828)

opercular flap (Bouillon et al. 2006), the new genus possesses a deciduous operculum with no definite

point of attachment.

In this respect, it shows similarities with both Caledoniana gen. nov. and Staurotheca Allman, 1888, and

this may prove to be equally true for Gigantotheca Vervoort & Watson, 2003 as well. As shown above,

Caledoniana gen. nov. is characterized by the presence of huge hydrothecae, a situation not met with in

any of the three species described below. On the other hand, Staurotheca comprises a majority of species

exhibiting a characteristic arrangement of the hydrothecae in decussate groups, although in a few cases

they are either subopposite (S. amphorophora Naumov & Stepanjants, 1962, S. australis Pena Cantero

et al. , 1997, and S. vervoorti El Beshbeeshy, 2011) or decidedly alternate (S. abyssalis Pena Cantero &

Vervoort, 2003 and S. profunda Pena Cantero & Vervoort, 2003). In addition, the hydrothecae of most

species of Staurotheca are deeply immersed in both the stem and side branches; they characteristically

curve outwards and their bases are often incomplete septa. Moreover, the colony shape in that genus

is radically different, ranging from bush-like (with no distinct stems) to fan-shaped or tree-like (Pena

Cantero & Vervoort 2003a). Unlike the tropical Solenoscyphus gen. nov., Allman’s (1888) genus is

essentially Antarctic, with a few species also occurring in the sub-Antarctic and some localities in South

America (Pena Cantero & Vervoort 2003a).

Key to species

1. Free part of hydrothecae curved upward. S. candelabrum sp. nov.

- Free part of hydrothecae straight .2

2. Perisarc striated throughout, apex of hydrotheca swollen. S. striatus sp. nov.

- Perisarc smooth, hydrotheca isodiametric throughout. S. decidualis sp. nov.

Solenoscyphus candelabrum sp. nov.

urn:lsid:zoobank.org:act:88847458-73D4-42Bl-B553-4AD070BC2AFA

Figs 3A, 4A-B; Table 2

Diagnosis

Colonies regularly pinnate, stems polysiphonic, cladia always monosiphonic; nodes indistinct; stem

internodes composed of an apophysis, an axillary hydrotheca, two alternate hydrothecae above,

another apophysis opposite to the former, and an axillary hydrotheca; cladial internodes, each with one

hydrotheca; hydrothecae alternate throughout, long, tubular, free part distinctly concave, facing upward;

operculum deciduous.

Etymology

From the Latin candelabrum , meaning "candlestick", with reference to the shape of the hydrothecae,

the whole colony resembling a phantasmagoric candelabrum with an infinity of arms. Used as a noun

in apposition.

Material examined

Holotype

NEW CALEDONIA: campaign Bathus 4, station DW923, 18°52’ S, 163°24’ E, 502^170 m, 6 Aug.

1994; 9.0 cm high, sterile colony (IK-2012-10292).

Paratypes

NEW CALEDONIA: data as for holotype; four sterile colonies 5.7-12.0 cm high (IK-2012-10293).

GALEA H.R., New hydroids from New Caledonia

Description

Stems up to 12 cm high, arising from disc-shaped hydrorhizae firmly attached to substrate; strongly

polysiphonic basally, uniformly grading to monosiphonic towards apices; auxiliary tubes running up,

nearly parallel to main tube and establishing occasional anastomoses with each other. Nodes generally

poorly indicated, though division into internodes with apparently unusual repetitive sequence: proximal

node, short lateral apophysis (supporting a cladium), axillary hydrotheca, two alternate hydrothecae

above, second cladial apophysis on opposite side to former, axillar hydrotheca, and distal node. Cladia

pinnately arranged, given off at about 70° to stem, up to 3 cm long; straight, unbranched, exclusively

monosiphonic; inserting on corresponding stem apophyses by means of short, rectangular, ahydrothecate

intemodes; nodes indistinct. Hydrothecae of both stem and cladia biseriate, alternate, and coplanar;

tubular, S-shaped, facing out- and upward; a prominent internal perisarc thickening occurring along

median line of lower half of abaxial wall, together with a transverse ridge arising from middle part of

perisarcal thickening, and extending over both “frontal” and “dorsal” sides of theca; elsewhere perisarc

relatively thin; in frontal view, aperture of hydrotheca rounded adaxially and slightly flattened abaxially;

deciduous opercula rarely seen at apertures of some hydrothecae. Gonotheca unknown.

