New record of brittle star from Arabian Sea

Ophiodaphne scripta, male-female pairs, left: ventral view showing male attached to oral side of female, right: dorsal view of female

Phylum: Echinodermata

Class: Ophiuroidea Gray, 1840

Order: Ophiurida Müller & Troschel, 1840

Family: Amphiuridae Ljungman, 1867

Ophiodaphne scripta (Koehler, 1904)

Collection: SE Arabian Sea slope, off Cape Comorin-Kollam, 38-111 m. Cape Comorin – 7° 47.649′ N, 77° 30.26′ E, 52 M, 30.5.2009 (FORVSS 267I, St. 2). Trivandrum – 8° 26.014′ N, 76° 47.946′ E, 53 M, 20.11.2010 (FORVSS 282, St. 10). – 8° 27.052′ N, 76° 53.967′ E, 38 M, 30.8.2011 (FORVSS 289, St. 18). – 8° 30′ N, 76° 48′ E, 51 M, 2.9.2011 (FORVSS 289, St. 29). – 8° 30′ N, 76° 48′ E, 52 M, 4.9.2011 (FORVSS 289, St. 37). – 8° 30′ N, 76° 48′ E, 51 M, 4.9.2011 (FORVSS 289, St. 38). – 8° 30′ N, 76° 48′ E, 52 M, 5.9.2011 (FORVSS 289, St. 41). – 8° 30′ N, 76° 48′ E, 52 M, 6.9.2011 (FORVSS 289, St. 45). – 8° 30′ N, 76° 48′ E, 52 M, 7.9.2011 (FORVSS 289, St. 49). off Kollam – 9° 20.971′ N, 75° 52.841′ E, 111 M, 14.5.2010 (FORVSS 275, St. 7). Naturalist Dredge and Smith-Mcintyre Grab.

Voucher No.: CMLRE IO/SS/ECD/00071 (FORV Referral Centre, CMLRE, Kochi)

Description: Species showing prominent sexual dimorphism – with dwarf males being attached to the ventral side of the disc of the female, which is much larger.

Female – Disc diameter (d.d.) up to 4 mm and arms about 1.5 to 2 times d.d.; covered above and below with small imbricating scales; radial shields about one half of disc radius, contiguous along most of their length and separated by a few small scaled; transverse parallel grooves along inner edge or across entire surface of radial shields. Oral shields small, rhomboid with a rounded distal edge; adoral shields large; oral plates distinct; infradental papillae poorly distinguished; oral papillae more or less fused together, forming a continuous row along the sides of jaws; provided with numerous minute thorns on their edge. Oral and adoral shields along with sunken oral plates, bearing minute inwardly directed spinules. Teeth conspicuous, rounded and conical structures, 4-5 in a vertical row. Dorsal arm plates pentagonal, contiguous; ventral arm plates square, contiguous. Five rounded conical arm spines basally, 4 distally, of which the two dorsal-most are transformed into hooks; single leaf-like tentacle scale present throughout the arm. Colour white.

Male – Disc diameter up to 1 mm, arms about 4-5 times this length; slightly tumid in inter-radii.  Dorsal disc completely covered by large rounded primary rosette plates; ventral side of disc paved by small imbricating scales. Genital slits and jaw structures minute and poorly developed. As in females, a continuous row of fused, thorny oral papillae present, bearing minute thorns. Teeth rounded and conical. Dorsal arm plates fan-shaped and separated throughout arm; ventral arm plates pentagonal and separated throughout arm. Tentacle scales absent; 3 short cylindrical arm spines at the arm base; two in number and sometimes ending in glassy thorns; transformed into curved hooks at the distal arm. Colour white.

Sexual dimorphism – Apart from the obvious distinctions in size, the males and females differ significantly in skeletal elements, chiefly the number, disposition and ornamentation of dorsal disc scales; and numbers and shape of arm spines, which are described above. Tentacles scales and genital slits are altogether absent in males but present in females.

Biological association: Specimens were collected as epibionts on cake urchin Sculpsitechinus auritus (Leske, 1778).

Remarks: Rare, sexually dimorphic species represents a new record from the Indian waters

Distribution: Indian waters – SE Arabian Sea (Parameswaran et al. 2013, present study), and SW Bay of Bengal (Parameswaran et al. 2013). Elsewhere – Continental and insular shelves of the western and north western Indian Ocean.

Distribution map:

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

Identified by: Parameswaran, Usha V.

Publication: Parameswaran U. V., Abdul Jaleel K. U. & Sanjeevan, V. N. (2013) Ophiodaphne scripta (Ophiuroidea: Amphiuridae), a brittle star exhibiting sexual dimorphism and epibiosis: first record from India, with notes on adaptations, systematics and distribution. Marine Biodiversity, 43(4):333-339. DOI: 10.1007/s12526-013-0160-9.

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