Two New Genera and Species of Ophiuroid (Echinodermata) from Hydrothermal Vents in the East Pacific

Abstract

Prior to this study, two species of ophiuroid had been described from hydrothermal vent sites, and another from methane cold seeps, all from the Atlantic Ocean. Although ophiuroids have occasionally been reported from vents in the Pacific Ocean as well, none has been described before. This study presents two new species, Spinophiura jolliveti gen. et sp. nov., family Ophiuridae, and Ophiolamina eprae gen. et sp. nov., family Ophiacanthidae, which are most likely endemic to reducing environments in the East Pacific. We also include detailed descriptions of the post-metamorphic development of these species. Spinophiura jolliveti is characterized by up to five rather long, semi-erect arm spines and a relatively small oral shield. Its postlarva is unusual in lacking a buccal scale and in that the tooth forms later in development than in all other species the postlarvae of which have been examined. The most characteristic features of O. eprae are the attitude of the three proximal laminar mouth papillae, standing almost vertically on the oral plate, and the presence of two oval, scale-like, distal papillae. Additional migrant (non-vent-endemic) species found at Pacific vent sites are tabularized, but not identified below genus level due to the poor taxonomic state of the Pacific ophiuroid fauna. Biogeographic and ecological issues are discussed.

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Species Diversity
February 2006; Volume 11 (1) : Pages 7-32
© 2006 The Japanese Society of Systematic Zoology
Archimer
Archive Institutionnelle de l’Ifremer
http://www.ifremer.fr/docelec/
Two New Genera and Species of Ophiuroid (Echinodermata) from
Hydrothermal Vents in the East Pacific
Sabine Stöhr1, * and Michel Segonzac2
1 Swedish Museum of Natural History, Department of Invertebrate Zoology, Frescativ. 40, Box 50007, 10405
Stockholm, Sweden
2 IFREMER, Centre de Brest, DEEP/Laboratoire Environnement profond-Centob, BP 70, 29280 Plouzané, France
*: Corresponding author : S. Stöhr, email address : sabine.stohr@nrm.se
Abstract:
Prior to this study, two species of ophiuroid had been described from hydrothermal vent sites, and
another from methane cold seeps, all from the Atlantic Ocean. Although ophiuroids have occasionally
been reported from vents in the Pacific Ocean as well, none has been described before. This study
presents two new species, Spinophiura jolliveti gen. et sp. nov., family Ophiuridae, and Ophiolamina
eprae gen. et sp. nov., family Ophiacanthidae, which are most likely endemic to reducing
environments in the East Pacific. We also include detailed descriptions of the post-metamorphic
development of these species. Spinophiura jolliveti is characterized by up to five rather long, semi-
erect arm spines and a relatively small oral shield. Its postlarva is unusual in lacking a buccal scale
and in that the tooth forms later in development than in all other species the postlarvae of which have
been examined. The most characteristic features of O. eprae are the attitude of the three proximal
laminar mouth papillae, standing almost vertically on the oral plate, and the presence of two oval,
scale-like, distal papillae. Additional migrant (non-vent-endemic) species found at Pacific vent sites are
tabularized, but not identified below genus level due to the poor taxonomic state of the Pacific
ophiuroid fauna. Biogeographic and ecological issues are discussed.
Keywords: Brittle stars, postlarval development, Ophiuridae, Ophiacanthidae, SEM, morphology,
taxonomy, hydrothermal vent, cold seep.

