Ophiocoma (Breviturma) dentata Müller & Troschel, 1842

Stöhr, Sabine, Boissin, Emilie & Hoareau, Thierry B., 2013, Taxonomic revision and phylogeny of the Ophiocoma brevipes group (Echinodermata, Ophiuroidea), with description of a new subgenus (Breviturma) and a new species, European Journal of Taxonomy 68, pp. 1-26 : 13-17

Ophiocoma (Breviturma) dentata Müller & Troschel, 1842

Figs 2E, F , 4 F-J, 5B, E, H, K, N, Q

Ophiocoma dentata Müller & Troschel, 1842: 99 , pl. 7, figs 3-3a.

Ophiocoma ternispina v. Martens, 1870: 252.

Ophiocoma insularia Lyman, 1862: 80 .

Ophiocoma variegata Smith, 1876: 39 .

non Ophiocoma marmorata – Devaney 1970: 17.

Diagnosis

Species of Ophiocoma (Breviturma) subgen. nov. characterized by rarely possessing more than four arm spines and if present only at few segments; arm spines never annulated; variable in colour pattern (uniformly or marbled brown, reticulated of spotted); dorsal disc granule density less than 150 mm-2. Maximum size at least 28 mm dd ( Devaney 1970).

Type material examined

Holotype ZMB Ech 931 Holotype of Ophiocoma dentata .

COLLECTING DATA. Celebes (Sulawesi), 1° 50.875’ S 120° 31.675’ E (from atlas), collector Deppe.

MORPHOLOGICAL DATA. 18-19 mm dd (irregular disc), granules on dorsal disc mostly rubbed off, light and dark brown pattern on dorsal disc, dorsal arms medium brown, ventral interradii fully granulated, white, DAP W:L 2:1, arm spine sequence 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, oral shield longer than wide, ventralmost and 2 nd ventral spine longest, longer than an arm segment, dorsal spines thickened, ventral ones slender, not annulated.

Holotype ZMB Ech 1815

Holotype of Ophiocoma ternispina .

COLLECTING DATA. Indonesia, Flores-Sea , Larantuka, Flores, 8° 21.4’ N 122° 57.817’ E (from atlas), 1 spm.

MORPHOLOGICAL DATA. 16 mm dd, disc light brown, triangular brown spots and curved lines on DAPs, spines weakly annulated, DAP W:L 2:1, disc irregular round, ventral interradii completely granulated, arm spine sequence 3, 3, 3, (3)4, 4, 4, (4)3, 3, 3, 3, 3, 3, 3, 3, 3,3, 3 (numbers vary between arms), 2 nd ventral spine longest, slender spines, oral shield twice as long as wide.

Syntype SMNH-Type-5244

Syntype of Ophiocoma insularia .

COLLECTING DATA. Hawaii, 1860, 1 spm (originally donated to Stockholm by Museum of Comparative Zoology at Harvard).

MORPHOLOGICAL DATA. 17.6 mm dd, disc light brown marbled, arms light brown, dorsal and ventral side similar in colour, disc fully granulated dorsally and ventrally. No annulations on arm spines, spine sequence 3, 3, 3, 4, 4, 4, 5(4), 5(4), 5(4), 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3 (two arms with only 4 spines). Oral shield oval. Granule density 96-120 mm-2.

Syntypes MCZN 1668

Syntypes of Ophiocoma insularia .

COLLECTING DATA. Hawaii, Maui, 1860, 7 spms.

MORPHOLOGICAL DATA. 13.3-16.6 mm dd, all dark brown to black on dorsal disc and arms, including spines, ventral side slightly lighter brown. Both middle spines about equal, longer than dorsal and ventral spines. (Photos provided by Adam Baldinger, MCZN).

Syntypes MCZN 1666

Syntypes of Ophiocoma insularia .

COLLECTING DATA. Hawaii, 1860, 2 spms.

