Crustacea: Ostracoda: Cylindroleberididae - BioOne

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 120(3):271–278. 2007.

A new species of the genus Diasterope Kornicker, 1975 (Crustacea: Ostracoda: Cylindroleberididae) from Culebra Island, Puerto Rico Andre´s G. Morales-Nuń˜ez and Louis S. Kornicker* (AM-N) Department of Marine Sciences, University of Puerto Rico Mayagu ¨ ez Campus, Puerto Rico, 00680, e-mail: [email protected] (LSK) Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, MRC 163, Washington, D.C. 20013-7012, U.S.A., e-mail: [email protected]

Abstract.—The present work is the first published report of a benthic member of the Myodocopida off Puerto Rico. The collection contained a single specimen of an interesting new species, Diasterope puertoricensis (family Cylindroleberididae), which is described herein.

Culebra Island is located off the east coast of Puerto Rico (Fig. 1). The senior author participated in a broad study of the fauna off the western coast of the island (Morales-Nuń˜ez 2005). Benthic Ostracoda in the subclass Myodocopa that were collected in core samples are to be described by the senior author in a later paper. The collection contained a single specimen of an interesting new species of Diasterope (family Cylindroleberididae), which is described herein. Previous studies of benthic marine ostracodes of Puerto Rico include those of Brady (1880:13), who reported seven species of ostracodes in the subclass Podocopa from 390 fathoms off Culebra Island; Baker (unpublished Master’s thesis 1965), who reported 12 species of Myodocopa and many species of Podocopa from off Puerto Rico; and Baker & Hulings (1966:108), who reported the distribution of Podocopa around Puerto Rico, based partly on the Baker thesis of 1965. The myodocopids reported by Baker (1965) do not include the genus described herein, and none were from the vicinity of Culebra. The present work is

* Corresponding author.

the first published report of a benthic myodocopid off Puerto Rico. Materials and Methods The samples were taken on alternate months by divers at a mean depth of 28 m, from October 2002 to October 2003, in an area about 120 m wide and 100 m long; samples were taken with a PVC core sampler (8.8 cm diameter, 10 cm length, 62 cm2 area). Field samples were filtered through a stainless-steel sieve of 0.5 mm mesh size, preserved in 4% formalin-seawater solution with Rose Bengal stain, and preserved in 70% ethanol. Systematics Subclass Myodocopa Sars, 1866 Order Myodocopida Sars, 1866 Suborder Myodocopina Sars, 1866 Family Cylindroleberididae Mu ¨ ller, 1906 Subfamily Cylindroleberidinae Mu ¨ ller, 1906 Genus Diasterope Kornicker, 1975 Type species.—Diasterope pilosa Poulsen, 1965 (designated by Kornicker 1975) Composition.—This genus contains ten named species, including a new species

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Fig. 1.

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON

Location of collecting area off Culebra Island.

described herein: D. bisetosa Poulsen, 1965; D. canina Poulsen, 1965; D. grisea (Brady, 1898); D. perseyiensis Chavtur, 1983; D. pilosa Poulsen, 1965; D. schmitti Kornicker, 1975; D. tenuiseta Poulsen, 1965; D. procax Kornicker & Iliffe, 2000; D. wirraka Syme & Poore, 2006; and the new species described herein. Two species, D. tenuiseta and D. canina, were collected in the Virgin Islands, West Indies, not far from the locality of the new species. Distribution.—The genus is widespread, from about 49uN in the Strait of Georgia, Canada, to the Ross Sea, Antarctica, with known depth range of 11–400 m (Kornicker 1975:389). Diasterope puertoricensis, new species Figs. 2–4 Etymology.—The species is named in honor of the country where the holotype was collected. Holotype.—USNM 1102439, late juvenile male (probably A-1), appendages on slide, carapace in alcohol (unique specimen). Paratypes.—None. Type locality.—3.2 km Southwest of Culebra Island, Puerto Rico (18u169N, 65u199W). Distribution.—Southwest of Culebra Island at depth of 28 m. Description.—Juvenile male, probably A-1 (Figs. 2–4).