1. Introduction
Deep-sea hydrothermal vents are found along all mid-ocean ridges and form an
ecosystem based on bacterial chemosynthesis (Van Dover 2002). Vents have been
studied intensively since their discovery in 1977 and they harbour a unique invertebrate
fauna with specific adaptations to the thermal and chemical conditions that prevail
there (Tyler et al. 2003). Similar ecosystems are found at methane cold seeps and
around whale skeletons. Despite the fact that echinoderms dominate the errant
megafauna on the deep-sea floor (Gage and Tyler 1991), few species occur at
hydrothermal vents and seeps, and none has yet been found on whale skeletons
(Smith et al. 2002). Ophiuroids were largely unknown in these environments until
recently. Hecker (1985) reported ophiuroids from cold seeps, but they remain
undescribed. A decade ago, the first vent- or seep-inhabiting ophiuroid species,
Ophioctenella acies Tyler et al., 1995, was described from the TAG (Trans-Atlantic
Geotraverse), Snake Pit, and Broken Spur vent fields on the Mid-Atlantic Ridge (MAR)
(Tyler et al. 1995). Since then, Ophiactis tyleri Stöhr and Segonzac, 2005 has been
described from the Menez Gwen vent field on the MAR, but it remains to be seen
whether this species is restricted to vent localities, and Ophienigma spinilimbatum
Stöhr and Segonzac, 2005 has been found at seeps in the Gulf of Mexico, and is likely
endemic to these sites (Stöhr and Segonzac 2005). Ophiuroids have been reported
occasionally from vent sites in the Pacific Ocean (Sibuet and Olu 1998; Halanych et al.
1999), but none has been described. Describing new species from the Pacific Ocean is
problematic, because the ophiuroid fauna of the Pacific is not as well-studied as that of
the Atlantic Ocean. The literature is scattered, difficult to access, often outdated, and
occasionally employs multiple names for the same morphological species. A first
attempt at revising part of the Pacific ophiuroid fauna resulted in a large number of
synonymisations and the description of several new species (O’Hara and Stöhr in
press).
In this paper we report on the ophiuroids found at hydrothermal vents and cold seeps
on the East Pacific Rise (EPR; Fig. 1), Easter Microplate, and Pacific-Antarctic Ridge,
and in the Manus Back-Arc Basin (N off Papua New Guinea) and Nankai Trough (S off
Tokyo), and describe the first two species of ophiuroid endemic to vent environments in
the Pacific. The material includes individuals of different ontogenetic stages and thus
allows the analysis and detailed description of the post-metamorphic development of
both species. Juveniles have been described for probably no more than 50 species of
ophiuroid (Stöhr 2005 and literature cited therein) and additional data are important for
understanding the phylogenetic relationships between taxa. Accurate descriptions of
juveniles may also serve as a tool for ecologists, since most identification keys are
based on adult characters.
2. Materials and Methods
During several different cruises (Table 1), ophiuroids were collected by using a slurp
gun, a scoop, or a grab from submersibles and remotely operated vehicles (ROV). An
exception to this were the samples collected by the SEPR (South East Pacific Rise)
cruise under supervision of C. Van Dover using the manned submersible Alvin (Table
1). On that cruise a quantitative collecting method was employed featuring specially
designed pots, which reduced the loss of associated organisms (Van Dover, pers.
comm.).
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Samples were washed, preserved in formalin, and later transferred to 80% ethanol.
Selected specimens were submerged in household bleach (NaOCl diluted with water
1:1) for 10 to 30 seconds, depending on the size of the specimen, to remove the
epidermis and expose the skeleton. Skeletal elements were prepared by treating a
specimen with undiluted household bleach until all soft tissues had disappeared. The
specimens were then washed in water, dried, and mounted on aluminium stubs for
scanning electron microscopy (SEM). As adhesive, a non-permanent spray glue was
used. Small specimens were mounted wet on the glue and left to dry. To scan both
sides of an animal, most of the glue was dissolved in butyl acetate and its residue
brushed off, and then the specimen was remounted with fresh glue. The glue could not
always be completely removed from small specimens due to the risk of damage from
the mechanical stress, of the fine brush. After coating with gold, the specimens were
examined with a Hitachi FE-4300 SEM. Size measurements were taken off the
instrument’s scale bar or, with large specimens, by using a dissecting microscope fitted
with an ocular micrometer. The size of a specimen (spm) is given as disk diameter
(dd).
Juveniles were matched to adults of the same species by tracing skeletal characters
backwards through the growth series, a method successfully applied in previous
studies (Sumida et al. 1998; Stöhr 2005). The terminology used follows Sumida et al.
(1998) and the classification follows Smith et al. (1995). Type material has been
deposited at the Swedish Museum of Natural History, Stockholm (SMNH); the National
Museum of Natural History, Smithsonian Institution, Washington DC (USNM); and the
Muséum National d’Histoire Naturelle, Paris (MNHN), as indicated below. All non-type
material has also been deposited at the MNHN.
3. Results
All specimens of ophiuroids found on the EPR belong to two families, Ophiuridae and
Ophiacanthidae (Table 2). The most abundant species (270 individuals) is new to
science and described below as Spinophiura jolliveti gen. et sp. nov. (Fig. 2), family
Ophiuridae. The post-metamorphic development of the species is described in detail
(Figs 3, 4). The second most common species (31 individuals) is described below as
Ophiolamina eprae gen. et sp. nov., family Ophiacanthidae (Fig. 6). A growth series of
this species was also available to use in describing its postmetamorphic development
(Figs 7, 8). Neither of these species has so far been found in non-reducing
environments. The species found at the Nankai Trough cold seep sites and other
species at vents, of which single or few individuals were found, are most likely bathyal
species and belong to the families Ophiuridae and Ophiacanthidae. These species are
documented in Table 2 for later reference.
Spinophiura jolliveti and Ophiolamina eprae have been found sympatrically at four vent
sites in roughly the same area between 17°25’S and 18°36’S (Table 2). Ophiolamina
eprae was also found at 12°48’N (type locality), but not between this locality and the
southern area. Spinophiura jolliveti was found between 9°N and 38°S. Both species are
absent at the Manus Basin vent field and are probably restricted to the EPR. Farther to
the north and south single specimens of other species were found.
4. Taxonomic account
Family Ophiuridae Lyman
Genus Spinophiura new genus
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Diagnosis. As for type species.
Etymology. The genus name is composed of spin(a) from Latin for ‘spine’, and
Ophiura, to indicate its affinities with that genus; gender feminine.
Type species. Spinophiura jolliveti sp. nov.
Description. As for type species.
5. Spinophiura jolliveti sp. nov.
(Figures 2-4, 5A-C)
Holotype. 10 mm dd, dry, MNHN EcOs 22635.
Type locality. Cruise HOPE 99, Nautile, dive PL 1372, 3 May 1999, EPR-9°N,
hydrothermal vent site Biovent, 09°50.52’N, 104°17.62’W, 2518 m.
Paratypes. For all station data see Table 2. Growth series of 20 spms mounted on
SEM stubs and gold-coated: 13 spms, BIOSPEEDO, PL 1585, 26 Apr 2004, SMNH-
Type-6052-6059, 6076; 7 spms, BIOSPEEDO, PL1590, 1 May 2004, SMNH-Type-
6060-6066; 4 spms, dry, BIOSPEEDO, PL 1585, basket 1, 26 Apr. 2004, MNHN EcOs
22636. Samples in ethanol (80% unless stated otherwise): 1 spm, SEPR, dive 3343,
Sample 1, 2 Feb. 1999, USNM 1078905; 2 spms, SEPR, dive 3349, 8 Feb. 1999,
USNM 1078906; 1 spm, SEPR, dive 3358, Sample B-6, 19 Feb. 1999, USNM
1078907; 3 spms, SEPR, dive 3489, Pot 4, 17 Nov. 1999, USNM 1078908; 1 spm,
SEPR, dive 3489, Pot 5, 17 Nov. 1999, USNM 1078909; 1 spm, SEPR, dive 3489, Pot
2, 17 Nov. 1999, USNM 1078910; 2 spms (1 small postlarva, 1 adult), SEPR, dive
3490, Grey box, 18 Nov. 1999, USNM 1078911; 1 spm, SEPR, dive 3490, Pot 6, 18
Nov. 1999, USNM 1078912; 1 spm, SEPR, dive 3740, 26 Dec. 2001, USNM 1078913;
13 spms, PAR 5, dive 4091, 25 Mar. 2005, USNM 1078914; 1 spm, PAR 5, dive 4094,
28 Mar. 2005, USNM 1078915; 3 spms, 95% ethanol, BIOSPEEDO, PL 1583, basket
1, 23 Apr. 2004, MNHN EcOh 20000; 12 spms, BIOSPEEDO, PL 1583, basket 1, 23
Apr. 2004, MNHN EcOh 20001; 7 spms, 95% ethanol, BIOSPEEDO, PL 1585, basket
1, 26 Apr. 2004, MNHN EcOh 20002; 5 spms, 95% ethanol, BIOSPEEDO, PL 1585,
BC4, 26 Apr. 2004, MNHN EcOh 20003; 103 spms, BIOSPEEDO, PL 1585, basket 1,
26 Apr. 2004, MNHN EcOh 20004; 1 spm, BIOSPEEDO, PL 1587, basket 1, 28 Apr.
2004, MNHN EcOh 20005; 1 spm, BIOSPEEDO, PL 1590, ‘Alvinette’ box, 1 May 2004,
MNHN EcOh 20006; 3 spms, HOPE 99, PL 1372, slurp gun 1, 3 May 1999; MNHN
EcOh 20007; 1 spm, HOPE 99, PL 1372, slurp gun 2, 3 May 1999, MNHN EcOh
20008; 3 spms, HOPE 99, PL 1375, basket 4, 6 May 1999, MNHN EcOh 20009; 1 spm
(postlarva), HOPE 99, PL 1377, basket, 8 May 1999, MNHN EcOh 20010; 14 spms,
NAUDUR, ND06-2, 11 Dec. 1993, MNHN EcOh 20011; 1 spm, NAUDUR, ND12, 17
Dec. 1993, MNHN EcOs 20012; 2 spms, HOT 96, PL1073, basket 2, 25 Feb. 1996,
MNHN EcOh 20013; 2 spms (postlarvae), HOT 96, PL1078, basket 1, 7 Mar. 1996,
MNHN EcOh 20014; 1 spm, HOT 96, PL 1090, basket 1, 20 Mar. 1996, MNHN EcOh
20015; 1 spm, PHARE, PL167, basket 1, 29 May 2002, MNHN EcOh20016; 1 spm,
PHARE, PL 164, slurp gun 4, 25 May 2002, MNHN EcOh 20017; 1 spm, Hero 91, PL
614, 13 Oct 1991, MNHN EcOh 20018; 5 spms, HOPE 99, PL 1386, 7 May 1999,
SMNH-Type-6106; 42 spms, BIOSPEEDO, PL 1590, 01 May 2004, SMNH-Type-6107.
Diagnosis. The species reaches a dd of up to 10 mm. Distinct arm combs continue
across the arm base. There are up to five semi-erect arm spines, which are longer than
an arm joint. The mouth papillae are spine-like, numbering 10-14 to one side of a jaw.
The first tentacle pore in the mouth slit bears one to three spine-like papillae. The oral
shield is just over a third as long as the ventral disk. The up to seven tentacle scales
are spine-like.
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Etymology. The species is named in honour of Didier Jollivet for his accomplishments
in studying hydrothermal vent communities.
Description of holotype. The disk measures 10 mm in diameter, and arm length is
about 50 mm. The arms rapidly taper, and are whip-like and curled (Fig. 2A). The
dorsal disk is formed by numerous round, overlapping scales, among which the
primary plates are not obvious. The radial shields are a little longer than wide, their
length being about one sixth of dd, and they are partly covered proximally by scales;
pairs are separated by a wedge-like plate except at their distal ends (Fig. 2C). Below
each radial shield there is a distinct arm comb, which continues across the arm. Part of
the distal end of the genital plate is visible beneath the radial plate with which it
articulates. The comb papillae are pointed, flat, and spine-like. The arm is inserted into
the disk with a short incision between the radial plates. The first dorsal arm plate is
much smaller than the following plates and is partly covered by the disk, bearing a few
short papillae. Each lateral arm plate bears four to five flat, pointed, slightly rugose
spines, which are slightly longer than an arm joint. Distalwards the spines become
increasingly thorny, and the distalmost spines are curved with a thorny inner edge. The
dorsal arm plates are contiguous and trapezoidal, with a convex distal edge, their
greatest width being about equal to their length.
The ventral disk is formed by small, round, overlapping scales (Fig. 2B). The bursal slit
is lined along its proximal half with round, overlapping scales, along its distal half with a
long genital scale, which extends around the arm and articulates with the radial shield.
On the outer edges of these scales and plate, a row of pointed genital papillae runs
from the edge of the oral shield to the dorsal side (Fig. 2D), where it forms the arm
comb. The dental plate bears six teeth. There are 10-14 long, slender and pointed,
spine-like papillae to either side of a jaw, three of them on the dental plate, three to four
on the oral plate, and four to seven on the edge of the adoral shield. Inside the mouth
slit on the vertical side of the oral plate at the edge of the first tentacle pore, one to
three slightly smaller but otherwise similar spine-like papillae stand out. The second
tentacle pore is superficial and covered by the mouth papillae and additional similar
papillae, two to three on the first lateral arm plate and one to two on the first ventral
arm plate. The oral shield is shaped like a short arrow, about as long as its greatest
width, and at 1 mm it is just a little over a third as long as the interradial ventral disk
(Fig. 2D). One oral shield is larger than the others, swollen and with less pronounced
lateral angles, and bearing a pore on the lateral edge next to the bursal slit (not visible
in image); this is the madreporite. The adoral shields are narrow and curve around the
lateral angles of the oral shield. The first lateral arm plate curves vertically into the
mouth angle so that only its distal edge bearing the papillae is visible next to the
second tentacle pore.
The first ventral arm plate is depressed in its centre and its proximal edge is turned
down into the mouth slit. It is smaller than the following plates. On the proximal part of
the arm, the ventral plates are about twice as wide as long, with concave proximal and
distal edges. Neighbouring plates are separated by the lateral arm plates, which do not
meet. Instead, a small area of unscaled skin can be seen between the plates. At the
third tentacle pore, there are six to seven spine-like scales, similar to the mouth
papillae, three on the edge of the ventral plate and four on the lateral plate. The fourth
tentacle pore bears six scales, two on the ventral plate and four on the lateral plate. At
the fifth pore there are five to six scales, at the sixth pore five scales; numbers
decrease distalwards along the arm. Beyond the disk margin, the ventral arm plates
become pentagonal, with an obtuse proximal angle, a concave or notched distal edge,
and inward-slanting lower lateral edges. On the distal part of the arm, the ventral plates
are longer than wide and neighbouring plates almost meet. The lateral arm plates
extend onto the ventral side of the arm along the proximal edge of the ventral plate, but
do not meet.
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The live coloration of this species is a light beige to cream. The majority of the
specimens collected were smaller than the holotype, which is one of the largest adults.
Paratype variation. Only two specimens are as large as the holotype, and those are
morphologically similar to the latter. Many of the paratypes of 8-9 mm dd lack the
cluster of papillae on the first arm plate connecting both combs. In any single animal,
considerable variation exists in the number of mouth papillae between different jaws as
is described above for the holotype. Differences between individuals of different size
are due to differences in ontogenetic stage as is explained below.
Post-metamorphic development (paratypes). The smallest postlarva found
measures 0.4 mm in dd, with arms consisting only of the terminal plate. The dorsal disk
is formed by the central primary plate and five radial primary plates, all with an irregular
meshwork of fenestrations, multilayered in the centre and single-layered on the margin
(Fig. 3A). The bulging first lateral arm plates (= adoral shields) are visible beyond the
disk margin at the base of each terminal plate. No oral shields or madreporite are
present. The jaws are formed by the two oral plates and the dental plate, which does
not bear a tooth (Fig. 3B). The first ventral arm plate is arrow-shaped and flanked by
large tentacle pores. The adoral shields each bear a short, tapered spine with minute
thorns along its edges. The terminal plate has ribs bearing minute thorns along its
length and ends in a ventral opening and several terminal thorns (Fig. 3C).
At 0.8 mm dd and four arm joints in addition to the terminal plate, the dorsal disk is
formed by the primary plates and small interradial plates (Fig. 3D). The radial shields
have just begun to form distal to the radial primary plates, and the proximal arm joint
bears a small, triangular dorsal plate. A minute tooth has formed on the dental plate
and the oral shields are just visible at the disk edge (Fig. 3E). Ventral plates have
formed on the three proximal arm joints, decreasing in size distalwards on the arm. The
lateral plates bear two conical spines each except at the fourth joint, which is just
beginning to form and bears a single short spine. The adoral shield spine points
outwards and is visible from the dorsal side.
At 1.0 mm dd, the arm consists of eight joints and the terminal plate, although the distal
two joints are only just beginning to form. In addition to the primary plates, short radial
plates and a large distal and small proximal interradial plate are present (Fig. 3F).
Dorsal arm plates are present on three arm joints, the first one oval, the second drop-
shaped, and the third triangular. The tooth has grown and a small mouth papilla has
formed on the oral plate (Fig. 3G). The oral shields are clearly visible at the disk edge
between the adoral shields, but the madreporite is not distinguishable. The first ventral
arm plate is elongate-pentagonal, with a convex distal edge and concave lateral edges.
Distalwards along the arm this shape is less and less pronounced.
At 1.3 mm dd, a few secondary interradial plates have formed distal to the central
primary plate and a k-plate is visible on some radii at the proximal end of the radial
shields (Fig. 3H). The first dorsal arm plate is oval, while the others are drop-shaped
and separate. On some oral plates, an additional granule-like lateral mouth papilla has
formed (Fig. 3I). The adoral shield spine has shortened and a minute papilla has
formed on the lateral edge of the first ventral arm plate next to the second tentacle
pore, which has moved closer to the mouth slit. The lateral arm plate bears a short,
spine-like tentacle scale and proximally three (distally two) spines, about half as long
as an arm joint.
At 1.8 mm dd, all k-plates are present and additional interradial plates have formed
(Fig. 4A). Three to four genital papillae form the arm comb. The proximal arm joints
bear three spines.
At 2.1 mm dd, additional interradial plates have formed (Fig. 4B). There are two to
three mouth papillae at each jaw edge, at least one of them on the oral plate; some
jaws have one, others two papillae on the dental plate (Fig. 4C). The adoral shield
bears two larger papillae and opposite to them the first ventral arm plate bears two
6