Solenoscyphus decidualis sp. nov.

um:lsid:zoobank.org:act:E4FDE6E2-065E-43CC-B978-126563826AA9

Figs 3B, 4C-D; Table 2

Diagnosis

Colonies regularly pinnate, stems polysiphonic, cladia always monosiphonic; nodes indistinct; stem

internodes composed of two alternate hydrothecae, an apophysis, and an axillary hydrotheca; cladial

internodes each with one hydrotheca; the latter alternate, long, tubular, free part slightly convex basally,

then straight; operculum deciduous.

Etymology

From the Latin deciduus , meaning "deciduous", with reference to the condition of the hydrothecal

operculum.

Material examined

Holotype

NEW CALEDONIA: campaign Biocal, station DW38, 23°00’ S, 167°15’ E, 360 m, 30 Aug. 1985;

4.0 cm high, sterile colony (IK-2012-10294).

Description

Essential part of hydrorhiza missing, but remains of what appears to be a rhizoid stolon, firmly attached

to substrate, could be seen. Colony erect and pinnate, ca. 4 cm high. Stem lightly fascicled basally,

grading to monosiphonic distally; auxiliary tubes fused to one another, forming outer layer of perisarc

enveloping main tube; monosiphonic part of stem with indistinct nodes; equivalents of internodes

composed of proximal “node”, two alternate hydrothecae, short lateral apophysis (supporting cladium)

on side opposite to second hydrotheca, axillary hydrotheca, and distal “node”. Cladia up to 1.2 cm long,

inserted on corresponding stem apophyses, occurring at an angle of about 70° with stem; nodes indistinct;

equivalents of internodes relatively short, each carrying a hydrotheca on its distal half. Hydrothecae of

both stem and cladia biseriate, alternate, given off at 70-75° to “internodes”; tubular, adnate for one-

fourth of adaxial length; both free adaxial and abaxial walls parallel, imperceptibly convex to almost

straight; rim even, aperture circular, placed at right angle to axis of theca; rare, rounded opercula close

apertures of some hydrothecae. Gonotheca unknown.

European Journal of Taxonomy 135: 1-19 (2015)

Solenoscyphus striatus sp. nov.

urn:lsid:zoobank.org:act:6ED544D2-AD80-469D-AF97-DFE1062D6E0D

Figs 3C, 4E-G; Table 2

Diagnosis

Colonies lightly fascicled basally; branching irregular, in one plane; nodes indistinct; each internode

relatively short, bearing a hydrotheca; the latter long, tubular, facing outward and upward, apically

swollen; operculum deciduous; perisarc of colonies densely and finely striated.

Etymology

From the Fatin striatus , meaning "marked with striae", to characterize the external condition of the

perisarc.

Material examined

Holotype

NEW CAFEDONIA: campaign Bathus 2, station CP737, 23°03’ S, 167 o 00’ E, 357^400 m, 13 May

1993; sterile colony fragment 5.2 cm high (IK-2012-10295).

Paratype

NEW CALEDONIA: data as for holotype; sterile colony fragment 3.1 cm high (IK-2012-10296).

Fig. 3. A. Solenoscyphus candelabrum gen. et sp. nov., colony silhouette (holotype). B. Solenoscyphus

decidualis gen. et sp. nov., colony silhouette (holotype). C. Solenoscyphus striatus gen. et sp. nov.,

colony silhouette (holotype). Scale bars: A = 2 cm; B-C = 1 cm.