MORPHOLOGICAL DATA. 19.5 and 31.6 mm dd, dark brown disc and arms, with lighter abraded patches on dorsal disc, dark brown on ventral disc and arms; a note among the labels reads “4-5 spines, 3 upper about equal”. (Photos provided by Adam Baldinger, MCZN).

Other material examined

SMNH- 133232

COLLECTING DATA. La Réunion, Etang Salé, 21°16’17” S 55°19’56” E, collectors E. Boissin, T. Hoareau, 24 Feb. 2009, 1 spm.

MORPHOLOGICAL DATA. 11 mm dd, dorsal disc with a brown multipointed star-shape, white centre spot with brown dots, interradii white with brown marbled pattern ( Fig. 2E ); dorsal arm white with rectangular dark brown outlines, spines brown at base, fading into white towards their tip. Ventral interradii brown and white marbled, fully granulated to oral shields, oral frame white, oral shields with 2 parallel longitudinal brown lines. Ventral arm white with median brown dots and short lines. Arm spine sequence 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3. Granule density 216-224 mm-2.

Dorsal disc granule diameter 49-54 µm, granule density 120-144 mm-2, on SEM image ( Fig. 4F, H ); third spine on proximal segments 1 mm long, DAPs 1.4-1.6 mm wide Fig. 4G ). Oral shields as wide as long; 5-6 tooth papillae, 5 lateral oral papillae at each jaw edge, outer papilla widest ( Fig. 4I ). Few granules on proximal ends of oral plates. Oral plates, adradial distal part with strong folds, abradial face with large muscle flange with horizontal striations ( Fig. 5B ), 1.6 mm wide, 2.0 mm high. Dental plate short, externally with two large tooth foramina in dorsal half, dorsalmost foramen oval, wider than long, other foramen square; internally each foramen divided by a wide septum, dorsalmost one into two wide vertical oval slits (septum broken), other foramen into two short parallel holes ( Fig. 5E ). External ventral half of dental plate with smooth horizontal ridges, forming two wide ovals, the ventralmost one half the size of the other; a cluster of tiny depressions at ventral end of plate ( Fig. 5E 1 ). Radial shield triangular with concave proximal edge, internally with distal round condyle ( Fig. 5H ), not as ball-like pronounced as in O. brevipes and O. krohi sp. nov. Adradial genital plate ( Fig. 5K 1 ) long, flat, thin, thickened at distal end, with condyle and pit; abradial genital plate ( Fig. 5K 2 ) thin, blade-like, curved distally. Proximal vertebrae 1.6 mm wide and 1.2 mm high ( Fig. 5N ).

URUN 2009-11047

COLLECTING DATA. La Réunion, Etang Salé, 21°16’17” S 55°19’56” E, collectors E. Boissin, T. Hoareau, 24 Feb. 2009, 1 spm.

MORPHOLOGICAL DATA. 23.7 mm dd, dorsal disc uniformly reddish brown ( Fig. 2F ), dorsal arm dark brown, ventral disc and arms dark brown. Granule density 44-60 mm-2, granule diameter 70-90 µm. Arm spine sequence 3, 3, 3, 4, 4, 4, 4 (5), 4 (5), 4, 4, 4, 4, 4, 3, 3, 3, 3 (5 spines on one side of one arm, once at segment 7 and once at segment 8).

URUN 2007-00380

COLLECTING DATA. La Réunion, La Saline Trou d’eau, 21°06’09” S 55°14’24” E, collector G. Paulay, 2007, 1 spm.

MORPHOLOGICAL DATA. 24.2 mm dd, dorsal disc brown, dorsal arms dark brown with widely spaced light markings, spine slighter brown, ventral disc brown, oral frame lighter, ventral arms brown. Granule density 52-68 mm-2. Arm spine sequence 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3.