smaller papillae, all four pointing at each other across the second tentacle pore. The
oral shield has its final, arrow-like shape.
The number of disk scales and mouth, tentacle, and genital papillae increases during
further growth. At 3.1 mm dd, the second tentacle pore has moved to its final position
at the mouth slit, framed by five to six papillae (Fig. 4D). Each jaw edge bears three to
four papillae.
At 5 mm dd, the animals show adult characters, although the shape of some skeletal
elements still differs from those of the largest adults. In addition to the outer arm comb
on the distal genital plate, a short inner comb has formed of a few papillae on the first
and second dorsal arm plates (Fig. 4F). These papillae fill the gap between the genital
plates and give the appearance of a continuous comb across the arm base. Of the four
arm spines on the proximal arm, the dorsalmost is twice as large as the others. The
dorsal arm plates are longer than wide on all but the most proximal segments. The
mouth papillae have become elongated, spine-like, and more numerous (Fig. 4E). The
maximum size observed was10 mm dd.
Comparisons. The dorsal disk and arms of S. jolliveti are similar to those of Ophiura
species, but the long, spine-like shape of the mouth papillae and tentacle scales is
unknown in that genus. Also, the oral shield is rather small compared to that of
Ophiura. The number of arm spines increases during ontogeny, and since the
ontogenetic stage of an individual may be unknown unless complete growth series are
available, arm spine number is a character that must be used with caution. The growth
series of S. jolliveti suggests that the final number of arm spines is five. Many species
of Ophiura possess three to five arm spines, but these are usually much shorter than
an arm joint and appressed (Lyman 1878; Clark 1911, 1915, 1917). The presence of
tentacle scales on the first tentacle pore inside the mouth slit has not been described
for any other species of ophiuroid, but in the ophiacanthid Ophiomyces Lyman, 1869, a
scale-like papilla is present at the first tentacle pore, although this is an overlooked and
unreported feature (F. Hotchkiss, pers. comm.).
The ontogeny of S. jolliveti is similar to that of Ophiura, but a buccal scale is absent in
the small postlarvae of this species and the first tooth forms quite late during
development. In all analyzed species of Ophiura, both the first tooth and the buccal
scale are present in the earliest stage (Sumida et al. 1998; Stöhr 2005). It is unclear
which condition is plesiomorphic. The madreporite in the present species cannot be
distinguished from the oral shields until almost the adult stage, and all oral shields
develop later than in many other species (Sumida et al. 1998; Stöhr 2005). During
development, some parts of these pentamerous animals develop faster than others,
which produces an asymmetrical pattern at some stages, e.g., k-plates on some but
not all radii. In particular, the development of the mouth papillae differs between jaws
and the final number of papillae in the adult is different on different jaws.
Spinophiura jolliveti shares some characters with Ophiura and may be a modified
representative of that genus, but the striking differences also merit a taxonomic
separation, at the risk of leaving Ophiura paraphyletic. We thus propose a new genus,
which may be re-evaluated when the relationships of the species and its origin are
better understood.
Habitat and distribution. Spinophiura jolliveti was found only at vents. The large
number of specimens collected (270) suggests that this species is adapted to
hydrothermal environments. It is present at several vent sites on the EPR at 9°N
(Barbecue, Mussel Bed, East Wall, and Train Station), 13°N (Genesis, Parigo, Julie,
and Grandbonum), 17°25'S (Oasis-Rehu), 17°35'S (Wormwood), and 18°36'S (Animal
Farm). The structure, abundance, and composition of the animal communities living at
these sites are different, but several related invertebrate species are shared by the
northern and southern sites (Geistdoerfer et al. 1995). Spinophiura jolliveti is generally
associated with the mytilid bivalve Bathymodiolus thermophilus Kenk and Wilson, 1985
7