Carapace (Fig. 2): Elongate with oblique posterodorsal margin and smooth surface on carapace. Anterior margin rounded with incisure ventral to valve midheight. Infold (Fig. 2B, C): (Condition of valves did not permit accurate description of bristles of infold). Anterior infold with indistinct bristles (Fig. 2B). Posterodorsal infold (Fig. 3C): broad with 4 processes between list and posterior shell edge; list with short flap-like bristles and a few indistinct bristles between adjacent flaplike bristles. Carapace Size: Carapace length 1.68 mm, height 0.68 mm. First antenna (Fig. 2D): First article bare. Second article with 1 dorsal spinous bristle (broken on illustrated limb) and 1 bare lateral bristle. Third article with 6 dorsal bristles (most spines on bristles not shown): 2 single with long spines, 1 pair with long spines, and 1 pair with spines (medial with short spines, lateral with long spines); ventral margin with 1 small bristle that appears to be on second article. Fourth article with 1 dorsal bristle with short spines (spines not shown) and 2 bare ventral bristles. Oblique suture between third and fourth articles not well developed on lateral side. Fifth article with sensory bristle with small filament proximal to 6 long distal filaments. Sixth article with 1 long medial bristle. Seventh

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Fig. 2. Diasterope puertoricensis, holotype. A, complete specimen, lateral view, length 1.68 mm; B, anterior right valve, inside view; C, posterior right valve, inside view; D, right first antenna, lateral view; E, lateral eye, lateral view.

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Fig. 3. Diasterope puertoricensis, holotype. A, left second antenna, lateral view; B, proximal part coax endite right mandible, medial view; C, basis left mandible, medial view; D, part right mandible, lateral view; E, part left mandible, lateral view.


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Fig. 4. Diasterope puertoricensis, holotype. A, part right maxilla, medial view; B, part left fifth limb, lateral view; C, comb right fifth limb, lateral view; D, right sixth limb, lateral view; E, seventh limb; F, posterior of body and right lamella of furca; G, Organ of Bellonci; H, distal end of gill.

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and eighth article fused (not all filaments and spines shown on bristles). Seventh article: a-claw shorter than bristle of sixth article; b-bristle about twice length of aclaw, with 5 marginal filaments; c-bristle 2.5 times length of a-claw, with 11 filaments. Eighth article: d-bristle minute; e-bristle about 1.5 length of a-claw, bare with blunt tip; f-bristle about twice length of a-claw, with 5 filaments; g-bristle about 3 times length of a-claw, with 7 filaments. All filaments and spines on bristles not shown in Fig. 2D. Second antenna (Fig. 3A): Protopod broad, ham-shaped; margins and surfaces without spines but with short distal medial bristle (not shown). Endopod with 3 articles: first article bare; second article with short dorsal lateral bristle; third article with 1 long bare proximal bristle. Exopod: first article elongate and bare; triangular basal spines present on third to eighth articles; basal spine of eighth article and lateral spine on ninth article about half length of ninth article; bristle of second article with ventral spines; third to eighth articles with natatory bristles, some bristles with slender proximal ventral spines; ninth article with 4 bristles (2 long bristles with only natatory bristles; 2 shorter bristles bare). Mandible (Fig. 3B–E): Coxal endite partly fragmented; small bristle near base of ventral branch; ventral branch with 3 small spines at tip (Fig. 3B). Basis endite with 4 spinous terminal bristles, 3 triaenid bristles (1 broken) with 5–6 pairs of spines, 2 short dwarf-bristles and one thumb-like peg (Fig. 3D); dorsal margin of basis with 1 short midbristle, 1 terminal dorsal process with 2 min terminal spines, and 1 long terminal bristle lateral to process (Fig. 3C, D). Exopod with 2 small terminal bristles and reaches middle of dorsal margin of first endopodial article (Fig. 3B, D). First endopodial article with 3 long spinous ventral bristles (2 shown) (Fig. 3D). Second endopodial article: dorsal margin with slender a-bristle,

