Ophiarachna mauritiensis de Loriol, 1893a

Okanishi, Masanori & Fujita, Yoshihisa, 2019, A comprehensive taxonomic list of brittle stars (Echinodermata: Ophiuroidea) from submarine caves of the Ryukyu Islands, southwestern Japan, with a description of a rare species, Dougaloplus echinatus (Amphiuridae), Zootaxa 4571 (1), pp. 73-98 : 89

Ophiarachna mauritiensis de Loriol, 1893a

[New Japanese name: Mauritius-kumohitode]

( Fig. 9H )

Ophiarachna mauritiensis de Loriol 1893a: 32 –34, 64, pl. 24, fig. 1.— Koehler 1898: 120; 1922: 335, 336.— Bergmann 1900: 373.— H. L. Clark 1909: 128; 1915: 300.— A. M. Clark & Rowe 1971: 123.— Price & Rowe 1996: 78.

Material examined. Ie Island (RUMF-ZE-02069[1], RUMF-ZE-02070[1], RUMF-ZE-02071[1]): “entrance” of the “Unnamed cave”, under coral rubble, approximately 18 m depth, 24 June 2017.

Distribution. Japan, Mauritius. Depth range 18– 370 m.

Remarks. A. M. Clark & Rowe (1971) showed three color types of Ophiarachna . Our examined specimens (RUMF-ZE-02069, 0 2070 and 02071) present intermediate feature between the type “A” and type “C”. Aboral disc of our specimens are dull brown with a few widely scattered small dark spots like type “A”, but they also have four distinct longitudinal dark lines on aboral arm like type “C”. A. M. Clark & Rowe (1971) suggested that type “C” is undescribed, but further investigation with richer materials of Ophiarachna is required. In this study, we tentatively identify this species as O. mauritiensis by virtue of their oral shields longer than wide ( H. L. Clark, 1909). The type material of O. mauritiensis was collected from Mauritius, Indian Ocean, and its new discovery from Japanese water is a very large extension of its range. Given that the previously known specimens of O. mauritiensis has been recorded from a depth of 370 m off Mauritius, the present Japanese specimens are likely to be a distinct taxon. Further morphological observations based on richer material are required.

Figures

FIGURE 9. Aboral views of living specimens. A, Ophiolepis superba H. L. Clark, 1915 (RUMF-ZE-02063); B, Ophiozonella cavernalis Okanishi & Fujita, 2018a (RUMF-ZE-02064); C, Ophiostriatus sexradiatus irimura, 1993 (RUMF-ZE-02067); D, Ophiocoma pusilla (Brock, 1888) (RUMF-ZE-02083); E, Cryptopelta cf. callista H. L. Clark, 1938 (RUMF-ZE-02068); F, Ophiarachnella gorgonia Müller & Troschel, 1842 (RUMF-ZE-02073); G, Ophiopsammus anchista (H. L. Clark, 1911) (RUMF-ZE-02079); H, Ophiarachna mauritiensis de Loriol, 1893a (RUMF-ZE-02070).