(more rarely with the vesicomyid clam Calyptogena magnifica Boss and Turner, 1980),
living in the hydrothermal fluid where the temperature varies between 2°C and 15°C
(Fig. 5A). Large clouds of amphipods were often observed above these mussel beds
during the collecting dives. The mussel populations on which these ophiuroids live are
sometimes composed of a high number of dead individuals (Van Dover, unpublished
data), which may indicate a necrophagous habit. At the northern sites [9°N
(Chevaldonné et al. 1995) and 13°N], the ophiuroids are found in the same
environments as the siboglinid tubeworms Riftia pachyptila Jones, 1981 (Fig. 5B, C),
crabs Bythograea thermydron Williams, 1980, galatheid crabs Munidopsis
subsquamosa Henderson, 1885, hippolytid shrimps Lebbeus White, 1847, and zoarcid
fishes Thermarces cerberus Rosenblatt and Cohen, 1986. At the southern sites, these
same megafaunal species are present, but in addition, there are holothurians Chiridota
hydrothermica Smirnov et al., 2000, turrid gastropods Eosipho auzendei Warén and
Bouchet, 2001, ophidiid fishes, and high densities of actinostolid sea anemones
Chondrophellia Carlgren, 1925 and stalked barnacles Neolepas Newman, 1979. The
relationships between these species and the ophiuroids are not understood yet, but
waste products produced by them may provide a food source for the ophiuroids or
some species may be predators of ophiuroids.
Family Ophiacanthidae s. l. Perrier
Genus Ophiolamina new genus
Diagnosis. As for type species.
Etymology. The genus name is composed of Ophio, the commonly accepted form for
most ophiuroid genera, from Greek ‘like a snake’, and Latin lamina ‘thin plate, blade,
layer’, gender feminine. This name refers to the blade-like mouth papillae of the type
species.
Type species. Ophiolamina eprae sp. nov.
Description. As for type species.
6. Ophiolamina eprae sp. nov.
Figures 5D, E-8
Holotype. 3.7 mm dd, dry, mounted on SEM stub, gold-coated, MNHN EcOs 22637.
Type locality. Cruise PHARE, ROV Victor 6000, dive PL 155, 10 May 2002, slurp gun
2, EPR-13°N, marker PP52, hydrothermal vent site Genesis, 12°48.69’N, 103°56.36’W,
2592 m.
Paratypes. Specimens on SEM stubs, gold coated: 3 spms, BIOSPEEDO, PL 1585,
26 Apr. 2004, SMNH-Type-6108; 2 spms BIOSPEEDO, PL 1590, 1 May 2004, SMNH-
Type-6109; 5 spms, SEPR, dive 3349, 8 Feb. 1999, SMNH-Type-6110, 6111; 1 spm,
type locality, MNHN EcOs 22638; skeletal elements, type locality, MNHN EcOs 22639,
22640. Specimens in alcohol (80%): 4 spms, type locality, MNHN EcOh 20019; 1 spm,
BIOSPEEDO, PL 1579, 19 Apr. 2004, MNHN EcOh 20020; 6 spms (postlarvae) SEPR,
dive 3349, sample 5, 8 Feb. 1999, USNM 1078916; 3 spms (postlarvae) SEPR, dive
3349, sample 1, 8 Feb. 1999, USNM 1078918; 1 spm (postlarvae) SEPR, dive 3349,
sample 4, 8 Feb. 1999, USNM 1078919; 1 spm (postlarva), SEPR, dive 3727, 14 Dec.
2001, USNM 1078920; 2 spms, PAR 5, dive 4097, 31 Mar. 2005, USNM 1078921. For
station data see Table 2.
Diagnosis. This is an ophiacanthid ophiuroid of up to 3.5 mm dd (possibly growing
slightly larger) and five arms of about 15 mm in length. The dorsal disk is covered with
low granules, obscuring the disk scales. The radial shields are almost round, about a
fifth as long as the dd, and covered with granules. Of the five lateral mouth papillae, the
8