stouter b-bristle, very stout c-bristle, and long slender spinous d-bristle; d-bristle more slender than b- and c-bristles (Fig. 3D, E); 1 small bristle proximal to a-bristle, 1 short medial and 1 long lateral bristle between b- and c-bristle, and 1 long lateral bristle between c- and d-bristle (Fig. 3D, E), and 1 long medial bristle distal to d-bristle, and 4 small medial bristles forming row near c-bristle (outer bristle with marginal spines; all bristles not shown); ventral margin with 3 long terminal bristles (Fig. 2D). End article with 1 claw with ventral spines and 6 bristles (not all shown). Maxilla (Fig. 4A): Epipod tapered, with few indistinct hairs at tip. Endite I with 4 bristles (3 long, spinous; and 1 short, bare); endite II with 3 long bristles. Basis: 2 lateral bristles near dorsal margin (1 proximal, 1 distal); ventral margin with 1 short proximal bristle and 1 long terminal bristle (not shown on illustrated limb). Endopod fragmented. Fifth limb (Fig. 4B, C): Epipod with 62 bristles. Tip of comb with long hairs; long exopodial bristle observed only on left limb (Fig. 4B); 2 pairs of short lateral bristles at midlength closer to ventral margin, and 3 short bristles (1 proximal and 2 distal) with bases almost on ventral margin; ventral margin with row of about 32 spinous bristles (Fig. 4C, spines not shown). Sixth limb (Fig. 4D): Anterior margin with 1 short bare bristle at upper endite and 1 short bare bristle at lower endite. Lateral anteroventral flap with marginal hairs. Anterior tip of skirt and flap with 4 spinous bristles. Anterior 0.67 of ventral margin of skirt without bristles; posterior 0.67 of ventral margin with row of 16 short, spinous bristles followed by 1 short, indistinct bristle; posteroventral corner without bristles (posteroventral corner observed on only 1 limb). Anterior, ventral and posterior margins of limb with hairs. Seventh limb (Fig. 4E): Proximal group with 5 bristles (3 on 1 side, 2 on other);


distal group with 6 bristles (3 on each side); each bristle tapered and with up to 5 bells; terminus consisting of opposing combs, each with about 10 spinous teeth. Furca (Fig. 4F): Each lamella with 6 claws followed by 2 bristle-like claws. Concave margins of claws 1–6 with 2 rows of small teeth and single larger tooth at regular intervals. Bellonci Organ (Fig. 4G): Elongate with suture at 0.33 length and rounded tip. Eyes: Medial eye with amber color. Lateral eye well developed, with about 16 ommatidia (Fig. 2E). Lateral eyes appearing red in reflected light, possibly resulting from addition of Rose Bengal to sample. Comparisons.—The new species Diasterope puertoricensis is very close to D. canina Poulsen, 1965, in that both species have a small thumb-like terminal process on the dorsal margin of the bases of the mandible. No other cylindroleberids have a similar thumb-like process. The main difference in the two species is that the dbristle on the dorsal margin of the first endopodial article of the mandible is thinner than the a- and b-bristles in D. puertoricensis. According to Poulsen (1962:361), the d-bristle is stouter than the a- and b-bristles in D. canina. The dbristle in D. canina is about the same length as the c-bristle (Poulsen 1962: Fig. 119e), whereas the d-bristle is much longer than the c-bristle in D. puertoricensis (Fig. 3E). Also, the thumb-like terminal process on the basis of the mandible of the Diasterope puertoricensis bears 2 terminal spines, which are absent on the process of D. canina. Additional differences between the two species are that the first antenna of the new species has a small ventral bristle on the third article, and the second article of the endopod of the second antenna bears a small bristle. Because only one specimen of each species is known, it was not possible to determine whether the differ-