GALEA H.R., New hydroids from New Caledonia

Description

Smaller specimen (paratype) 3.1 cm high, comprising a branched fragment of either a stem or a side

branch; larger specimen (Fig. 3C, holotype) 5.2 cm high, possibly a branched stem missing hydrorhiza;

Fig. 4. — A-B. Solenoscyphus candelabrum gen. et sp. nov. A. Portion of stem with basal parts of five

cladia. B. Hydrotheca, showing internal projections of the perisarc. — C-D. Solenoscyphus decidualis

gen. et sp. nov. C. Portion of stem with basal parts of two consecutive cladia. D. Hydrotheca. —

E-G. Solenoscyphus striatus gen. et sp. nov. E. Portion of stem with basal part of a side branch.

F. Hydrotheca, showing the characteristic striation of the perisarc. G. Operculum. Scale bars: A, C, E =

2 mm; B, D, F = 500 pm; G = 300 pm.

European Journal of Taxonomy 135: 1-19 (2015)

Table 2. Measurements of species of Solenoscyphus gen. nov., in pm.

S. candelabrum sp. nov.

S. decidualis sp. nov.

S. striatus sp. nov.

Stem

“Internode” length

1085-1235

830-925

1170-1445

Diameter at “node”

445-580

390M40

360-430

Cladial apophysis length

385M45

—

Cladium

“Internode” length

815-990

740-950

1170-1445

Diameter at “node”

445-580

220-340

360-430

First athecate internode

210-270

—

Hydrotheca

Adaxial side free

610-780

975-1085

950-1075

Adaxial side adnate

610-730

335-395

590-655

Abaxial side

1085-1185

1000-1075

1335-1420

Maximum width

—

420-445

Base width

—

295-335

Diameter at rim

315-355

280-300

430-450

both possibly originally parts of a single colony with multiple stems. This colony obviously fascicled

to an unknown extent, as largest available fragment comprises an accessory tube running up both

main stem and basal part of lowest side branch. Division into internodes indistinct; each equivalent of

internode relatively short, carrying a single hydrotheca on distal half. Branching pattern irregular and

sparing, with up to second order side branches given off laterally from below bases of hydrothecae; side

branches with same structure as stem; proximal-most intemode comparatively longer than following

ones. Hydrothecae biseriate and alternate; tubular in shape, adnate for slightly more than one-third of

adaxial length, facing up- and outward; abaxial wall almost straight, except for proximal part, which is

convex at point where hydrotheca becomes free on opposite side; free adaxial side straight and parallel

to adaxial counterpart. Apical part of hydrotheca distinctly swollen and there perisarc much thinner

than elsewhere; rim indistinctly tilted adaxially; rounded, thin operculum present in some hydrothecae;

point of attachment indeterminable; deciduous. External perisarc finely and densely striated over entire

colony. Gonothecae unknown; scar below one hydrotheca suggests at least one gonotheca was present

and subsequently lost; numerous large foramina (obliterated by thin pellicle of perisarc) indicate that

colony was about to become fertile.

Remarks

Although not resembling either S. candelabrum gen. et sp. nov. or S. decidualis gen. et sp. nov. in colony

shape, the present species nevertheless possesses a deciduous operculum, which is one of the main

features of the newly described genus.

Unlike S. candelabrum gen. et sp. nov., both S. decidualis gen. et sp. nov. and the present species possess

long, tubular hydrothecae with straight axes. However, their adnate parts are longer and their apertures

are wider in S. striatus gen. et sp. nov. Additionally, the entire perisarc of the latter is finely and densely

striated.

GAFEAH.R., New hydroids from New Caledonia

Family Syntheciidae Marktanner-Turneretscher, 1890

Genus Hincksella Billard, 1918

Key to species

The following key comprises all species currently included in the genus Hincksella.

1. Colonies pinnate.2

- Colonies with simple stems.5

2. Hydrothecae shallow . H. sibogae Billard, 1918

- Hydrothecae deep .3

3. Hydrotheca adnate for one-third. H. formosa (Fewkes, 1881)

- Hydrotheca adnate for half its length .4

4. Free part facing outward . H. alternans (Allman, 1888)

- Free part facing upward. H. Indiana Millard, 1967

5. Perisarc of hydrotheca finely and densely striated.6

- Perisarc of hydrotheca smooth or wr ink led .7

6. Hydrotheca making an almost right angle with the stem. H. similis sp. nov.

- Hydrotheca making an acute angle with the stem . H. neocaledonica sp. nov.