proximal three are lamella-like, extending deep into the mouth slit. The most proximal
lamellar papilla is positioned on the dental plate, the other two on the oral plate. The
two distalmost papillae are oval and flat, arising from the adoral shield. The
madreporite bears a hydropore at a lateral edge. Up to five conical arm spines are
present, all erect and as long as an arm joint. Each tentacle pore bears a single large
oval scale.
Etymology. The species name is a newly coined word based on the acronym for the
type locality EPR (East Pacific Rise). EPR is here regarded as feminine.
Description of holotype. The disk measures 3.7 mm in diameter. All five arms are
broken, but at least four times longer than dd. The dorsal disk is covered by small,
round, imbricating scales and larger, almost round, radial shields, all of which are
obscured by low, slightly rough granules (partly abraded; Fig. 6A, B). The disk is
slightly incised interradially. The pairs of radial shields are each separate along their
distal half. The arms are not particularly noded; there are five erect arm spines on the
proximal segments, tapered, smooth, and about as long as an arm joint. The dorsal
arm plate is fan-shaped, plates on neighbouring joints just touching. On the distal part
of the arm, the dorsal plates are widely separated by the large lateral plates, and the
three short arm spines bear thorny ridges along their length. The arm spine articulation
is formed by two parallel ridges (Fig. 6C).
The ventral disk is formed of numerous small, round, overlapping scales bearing
scattered granules similar to those of the dorsal side. The first ventral arm plate is
smaller than the others, located almost completely inside the mouth slit (Fig. 6D). The
other ventral arm plates are pentagonal with an obtuse proximal angle, concave lateral
edges, and slightly concave distal edge. Neighbouring plates are separate. Each
tentacle pore is covered by a large, oval to leaf-shaped scale. The adoral shields have
curved, concave proximal edges and extend around the lateral angle of the oral shield,
separating it from the lateral arm plates. The oral shield is wider than long with an
obtuse proximal angle and a convex distal edge bearing one to several granules similar
to the disk granules. The madreporite bears a large hydropore at a lateral edge (left in
oral view). The dental plate bears conical pointed teeth on its proximal surface and a
lateral, blade-like papilla on either side, all of which almost meet (Fig. 6E). On three
jaws a small papilla is present on the ventral edge of the dental plate, between the
lateral blades. Each oral plate bears two similar blade-like lateral papillae, all of which
extend almost vertically into the mouth slit (Fig. 6F). The edge of the adoral shield next
to the second tentacle pore bears two scale-like papillae, which continue the row of
mouth papillae (Fig. 6E).
The coloration of this species in life is a light pinkish orange to cream.
Paratype variation. Oral plates were dissected from a smaller paratype to save the
holotype. The oral plate is of an elongated axe-shape with small muscle attachment
scars (Figs 6 G, H).
Most of the collected specimens are rather small juveniles, the holotype being the
largest adult. The largest paratype measures 3.5 mm dd. Its hydropore is more on top
of the madreporite than in the holotype. The next smaller paratype, at 3.1 mm dd, has
no visible hydropore at all, while smaller individuals have visible hydropores. The disk
granules are abraded to varying extents, leaving parts of the disk naked. The number
of granules on the edge of the oral shields varies both between jaws and between
individuals. Apart from this, variation is related ontogenetic stage, as described below.
The animals are often covered with bright orange-red mineral particles, which are also
found in their mouth and stomach (Fig. 5D, E).
Postmetamorphic development (paratypes). The smallest postlarva found measures
0.7 mm dd; its arms have three joints and a tapered terminal plate (Fig. 7A). The dorsal
disk is formed by the central primary plates and six instead of the usual five radial
primary plates, which is probably an aberration. A few conical granules are scattered
9

across the disk. The plate structure is multilayered with larger fenestrations in the
centre of the plates and a rough surface. The radial shields have just begun to form
distal to the radial primary plates. Each lateral arm plate bears two pointed, thorny
spines and the proximal segment bears a small, triangular dorsal plate. The jaw bears
a large, pointed tooth on the small dental plate and a wide buccal scale (= first mouth
papilla) on the oral plate (Fig. 7B). The adoral shield bears a short conical spine. The
oral shields are visible at the disk edge, the madreporite having a projecting hydropore
(not figured).
At 0.8 mm dd the first interradial plates are present (Fig. 7C). This individual has only
five primary radial plates, confirming the above assumption that six plates is not the
typical pattern. The dental plate bears a wide tooth and a short secondary papilla to
either side (Fig. 7D). The adoral shield spine is flattened and points across the second
tentacle pore. The oral shields are drop-shaped. The madreporite bears a conical
protrusion with a large hydropore opening. Ventral arm plates are present on three
joints, about twice as long as wide, with concave lateral edges, a narrow proximal
angle, and wider, convex distal edge.
At 1.0 mm dd there are two interradial plates, a proximal and a distal one of equal size,
but it is unclear which of them formed first (Fig. 7E). The fan-shaped dorsal arm plates
are widely separated by the long lateral plates. The still projecting hydropore is slightly
off-centre on the madreporite; the mouth papilla on the dental plate has become wider
and slanting, with its distal end deeper than its proximal end (Fig. 7F). The buccal scale
is unchanged. A large, flat adoral shield spine covers the second tentacle pore (on one
plate there are two spines). A large, oval, flat scale covers each tentacle pore on the
arm.
At 1.2 mm dd the rounded wedge-shaped k-plate has formed between the proximal
ends of the radial shields and the number of granules on the disk has increased (Fig.
7G). Of the first dorsal arm plate, only the distal edge is visible beneath the radial
shields. A row of three round scales forms the ventral disk (Fig. 7H). The second
tentacle pore has moved closer to the mouth slit. The number of mouth papillae is
unchanged. The bursal slits have formed.
At 1.4 mm dd additional interradial plates have formed and the number of granules has
increased (Fig. 8A). Each lateral arm plate bears three equal spines. On some jaw
edges a third mouth papilla has formed on the proximal part of the oral plate, between
the second papilla and the buccal scale (Fig. 8B). On other jaw edges, the buccal scale
is still as wide as the entire oral plate, which suggests that the third papilla forms by
division of the buccal scale. Both proximal papillae are beginning to attain the blade-
like shape and orientation of the adult (Fig. 8C). The adoral shield bears two flat, oval
scales, the proximal one being smaller than the distal one, which suggests that the
proximal one has formed secondarily and that the distal scale is the adoral shield
spine. The hydropore is now almost on the same level as the plate surface, moved to
the lateral part of the madreporite.
At 1.6 mm dd numerous additional scales have formed on the dorsal disk (Fig. 8D).
The three mouth papillae have attained their blade-like shape and the scales on the
adoral shield form a row continuous with them (Fig. 8E). The oral shields are about as
wide as long.
At 2.0 mm dd each lateral arm plate bears four equal, tapered spines (Fig. 8G). The
disk granules are thorny and higher than wide (Fig. 8H). The oral shields have become
wider than long (Fig. 8I).
At 2.3 mm dd the animals can be identified using adult characteristics (Fig. 8J, K). The
hydropore has not yet reached its final position at the edge of the madreporite, but the
proximal three mouth papillae have a pronounced blade-like shape and a vertical
orientation.
10