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ences are the result of intraspecific variability. It is estimated that both specimens are A-1 males. Diasterope puertoricensis differs from the other, previously described species of the genus in having a thumb-like terminal process on the dorsal margin of the basis of the mandible. Some juvenile cylindroleberids have a short proximal filament on the sensory bristle of the first antenna that is absent on the adult. If an adult of D. puertoricensis is collected and it does not have the short proximal filament, the genus of the species will have to be reconsidered. Discussion of thumb-like terminal process on mandibular basis.—The dorsal margin of the basis of cylindroleberids usually bears 2 terminal bristles. Poulsen (1962:360) considered the thumb-like process on D. canina to be the result of the lateral one of the 2 bristles having a different form. The junior author (LK) agrees with that interpretation. The dorsal process on D. puertoricensis is also interpreted to be a modified lateral bristle. If either species had lacked an exopod, the thumb-like process could have been misidentified as an exopod. Many halocyprids bear either a bristle or a thumb-like process on the dorsal margin of the basis of the mandible, which has usually been interpreted as an exopod. The presence of both a thumb-like process that resembles an exopod and an exopod on D. canina and D. puertoricensis suggests that the process on mandibles of halocyprids may not always be an exopod. Acknowledgments The specimens were collected as part of a University of Puerto Rico project ‘‘Developing Production for Sustainable Offshore Cage Culture in Puerto Rican and Caribbean Waters,’’ and we thank participants for their help in collecting samples.

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The senior author thanks the Smithsonian Institution (Office of Research Training and Services), the Puerto Rico Sea Grant College Program, and the Alliance for Graduate Education and the Professoriate (AGEP) for providing financial support to work at the Smithsonian Museum of Natural History. The senior author especially thanks Elizabeth Harrison-Nelson, Smithsonian Institution (SI), for her help in processing papers prior to his visit and for her assistance during the stay at the Smithsonian Museum of Natural History, and for preparing the manuscript for publication. We are grateful to Molly K. Ryan (SI) for preparing Fig. 1. Appendages were drawn by the senior author. Literature Cited Baker, J. H. 1965. Recent marine ostracod assemblages of Puerto Rico. Unpublished M.S. thesis, Texas Christian University, Fort Worth, 86 pp. ———, & N. C. Hulings. 1966. Recent marine ostracod assemblages of Puerto Rico.—Institute of Marine Science (Texas) 11:108–125. Brady, G. S. 1880. Report of the Ostracoda dredged by the H.M.S. Challenger during the years 1873–1876.—Report on the Scientific Results of the Voyage of H.M.S. Challenger: Zoology, 1–184. ———. 1898. On new or imperfectly known species of Ostracoda, chiefly from New Zealand.— Transactions of the Royal Society of Edinburgh 35(2)14:489–525.

Chavtur, V. G. 1983. [New species of ostracods (Sarsiellidae) from the South of Vietnam.— Proceedings, Institute of Marine Biology, Far East Science Center of the USSR Academy of Sciences (Vladivostok)]: 849–849. [In Russian] Kornicker, L. S. 1975. Antarctic Ostracoda (Myodocopina). Parts 1 and 2.—Smithsonian Contributions to Zoology 163:1–389. ———, & T. M. Iliffe. 2000. Myodocopid Ostracoda from Exuma Sound, Bahamas, and from marine caves and blue holes in the Bahamas, Bermuda, and Mexico.—Smithsonian Contributions to Zoology 606:1–95. Morales-Nu ´ n˜ez, A. G. 2005. Temporal and spatial characterization of tropical benthic infauna around submerged cages for the culture of fish in the open sea. Unpublished M. S. thesis, University of Puerto Rico, Mayaguëz, 65 pp. [In Spanish.] Mu¨ller, G. W. 1906. Ostracoda. Die Ostracoden der Siboga-Expedition. In MaxWeber, ed., Siboga-Expeditie, Uitkomsten op Zoologisch, Botanisch, Oceanographisch en H. M. Siboga…, Monographien 30:1–40. E. J. Brill, Leiden. Poulsen, E. M. 1962. Ostracoda-Myodocopa, 1: Cypridiniformes-Cypridinidae.—Dana Report 57:1–414. ———. 1965. Ostracoda-Myodocopa, 2: Cypridiformes-Rutidermatidae, Sarsiellidae, and Asteropidae.—Dana Report 65:345–361. Sars, G. O. 1865 [1866]. Oversigt af Norges marine Ostracoder.—Forhandlinger i VidenskabsSelskabet i Christiania 8:1–130. Syme, A. E., & G. B. Poore. 2006. Three new ostracod species from coastal Australian waters (Crustacea: Ostracoda: Cylindroleberididae).—Zootaxa 1305:1–67. Associate Editor: Janet W. Reid