New record of brittle star from Andaman waters, with bathymetric range extension

Ophiomyces delata, entire organism in lateral view

Phylum: Echinodermata

Class: Ophiuroidea Gray, 1840

Order: Ophiurida Müller & Troschel, 1840

Family: Ophiohelidae Perrier, 1893

Ophiomyces delata Koehler 1904

Collection: Andaman & Nicobar Islands – Duncan Passage: 12 individuals; FORV Sagar Sampada Cruise 292, Stn. 7; 11°14.85’N 92°27.01’E, 56 m; coll. 22 November 2011, Smith-McIntyre grab & modified naturalist dredge.

Voucher No.: CMLRE IO/SS/ECD/00072 (FORV Referral Centre, CMLRE, Kochi)

Description: Disc sac-like, finely scaled, lacking radial shields, and with needle-like spines. Arms bent upwards. Oral plate obscured by flat, scale-like oral papillae arranged in four imbricating rows on their lateral, as well as ventral surface. Proximal arm segments with three tentacle scales: two borne on the ventral arm plate and one on the lateral arm plate; 8-12 arm spines in basal segments varying with specimen size.

Biological association: None.

Remarks: While members of the genus Ophiomyces are considered typical ‘deep-water forms’, the present finding represents a unique shallow-water population of Ophiomyces delata in sandy shelf sediments (56 m) off the southwest of Rutland Island in the Andamans.

Distribution: Mozambique Channel (640 m), Eastern Arabian Sea (1300–3100 m), Carlsberg Ridge (2620 m), Duncan Passage, Andaman Islands (56 m), Java Sea (210–4240 m), Sulu Sea (350–535 m), Philippine Sea (1272–4239 m), East China Sea (818–824 m), Coral Sea (656–897 m), off northern New Caledonia (375–3690 m), Tasman Sea (500–922 m), Norfolk Ridge (510–1400 m), Southwestern Pacific (northeast of New Zealand, 1028–1600 m), Southeastern Pacific Ocean (Sala y Gomez-Nazca Ridge, 170–548 m).

Distribution map:

Map showing locations of previous records (circle) and present record from Indian waters (square) of Ophiomyces delata

Identified by: Parameswaran, Usha V.

Publication: Parameswaran U. V., Abdul Jaleel K. U., Gopal A.,  Sanjeevan V. N. & Anil Kumar V. (2015) On an unusual shallow occurrence of the deep-sea brittle star Ophiomyces delata in the Duncan Passage, Andaman Islands (Northern Indian Ocean). Marine Biodiversity, 46(1):151-156. DOI 10.1007/s12526-015-0344-6.

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