Comparisons. The Ophiacanthidae include a wide variety of genera and species,
many of which are ill-defined and in great need of revision (O’Hara and Stöhr in press).
The current diagnosis of the family includes a wide range of character states, such as a
disk covered more or less with spinelets, granules, or rods of varying size and shape,
more or less noded arms, and thorny or smooth arm spines (Paterson 1985). With
such a wide definition, it is difficult to decide whether a species belongs in this family or
not. The granulated disk, the position of the second tentacle pore inside the mouth slit,
the interradially incised disk, and the large tentacle scale of the new species fit within
the definition of the Ophiacanthidae. Various skeletal elements have been suggested
as characteristic of certain taxa, but few have been confirmed to have family-specific
taxonomic value. Paterson (1985) suggested that a comma-shaped arm spine
articulation might be specific for most Ophiacanthidae, excepting his subfamily
Ophiohelinae, which includes species with a sac-like disk that probably lacks radial
shields. Recently, several species of Ophiacanthidae not belonging to the
Ophiohelinae have been shown also to lack a comma-shaped articulation (Stöhr and
Segonzac 2005; O’Hara and Stöhr in press), which brings into question the taxonomic
value of this character. Murakami (1963) described the oral plates of a large number of
species from most families of ophiuroids and showed them to be family-specific.
According to that work, the oblong axe-like shape of the oral plate with rather small
adradial and abradial muscle attachment scars places Ophiolamina eprae within the
Ophiacanthidae.
The present new species shows affinities with several of the subfamilies of
Ophiacanthidae proposed by Paterson (1985). The elongate adoral shields are similar
to those of the Ophiotominae and the flat, round distal mouth papillae resemble those
of the ophiotomine Ophiolimna Verrill, 1899, but the jaw is not elongate and the second
tentacle pore is not superficial as is typical for that subfamily (Paterson 1985). The
short, round radial shields, the disk granules, and the shape and structure of the arms
resemble those of Ophiomitrella in the subfamily Ophioplinthacinae, but that genus has
short adoral shields. Among the Ophioplinthacinae, some species of Ophiocamax
Lyman, 1878 possess long adoral shields (Paterson 1985) but are otherwise different
from the new species, which nonetheless may perhaps belong to this subfamily. The
delimitation of the ophiacanthid subfamilies needs further examination, as is
exemplified by the recent removal of Ophiomelina Koehler, 1922 from the
Ophioplinthacinae by its synonymisation with Ophiacantha Müller and Troschel, 1842,
which belongs to the subfamily Ophiacanthacinae (O’Hara and Stöhr in press). While
O. eprae clearly belongs within the Ophiacanthidae, placing it within a subfamily would
only add to the existing confusion.
The blade-like proximal mouth papillae are unique for this species among all ophiuroids
and bear some similarity to the mouth papillae of Ophioctenella acies, because they
may superficially be mistaken for a single wide papilla along the jaw edge when viewed
from the oral side.
Habitat and distribution. Ophiolamina epraewas collected at 13°N (Grandbonum
site), in the hydrothermal sediment on the walls of a sulphide edifice colonized by some
siboglinid tubeworms Riftia pachyptila and galatheid crabs Munidopsis subsquamosa,
and at the Julie site, around a hydrothermal fluid emission (T° = 13 to 18°C) with some
R. pachyptila and mussels and associated bythograeid crabs and hippolytid shrimps.
The ophiuroids were preferentially associated with the mussels, but some were
collected with empty tubes of R. pachyptila.
Discussion
Four species of ophiuroid are now known from chemosynthetically based
environments, two each of the families Ophiuridae and Ophiacanthidae. Among the
previously described species, Ophienigma spinilimbatum is restricted to seeps, while
11

Ophioctenella acies occurs at both vents and seeps and has a wide distribution across
the Atlantic Ocean (Stöhr and Segonzac 2005). Both new species appear to be
restricted to vents. So far, none of these species has been found in more than one
ocean.
The geographic distribution of the ophiacanthid Ophiolamina eprae as known at
present is discontinuous, with a large gap between the type locality at 12°48’N and its
southern area of occurrence. Its population densities in samples are much lower than
those of the ophiurid Spinophiura jolliveti, except at Animal Farm (SEPR, 18°36’S), but
this may also reflect poor collecting results. Ophiacanthidae are generally known to
have a cryptic life-style, hiding in crevices and often epizoic on coral and other animals,
which may make them more difficult to collect. The largest numbers of individuals of
Ophiolamina eprae (small juveniles) were collected by the quantitative pot method
employed by the SEPR cruise in 1999 at Animal Farm. Both ophiuroid species have
been collected from mussel beds and aggregations of tubeworms, two phylogenetically
widely separate taxa. The ophiuroids may find shelter among the shells and tubes and
perhaps feed on bacterial mats or waste products generated by both mussels and
worms. Ophiolamina eprae seems attracted to decaying organic material, since its
greatest numbers were found at the Animal Farm vent field, in a dying mussel
community with no hydrothermal activity (Van Dover, pers. comm.). Densities of both
species were far lower than those of Ophioctenella acies of MAR vents, which reaches
densities up to 80 ind. dm-2 at some sites (Gebruk et al. 2000), but perhaps the most
favourable sites for the two new species have not been found yet. At Animal Farm
(18°36' S), Spinophiura jolliveti was collected in 1999 (SEPR cruise) and 2004
(BIOSPEEDO), and at the Oasis-Rehu site, in 1993 (NAUDUR), 1999 (SEPR), and
2004 (BIOSPEEDO), which indicates a certain temporal stability of the environmental
conditions favourable to this species. The two new species occur in sympatry at some
sites (Animal Farm, Rehu), but not enough is known about their adaptations and life-
style to understand the ecological relationships between the species.
The presence of juveniles of different age classes suggests several previous
recruitment events, instead of occasional random settling. This is a strong indication
that both species are adapted to the vent environment. Spinophiura jolliveti settles at
an early postmetamorphic stage with arms consisting of only the terminal plate, and at
0.4 mm disk diameter it is one of the smallest bottom-living stages known (Sumida et
al. 1998; Stöhr 2005). The larger postlarva of Ophiolamina eprae may suggest later
settlement or abbreviated development, although the smallest stage may not have
been found yet.
Nothing is known about the function of the mouth papillae in ophiuroids. The great
diversity in their shape, size, and number suggests that they are not just for closing the
mouth gap, but somehow assist in feeding. The blade-like proximal papillae of
Ophiolamina eprae may perhaps function as scrapers of bacterial mats or for grinding
up dead tissue if the species is a scavenger.
Acknowledgements
The authors thank the chief scientists (see Table 1) and crews of R/V L’Atalante Nadir,
Vickers, and Natsushima, of D/S Nautile, Alvin, Shinkai 200 and ROV Victor 6000, for
collecting all the specimens studied here, and most particularly Didier Jollivet, CNRS,
Roscoff (BIOSPEEDO) and Nadine Le Bris, Ifremer, Brest (PHARE). The BIOSPEEDO
and PHARE cruises were funded by CNRS and Ifremer, on the framework of the two
thematic workshops DORSALES and Ecchis GDR. We thank N. Le Bris and P. Briand
(Ifremer, Brest) for supplying the colour photos. We also thank B. Govenar
12