7. Perisarc of hydrotheca wrinkled. H. corrugata Millard, 1958

- Perisarc of hydrotheca smooth .8

8. Hydrotheca exceedingly long . H. pusilla Ritchie, 1910

- Hydrotheca moderately long .9

9. Aperture of hydrotheca facing outward . H. cornuta sp. nov.

- Aperture of hydrotheca facing upward .10

10. Hydrotheca isodiametric throughout . H. projecta (Fraser, 1938)

- Margin of hydrotheca distinctly flaring . H. rigida (Fraser, 1938)

Hincksella cornuta sp. nov.

urn:lsid:zoobank.org:act:5DC46422-9914-47FF-8CE3-49AB51B0014A

Fig. 5A-D; Table 3

Diagnosis

Stems simple, monosiphonic, nodes indistinct; intemodes relatively short, slightly geniculate, each

carrying a hydrotheca; the latter alternate, tubular, bent in middle; rim often renovated; gonothecae

arising from within the hydrothecae, broadly ovoid, lateral walls wrinkled; two prominent horns distally.

Etymology

From the Fatin, cornutus, meaning "homed", making reference to the prominent horns of the gono-

theca.

European Journal of Taxonomy 135: 1-19 (2015)

Material examined

Holotype

NEW CALEDONIA: campaign Bathus 4, station DW923, 18°52’ S, 163°24’ E, 502^70 m, 6 Aug.

1994; whole stem 3.6 cm high, bearing two fully-formed gonothecae (IK-2012-10297).

Paratypes

NEW CALEDONIA: data as for holotype, four specimens (3.1 cm high fragment with no basal part,

bearing two gonothecae; 3.3 cm high fragment devoid of its basal part; entire, 4.0 cm high stem with one

gonotheca; entire, sterile stem 3.8 cm high) (IK-2012-10298).

Description

Stems erect, up to 3.8 cm high, unbranched and monosiphonic, arising from tubular hydrorhizae; basal

constriction at origin from stolon; lower parts ahydrothecate and quite long (1.0-1.2 cm), occasionally

with signs of breakage and subsequent regeneration; perisarc smooth. Division by nodes indistinct, but

equivalents of internodes rather short, slightly geniculate, bearing single hydrothecae on distal halves.

Hydrothecae alternate, although the two proximal-most ones may be given off on same side of stem;

Fig. 5. — A-D Hincksella cornuta sp. nov. A. Basal portion of stem with hydro- and gonothecae.

B. Hydrotheca. C. Detail of the foramen for the passage of the hydranth into hydrotheca. D. Gonotheca

arising from within a hydrotheca. — E-F. Hincksella neocaledonica sp. nov. E. Portion of stem.

F. Hydrotheca, showing outer striations. — G-H. Hincksella similis sp. nov. G. Portion of stem.

H. Hydrotheca, showing extent of external striations. Scale bars: A, E, G = 1 mm; B, D, F, H = 500 pm;

C = 200 pm.

GALEA H.R., New hydroids from New Caledonia

tubular, adnate for less than half of length; free part facing out- and upward; free adcauline wall slightly

convex to almost straight; abcauline wall convex in middle and straight elsewhere; basal foramina

with multiple renovations of perisarc (Fig. 5C); rim of hydrotheca often renovated; aperture circular,

imperceptibly tilted adaxially. Hydranths enveloped by inner, thin, collapsible periderm, distinct from

hydrothecal wall; tentacle number could not be counted. Gonothecae given off from within hydrothecae;

broadly ovoid, with wrinkled perisarc, distally with two prominent horns; no signs of aperture;

gonophore apparently single, large ovoid mass (oocyte?) occupying nearly entire lumen of gonotheca.

Large macrobasic heteronemes (none seen discharged), with parallel walls and rounded ends, and with

straight or slightly curved longitudinal axes, occur abundantly in coenosarc.

