Ophiomora elegans Koehler 1907
Creators: name: Okanishi, Masanori
name: Oba, Yuichi
name: Fujita, Yoshihisa
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Ophiuroidea
Ophiurida
Ophiomyxidae
Ophiomora
Ophiomora elegans

description: Ophiomora elegans Koehler, 1907   
(Figs. 11B, 12, 13)  
 Ophiomora elegans Koehler, 1907: 342, 343, pl. 14; H. L. Clark, 1915: 174; Tan et al., 2014: 413; Fujita et al., 2015: 50, 97.   
 Material examined. RUMF-ZE-00142, submarine cave “ Thunderdome Cave ” at Christmas Island, northwestern Australia, depth approximately 10 m, SCUBA diving, coll. Tan Heok Hui, 27 March 2011. Partly bleached to remove integuments.   
 Diagnosis. The same as the genus.   
 Description of external morphology (RUMF-ZE-00142). Disc. Circular, 22 mm in diameter, covered by thick skin, embedding small granules, approximately 200–400 μm in length (Figs. 11B, 12A). On aboral surface, removing the skin, radial shields exposing, bar-like, 3 to 4 times longer than wide, almost reaching to disc center (Fig. 12B). Stout polygonal plates also exposing and forming a single transverse row on lateral disc margin (Fig. 12B). On oral surface, removing the skin, adoral shields trapezoid, wider than long (Fig. 12D), approximately 1 mm at outer edge and 700 μm at inner edge in length, 1 mm in width, in contact with the first ventral arm plates (Fig. 12D). Oral plates thin, approximately 800 μm in length, 400 μm in width, contacting each other. Oral shields triangular, approximately as long as wide (Fig. 12C, D). One circular oral shield serving as madreporite and having at least three pores (Fig. 12C). Interradial oral disc covered only by skin (Fig. 12C). Genital slits small, along between 3rd and 4th arm segments (Figs. 12F, 13B), approximately 200 μm in length (Fig. 12C). Abradial genital plates visible on side of genital slit, bar-like, approximately 1.5 mm in length and 0.3 mm in width (Fig. 12E). Thorny granules inside of the genital slit, near the abradial genital plates (Fig. 12E). Four flat, subequal trapezoidal oral papillae at each adoral shield horizontally (Fig. 12C, D). Teeth triangular, forming single vertical row on dental plate (Fig. 12D). Second tentacle pore completely inside the mouth slit.   
 Arms. Five, all arms entire almost entire length, 50–75 mm long. Arms approximately 4.0 mm wide and 2.0 mm high, flatten. Arms tapering and flatting gradually distally (Figs. 11B, 13A, B, D–G).   
Throughout the arm, dorsal arm plates absent and small fragmented plates, approximately 300–500 μm in length on aboral side (Fig. 13A). On distal portion of the arm, lateral arm plates contacting on mid line each other (Fig. 13B). On oral side, removing the skin, ventral arm plates polygonal, slightly wider than long, lateral sides concave, contiguous on proximal portion of the arm (Fig. 13C). On middle to distal portion of the arm, ventral arm plates triangular, pointing to proximal portion, and separated by each other (Fig. 13D). Lateral arm plates bearing arm spines, on proximal portion, 3 or 4 spines, long and pointed, and aboral-most spine approximately 1.5 times as long as corresponding arm segment, and other spines as long as corresponding arm segment (Fig. 13D, F). On middle portion of arm, 3 subequal long and pointed spines, approximately as long as the corresponding arm segment (Fig. 13G). On distal portion of arms, 2 subequal cylindrical and oval arm spines, approximately half to one-thirds length of corresponding arm segment (Fig. 13E). Tentacle scales 1, flat and fanshaped, two-thirds to the same length of the corresponding arm segment, and outer one half to one-fourth length of the corresponding arm segment throughout the arms (Figs. 12F, 13D, E).  
 Colour in life. Body basic creamy white. On aboral surface, dense orange small spots appear except proximal portion of the arm where the spots are sparsely scattered (Fig. 11B). Deep purple bands present at intervals of 6 to 8 arm segments. Oral disc also creamy white with the deep purple bands on arms continuous from aboral surface (photo not shown).   
 Common Japanese name. Gama-kumohitode.   
 Distribution. Known from the type locality, the Fernando Veloso, near Inhaca Island, southern Republic of Mozambique, eastern coast of Africa (Koehler, 1907); Kumejima Island, the Ryukyu Islands, southeastern Japan, submarine cave, approximately 18 m depth (Fujita et al., 2015); Christmas Island, northwestern Australia, submarine cave known as “Thunderdome Cave”, approximately 10 m depth (this study, Fig. 1).   
 Remarks. In original description, Koehler’s examined single specimen had a disc diameter of 13 mm, almost 10 mm smaller than our examined specimen (22 mm in disc diameter). Koehler (1907) distinguished Ophiomora from other genera in the Ophiomyxidae in having small genital slits with carrying few calcareous ossicles beside them and one tentacle scale on each tentacle pore (Koehler, 1907). These characters are also recognised in our specimen (Fig. 11E, F). Considering the distinct characters, although this genus is now incertae sedis in the order Ophiacanthida, we maintain Ophiomora as a valid genus. Our extensive second description of this species revealed that this species has radial shields, which were stated in the original Koehler (1907) as absent. However, of course, to determine the precise taxonomic position of this species, reexamination of the single type specimen of Ophiomora elegans is required.   
The sampling locality of the present specimen (Christmas Island, northwestern Australia) is located midway between the type locality (East Africa) and the recent record from Japan. This geographical evidence indicates this species is widely distributed in the Indo-Western Pacific region (Koehler, 1907; Fujita et al., 2015).
description: Published as part of Okanishi, Masanori, Oba, Yuichi & Fujita, Yoshihisa, 2019, Brittle stars from a submarine cave of Christmas Island, northwestern Australia, with description of a new bioluminescent species Ophiopsila xmasilluminans (Echinodermata: Ophiuroidea) and notes on its behaviour, pp. 421-439 in Raffles Bulletin of Zoology 67 on pages 435-436, DOI: 10.26107/RBZ-2019-0034, http://zenodo.org/record/4576271