(Pennsylvania State University, USA), R. Vrijenhoek (MBARI, California), and C. Van
Dover (College of William and Mary, USA), for donating their samples. Many thanks
also to C. Van Dover and two anonymous referees for valuable suggestions to improve
the manuscript. The Alvin/Atlantis programs were funded by grants from the U.S.
National Science Foundation to R. C. Vrijenhoek (OCE-0241613) and to C. L. Van
Dover (OCE-0350554). This study was supported by a grant from Riksmusei Vänner,
Stockholm, to S. Stöhr.
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Tables
Table 1. Cruises to the Pacific Ocean during which the ophiuroids described in this
paper were collected. SEPR, South East Pacific Rise.
Cruise Chief Scientist Ships/ROVs Region Date
KAIKO-
NANKAI X. Le Pichon,
ENS, Paris NO Nadir/DSV
Nautile Nankai Trough,
S of Tokyo 13/08-
09/09/1989
HERO 91 D.
Desbruyères,
Ifremer, Brest
NO Nadir and RV
Vickers EPR, 13°N,
9°50’N 30/09-
04/11/1991
PITO J.
Francheteau,
UBO, Brest
NO Nadir/DSV
Nautile Easter
Microplate 11/1993
NAUDUR J.-M. Auzende,
IRD, New
Caledonia
NO Nadir/DSV
Nautile EPR, N Easter
Island 03-
30/12/1993
NAUTIMATE B. Mercier de
Lépinay and F.
Michaud,
Université
Nice, France
NO Nadir/DSV
Nautile off Mexico 16/01-
09/02/1994
HOT 96 F. Gaill,
Université
Paris VI
NO Nadir/DSV
Nautile EPR, 13°N, 9°N 09/02-
23/03/1996
BIOACCESS
98 J. Hashimoto,
JAMSTEC,
Japan
NO
Natsushima/DSV
Shinkai 2000
SW Pacific,
Manus Basin, N
of Papua New
Guinea
13-
25/11/1998
SEPR C. L. Van DSV Alvin SEPR, 17°S 02/02-
14

Dover,
Williamsburg,
U.S.A.
23/02/1999
HOPE 99 F. Lallier,
Roscoff,
France
NO Atalante/DSV
Nautile EPR, 13°N, 9°N 09/04-
25/05/1999
PHARE N. Le Bris,
Ifremer, Brest NO Atalante/ROV
Victor 6000 EPR, 13°N 30/04-
03/06/2002
FIELD J. Voight,
Penn State
University
DSV Alvin EPR, 9°N 10-
12/11/2003
BIOSPEEDO D. Jollivet,
CNRS,
Roscoff
NO Atalante/DSV
Nautile EPR, 07-21°S 31/03-
13/05/2004
PAR 5 R. Vrijenhoek,
MBARI,
California
RV Atlantis/DVS
Alvin PAR, 23°-38°S 12/03-
06/04/2005
15

Table 2. Collecting sites of ophiuroids at hydrothermal vents and cold seeps in the
Pacific Ocean. Dive numbers are preceded by cruise or vessel name. Abbreviations: A,
Alvin; BA, BIOACCESS 98; BAB, Back Arc Basin; BS, BIOSPEEDO; Env,
environment; EPR, East Pacific Rise, HE, HERO91; HO, HOPE 99; HT, HOT 96; KN,
KAIKO-NANKAI; N, number of specimens; ND, NAUDUR; NM, NAUTIMATE; P, PAR
5; PH, PHARE; PI, PITO; SEPR, South EPR; V, vent, CS, cold-seep.
Site Dive Equipm
ent Latitude Longitude Dept
h
(m)
Species N En
v
Nankai
Trough KN05 Box
core 33°49.80
’N 137°55.20
’E 199
9 Ophiomitre
lla sp. 1 CS
Nankai
Trough KN06 Box
core 33°50.00
’N 137°49.70
’E 215
3 Ophiomitre
lla sp. 2 CS
Nankai
Trough KN09 Box
core 33°47.80
’N 137°49.70
’E 209
5 Ophiomusi
um sp. 1 CS
Nankai
Trough KN14 Box
core 33°49.40
’N 137°55.20
’E 206
0 Ophiomusi
um sp.,
Ophiomitre
lla sp.
1,
1 CS
EPR, 9N,
East Wall HE09 Basket 1 09°50.99
’N 104°17.59
’W 249
1 Spinophiur
a jolliveti 1 V
EPR, 9N HE61
4 Basket 09°40.30
’N 104°17.50
’W 252
0 Spinophiur
a jolliveti 1 V
Easter
Microplaq
ue,
Terevaka
Fault
PI19-
15 24°17.35
’S 115°37.35
’W 183
0 Ophiacant
ha richeri? 1 CS
?
SEPR,
Rehu ND06-
2 17°24.85
’S 113°12.15
’W 258
0 Spinophiur
a jolliveti,
Ophiacant
ha sp.
14,
1 V
SEPR,
Animal
Farm
ND12 18°36.50
’S 113°23.98
’W 267
3 Spinophiur
a jolliveti 1 V
Off
Mexico NM10-
4 Basket 18°22.00
’N 104°22.98
’W 325
9 Ophiura
sp. 23 CS
EPR 9N,
Biovent HT107
3 Basket 2 09°50.78
’N 104°17.61
’W 253
2 Spinophiur
a jolliveti 2 V
EPR 9N,
Biovent HT107
8 Basket 1 09°50.78
’N 104°17.61
’W 253
2 Spinophiur
a jolliveti
postlarvae
2 V
EPR,
13N,
Parigo
HT109
0 Basket 1 12°48.25
’N 103°56.34
’W 264
8 Spinophiur
a jolliveti 1 V
BAB
Pacmanu
s, Field E
BA107
5 03°43.65
’S 151°40.41
’E
169
4
Amphiura
sp. 1
SEPR,
Animal
Farm
A3343
,
A3349
Samples
1, 2, 4, 5 18°36.43
’S 113°23.96
’W 267
5 Ophiolami
na eprae,
Spinophiur
16,
3 V
16

a jolliveti
SEPR,
Oasis A3358 Sample
B-6 17°25.40
’S 113°12.32
’W 258
2 Spinophiur
a jolliveti 1 V
EPR, 9N,
East Wall A3489 Pots 2,
4, 5 09°50.53
’N 104°17.52
’W 249
1 Spinophiur
a jolliveti 6 V
EPR, 9N,
Biovent A3490 Grey
box, Pot
6
09°50.99
’N 104°17.59
’W 249
1 Spinophiur
a jolliveti 3 V
EPR, 9N,
East Wall A3727 Pots 2,
4 09°50.99
’N 104°17.59
’W 249
1 Ophiura
sp.,
Ophiolami
na eprae
1,
1 V
EPR, 9N,
Train
Station
A3728 Biobox 2 09°49.64
’N 104°17.37
’W 249
5 Ophiura
sp. 1 V
EPR, 9N,
Mussel
Bed
A3740 Pot 1 09°50.57
’N 104°17.49
’W 249
1 Spinophiur
a jolliveti 1 V
EPR 9N,
Biovent HO13
72 Slurp
gun 1 09°50.52
’N 104°17.62
’W 251
8 Spinophiur
a jolliveti 4 V
EPR 9N,
Biovent HO13
72 Slurp
gun 2 09°50.44
’N 104°17.65
’W 251
8 Spinophiur
a jolliveti 1 V
EPR 9N;
Biovent HO13
75 Basket 4 09°50.50
’N 104°17.54
’W 251
6 Spinophiur
a jolliveti 3 V
EPR 9N,
Mussel
Bed
HO13
77 Basket 09°50.37
’N 104°17.48
’W 251
2 Spinophiur
a jolliveti 1 V
EPR 13N,
Genesis HO13
86 Basket 4 12°47.72
’N 103°55.91
’W 263
2 Spinophiur
a jolliveti 5 V
EPR,
13N,
PP52
PH15
5 Slurp
gun 2 12°48.69
’N 103°56.36
’W 259
2 Ophiolami
na eprae 6 V
EPR,
13N, PP-
Ph08
PH16
4 Slurp
gun 4 12°49.01
’N 103°56.58
’W 262
2 Spinophiur
a jolliveti 1 V
EPR,
13N, PP-
Ph08
PH16
7 Basket 12°49.08
’N 103°56.56
’W 262
1 Spinophiur
a jolliveti 1 V
EPR, 9N,
Tica A3929
,
A3931
Artificial
substrat
e
09°50.45
’N 104°17.49
’W 250
0 Spinophiur
a jolliveti 6 V
SEPR,
White
Christmas
BS157
1 Slurp
gun 1 07°23.16
’S 107°47.06
’W 273
5 Ophiura
sp. 2 V
SEPR,
Oasis BS157
9 Basket 1 17°25.38
’S 113°12.29
’W 258
6 Ophiolami
na eprae 1 V
SEPR,
Oasis BS158
3 Basket 17°25.39
’S 113°12.28
’W 258
5 Spinophiur
a jolliveti 15 V
SEPR,
Animal
Farm
BS158
5 Basket 1 18°36.52
’S 113°23.99
’W 258
5 Spinophiur
a jolliveti,
Ophiolami
na eprae
13
2,
5
V
17