Remarks

The alternate, long, tubular, non-operculate hydrothecae, the gonothecae given off from within the

hydrothecae, as well as the large macrobasic heteronemes (mastigophores?) scattered in the coenosarc

place this species in the genus Hincksella Billard, 1918. The two horns on the distal part of its gonothecae

distinguish this species from its congeners with known gonosomes, viz. H. alternans (Allman, 1888)

(see original description), H. formosa (Fewkes, 1881) (see Galea 2013), H. pusilla Ritchie, 1910 (see

Galea & Ferry 2015), and H. sibogae Billard, 1918 (see Vervoort & Watson 2003).

The remaining congeners with unknown gonothecae differ from H. cornuta sp. nov. in the following

respects: 1) H. corrugata Millard, 1958 has comparatively shorter hydrothecae, adnate for as much

as half their length, and their surface is transversely wrinkled (Millard 1958); 2) H. indiana Millard,

1967 is a much larger species, with fascicled stems, shorter hydrothecae, conspicuously tilted adaxially

(Millard 1967); 3) the poorly described H. projecta (Fraser, 1938) appears to be different due to the

lower length/width ratio of its hydrothecae, as well as on biogeographical grounds (Fraser 1938); 4) the

hydrothecae of H. rigida (Fraser, 1938) are nearly as broad as deep and, according to Fraser (1938), they

are comparatively shorter.

Hincksella neocaledonica sp. nov.

urn:lsid:zoobank.org:act:69FDB75D-8E59-4CFB-9387-35B0ClBlD65F

Fig. 5E-F; Table 3

Diagnosis

Stems simple, monosiphonic, divided into rather long internodes, each bearing a hydrotheca; the latter

alternate, long, tubular, facing out- and upward; rim often renovated; surface of hydrotheca densely and

finely striated.

Etymology

Named for its area of occurrence. New Caledonia.

Material examined

Holotype

NEW CALEDONIA: campaign Biocal, station DW46, 22°53’ S, 167°17’E, 570-610 m, 30 Aug. 1985;

2.5 cm high, infertile stem devoid of hydrorhiza (IK-2012-10299).

Description

The 2.5 cm high stem fragment is devoid of its hydrorhiza and seems to have been broken off just

above its origin from it. Monosiphonic throughout and unbranched; very basal part ( ca . 2.5 mm long)

ahydrothecate; remainder of stem divided into 21 moderately long, slender and geniculate internodes.

European Journal of Taxonomy 135: 1-19 (2015)

Table 3. Measurements of new species of Hincksella Billard, 1918, in pm.

H. cornuta sp. nov. H. neocaledonica sp. nov. H. similis sp. nov.

Stem

“Internode” length

1160-1915

925-1420

665-1110

Diameter at “node”

310-370

150-215

185-290

Hydrotheca

Adcauline side free

865-915

680-740

790-1000

Adcauline side adnate

590-730

395M20

465-490

Abcauline side

1135-1270

900-1010

1010-1235

Diameter at rim

345-370

275-300

290-320

Gonotheca

Length

1245-1355 (w/o spines)

1395-1455 (w/ spines)

—

Maximum width

655-730

—

Cnidome

Large capsules

(17.5-20.3) x (5.7-6.8)

(17.5-19.3) x (57-6.4)

(15.0-16.8) x(5.4-6.1)

by means of transverse nodes; perisarc of internodes smooth; a distally-placed hydrotheca per internode.

Hydrothecae alternate, tubular, adnate for one-third of adcauline length, facing up- and outward, and

oriented at an angle of c. 45° with internode; free adcauline wall nearly straight to imperceptibly convex;

abcauline wall convex at inflexion point, then straight and parallel to its free adcauline counterpart;

perisarc of hydrotheca finely and densely striated throughout; rim often renovated; aperture circular,

perpendicular to long axis of hydrotheca. Gonotheca unknown. Large, parallel-walled macrobasic

heteronemes (none seen discharged), with either straight or slightly curved axes and rounded ends,

co mm on in coenosarc.