Remarks

The types of O. insularia are clearly all conspecific. Their colouration and large size suggest that they are also conspecific with O. dentata . Ophiocoma dentata occurs in several colour morphs, from uniformly dark brown to brown marbled discs with banded arms, and reticulated or spotted forms that resemble O. doederleini . It can always be distinguished from the latter species by the absence of annulations on the arm spines, and shorter arm spines. In addition, only the largest individuals sometimes have more than four spines on few arm segments. The conspecificity of the various colour morphs is also confirmed by molecular data (Boissin & Hoareau, unpublished). Another species currently believed to be conspecific with O. dentata is O. variegata with type locality Rodriguez Island. According to the original description ( Smith 1876), the type measured 28 mm dd and had only four arm spines, which agrees with O. dentata .

Devaney (1970) synonymized O. marmorata with O. dentata , but as we discuss below, the holotype of O. marmorata is most likely not conspecific with O. dentata .

Figures

Fig. 2. Colour variations in species of Ophiocoma (Breviturma) subgen. nov. A-C. Ophiocoma doederleini Rowe & Pawson, 1977. A. Reticulated specimen (UF5318). B. Close-up of annulated arm spines. C. Densely reticulated specimen (UF6518). D. Ophiocoma brevipes Peters, 1851 (SMNH- 133230). E-F. Ophiocoma dentata Müller & Troschel, 1842. E. Variegated specimen (SMNH-133232). F. Uniformly reddish brown specimen (URUN2009-11047). G-L. Ophiocoma krohi sp. nov. paratypes. G. With large patches (SMNH-Type-8533). H. Small irregular spots (MNHN-IE-4302). I. Star-shaped radiating pattern (SMNH-Type-8531). J. Densely mottled (MNHN-IE-4301). K. Uniformly dark brown (SMNH-Type-8536). L. Light brown, sparsely mottled (UF13938). For institution codes see main text.

Fig. 4. SEM images of three species of Ophiocoma (Breviturma) subgen. nov. A-E. Ophiocoma brevipes Peters, 1851 (SMNH-133230). A. Dorsal disc. B. Dorsal arms. C. Dorsal disc granules. D. Jaws. E. Ventral arm. F-I. Ophiocoma dentata Müller & Troschel, 1842 (SMNH-133232). F. Dorsal disc. G. Dorsal arm. H. Dorsal disc granules. I. Jaws. J. Ventral arm. K-N. Ophiocoma krohi sp. nov. paratype (SMNH-Type-8534). K. Dorsal disc. L. Dorsal arms. M. Dorsal disc granules. N. Jaws. O. Ventral arm. For institution codes see main text.

Fig. 5. SEM images of skeletal elements of Ophiocoma (Breviturma subgen. nov.) brevipes Peters, 1851 (SMNH-133230), O. (B.) dentata Müller & Troschel, 1842 (SMNH-133232) and O. krohi sp. nov. paratype (SMNH-Type-8535). A-C. Oral plates, abradial aspect at left, orientated with dorsal side up. A. O. brevipes. B. O. dentata. C. O. krohi sp. nov. D-F. Dental plates, external aspect left, internal aspect right, dorsal edge upwards. D. O. brevipes. E. O. dentata. F. O. krohi sp. nov. G-I. Radial shields, internal aspect, proximal edge upwards. G. O. brevipes. H. O. dentata. I. O. krohi sp. nov. J-L.Vertebrae from proximal part of arm, proximal aspect left, dorsal upwards. J. O. brevipes. K. O. dentata. L. O. krohi sp. nov. M-O. Genital plates, abradial plate left, adradial plate right, distal ends up (towards radial shields). M. O. brevipes. N. O. dentata. O. O. krohi sp. nov. P-R. Lateral arm plates from proximal arm, external aspect left, internal aspect right, distal end right. P. O. brevipes. Q. O. dentata. R. O. krohi sp. nov. For institution codes see main text.

Fig. 1. Phylogenetic reconstruction of Ophiocoma (Breviturma) subgen. nov. (two species of the scolopendrina group as outgroup), estimated by maximum likelihood and neighbour-joining analysis of concatenated sequences of the mitochondrial cytochrome c oxidase subunit I and rDNA 16S (in total 1125 bp). Values at branches indicate bootstrap values for maximum likelihood (above branches) and neighbour-joining (below branches). Specimen codes are resolved in the Supplementary file.