SEPR,
Wormwoo
d
BS158
7 Basket 17°34.91
’S 113°14.67
’W 259
6 Spinophiur
a jolliveti 1 V
SEPR,
Rehu BS159
0 Basket,
Alvinette 17°24.98
’S 113°12.14
’W 258
3 Spinophiur
a jolliveti,
Ophiolami
na eprae
51,
2 V
SEPR-
PAR #4091 Scoop 37°40.35
’S 110°52.68
’W 223
2 Spinophiur
a jolliveti 13 V
Figures
18

Fig. 1. Hydrothermal vent sites on the East Pacific Rise and Pacific-Antarctic Ridge.
Full circles mark the vent sites where one or both of the new species of ophiuroids,
Spinophiura jolliveti and Ophiolamina eprae, were collected. See Table 2 for details.
Fig. 2. Holotype (Muséum National d’Histoire Naturelle EcOs 22635) of Spinophiura
jolliveti gen. et sp. nov. (A) dorsal aspect; (B) ventral aspect; (C) close-up of dorsal
disk, showing radial shields and arm combs , (D) close-up of ventral disk, showing
small oral shield and genital papillae. Abbreviations: AC, arm comb; AS, adoral shield;
DAP, dorsal arm plate; GP, genital papillae; M, madreporite; MP, mouth papillae; OS,
oral shield; RS, radial shield; T, tooth; TPo, tentacle pore; TS, tentacle scale; VAP,
ventral arm plate. Scale bars in millimetres.
19

Fig. 3. Growth series of Spinophiura jolliveti gen. et sp. nov., SEM images, paratypes.
(A-C) postlarva of 0.4 mm dd, Swedish Museum of Natural History SMNH-Type-6062:
(A) dorsal aspect; (B) ventral aspect, demonstrating the absence of tooth and buccal
scale; (C) terminal plate. (D, E) Postlarva of 0.8 mm disk diameter (dd), SMNH-Type-
6076: (D) dorsal aspect; (E) ventral aspect. (F, G) Postlarva of 1 mm dd, SMNH-Type-
6058: (F) dorsal aspect; (G) ventral aspect. (H, I) Postlarva of 1.3 mm dd, SMNH-Type-
6058: (H) dorsal aspect; (I) ventral aspect. Abbreviations as in Fig. 1, plus: ASS, adoral
shield spine; CP, central primary plate; DP, dental plate; IR, interradial plate; OP, oral
plate; RPP, radial primary plate; SIR, secondary interradial plate. Scale bars in
millimetres. Type catalogue numbers refer to SEM stubs, not individuals.
20

Fig. 4. Continued growth series of Spinophiura jolliveti gen. et sp. nov., SEM images,
paratypes. (A) postlarva of 1.8 mm dd, Swedish Museum of Natural History SMNH-
Type-6056, dorsal aspect. (B,C) postlarva of 2.1 mm dd, SMNH-Type-6055, 6053: (B)
dorsal aspect; (C) ventral aspect. (D) individual of 3.1 mm dd, SMNH-Type-6061,
ventral aspect. (E, F) Individual of 5 mm dd, SMNH-Type-6064, 6065: (E) ventral
aspect; (F) dorsal aspect. Abbreviations as in Figs 1, 2, plus: k, k-plate. Scale bars in
millimetres. Type catalogue numbers refer to SEM stubs, not individuals.
21

Fig. 5. (A-C) Spinophiura jolliveti gen. et sp. nov.: (A) among mussels Bathymodiolus
thermophilus Kenk and Wilson, 1985, at EPR-13°N, PP-Ph08 hydrothermal vent site;
(B) same site, giant tube worms Riftia pachyptila Jones, 1981 with S. jolliveti (arrow);
(C) close-up detail of (B), showing S. jolliveti on dead Riftia. Photos from the dive’s
documentation video (Ifremer/PHARE/N. Le Bris). (D, E) Ophiolamina eprae gen. et sp.
nov., live specimen, paratype Muséum National d’Histoire Naturelle EcOh 20019,
about 3.5 mm disk diameter: (D) dorsal aspect; (E) ventral aspect, note the orange-red
particles adhering to the animal. Photos by Ifremer/PHARE/P. Briand.
22

Fig. 6. Ophiolamina eprae gen. et sp. nov., SEM images, (A, B, D-F) holotype,
Muséum National d’Histoire Naturelle (MNHN) EcOs 22637: (C, G, H) paratype, MNHN
EcOs 22639, 22640. (A) dorsal aspect; (B) disk granules; (C) lateral arm plate,
showing the spine articulation ridges; (D) ventral arm; (E) mouth, featuring the
madreporite with lateral hydropore; (F) mouth papillae viewed laterally; (G, H) oral plate
in adradial and abradial aspect, respectively. Abbreviations as in Fig. 1, plus: AR,
articulation ridge; LMP, lamellar mouth papillae. Scale bars in millimetres.
23

Fig. 7. Growth series of Ophiolamina eprae gen. et sp. nov., SEM images, paratypes.
(A, B) postlarva of 0.7 mm dd, Swedish Museum of Natural History SMNH-Type 6111:
(A) dorsal aspect; (B) ventral aspect, with glue residue obscuring the plates. (C, D)
postlarva of 0.8 mm dd, SMNH-Type- 6110: (C) dorsal aspect; (D) mouth. (E, F)
postlarva of 1.0 mm dd, SMNH-Type-6108: (E) dorsal aspect; (F) ventral aspect. (G, H)
postlarva of 1.2 mm dd, SMNH-Type-6111: (G) dorsal aspect; (H) ventral aspect.
Abbreviations as in Figs 1-3, plus: BS, buccal scale; LAP, lateral arm plate; Scale bars
in millimetres. Type catalogue numbers refer to SEM stubs, not individuals.
24

Fig. 8. Continued growth series of Ophiolamina eprae gen. et sp. nov., SEM images,
paratypes. (A-C) postlarva of 1.4 mm dd, Swedish Museum of Natural History SMNH-
Type-6108: (A) dorsal aspect; (B) ventral aspect; (C) mouth papillae. (D, E) postlarva
of 1.6 mm dd, SMNH-Type-6108: (D) dorsal aspect ; (E) ventral aspect. (F-H) postlarva
of 2.0 mm dd, Muséum National d’Histoire Naturelle EcOs 22638: (F) dorsal aspect;
(G) disk granules; (H) ventral aspect. (I, J) individual of 2.3 mm dd, SMNH-Type-6109:
(I) ventral aspect; (J) dorsal aspect. Abbreviations as in Figs 1-4. Scale bars in
millimetres. Type catalogue numbers refer to SEM stubs, not individuals.
25