Remarks

The alternate, long, tubular, non-operculate hydrothecae and the large nematocysts scattered in the

coenosarc place this species, with little doubt, in the genus Hincksella Billard, 1918. It superficially

resembles H. pusilla (Ritchie, 1910) (see Galea & Ferry 2015 for taxonomical considerations) through

the shape of its internodes and hydrothecae. However, Ritchie’s species is comparatively smaller (Galea

2010: table 3) and the perisarc of its hydrothecae is smooth throughout.

Hincksella similis sp. nov.

urn:lsid:zoobank.org:act:DBF94D6B-02BA-4364-B599-A411A95D8EC5

Fig. 5G-H; Table 3

Diagnosis

Stems simple, monosiphonic; nodes indistinct; each internode with a distal hydrotheca; the latter long,

tubular, distinctly facing outward, finely and densely striated on free adcauline wall and lower part of

abcauline wall.

Etymology

From the Latin similis , meaning "similar", on account of its resemblance to H. pusilla Ritchie, 1910.

GALEA H.R., New hydroids from New Caledonia

Material examined

Holotype

NEW CALEDONIA: campaign Norfolk 1, station DW1722, 23°18’ S, 168°10’ E, 540 m, 26 Jun. 2001;

sterile, 2.2 cm high stem (IK-2012-10300).

Description

Colony erect, 2.2 cm high, arising from creeping, tortuous, branching stolon. Stem monosiphonic,

unbranched; basal part 9 mm long, ahydrothecate; remainder of stem divided by means of indistinct

nodes; each equivalent of internode rather short, slightly geniculate to almost collinear, each bearing a

hydrotheca distally. Hydrothecae tubular, given off at an angle of c. 65-70° with internode, long axis

slightly sigmoid; abcauline wall markedly curved where hydrotheca becomes free; aperture rounded,

rim even, slightly flared; renovations occasional; perisarc of hydrotheca finely and densely striated,

especially on free adcauline side and proximal part of abcauline wall. Gonotheca unknown. Large

macrobasic heteronemes (none seen discharged), with parallel walls and rounded ends, and with straight

or slightly curved longitudinal axes, occur abundantly in coenosarc.

Remarks

The alternate, long, tubular, non-operculate hydrothecae and the large nematocysts scattered in the

coenosarc place this species, with little doubt, in the genus Hincksella Billard, 1918. This species

resembles both H. pusilla Ritchie, 1910, through the shape of its hydrothecae, and H. neocaledonica

sp. nov. through their striations. However, the former is a much smaller species (see dimensions in Galea

2010: table 3), while the latter has comparatively longer and more geniculate internodes, its hydrothecae

are given off at more acute angles, their free part is shorter, and the striations extend over the whole

perisarc of the colony.

Acknowledgements

I am indebted to Philippe Bouchet and Pierre Lozouet, both of MNHN, for giving me access to the

material described in this work. I am grateful to Dale Calder (Royal Ontario Museum, Toronto, Canada)

for unhesitatingly giving his best advice on some systematic issues dealt with in the present work, as

well as for providing useful suggestions related to subtleties of English wording. Thanks are also due

to two anonymous reviewers for comments on an earlier version of this work. Gratitude is extended to

Danny Eibye-Jacobsen (Zoological Museum, Natural History Museum of Denmark, Copenhagen) for

handling the editing. This study was undertaken with no financial support.

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Manuscript received: 13 May 2015

Manuscript accepted: 17 June 2015

Published on: 31 August 2015

Topic editor: Rudy Jocque

Desk editor: Danny Eibye-Jacobsen

Printed versions of all papers are also deposited in the libraries of the institutes that are members of

the EJT consortium: Museum National d’Histoire Naturelle, Paris, France; Botanic Garden Meise,

Belgium; Royal Museum for Central Africa, Tervuren, Belgium; Natural History Museum, London,

United Kingdom; Royal Belgian Institute of Natural Sciences, Brussels, Belgium; Natural History

Museum of Denmark, Copenhagen, Denmark.