Ophiocoma cynthiae Benavides-Serrato & O’Hara, 2008

(Fig. 3 a-f)

Ophiocoma cynthiae Benavides-Serrato & O’Hara, 2008: 51–55, fig. 1–2.— Boissin et al. 2016: 283, fig. 4a. Material examined: Agatti Island—intertidal, eastern side (10° 50.73’ N, 72° 11.35’ E), coll. U. Parameswaran on 05.11.2018 by hand, 2 specimens (CMLRE IO/SS/ECD/00229, 00230); Kavaratti Island—intertidal, eastern side (10° 30.18’ N, 72° 27.06’ E), coll. M. Nowshad on 28.11.2018, 1 specimen (MTRL/DST/E00303).

Description: D.d. up to 25 mm, disc rounded with scalloped margin; arms ~4 times d.d. Disc covered dorsally and ventrally with fine scales; dorsal side bearing large, rounded granules which are packed more densely in the centre (Fig. 3a, c); ventral side lacking armament except rounded or tall granules bordering the genital slits and oral shield (Fig. 3d). Oral shield oblong to oval, longer than broad; adoral shields, small, triangular, not contiguous radially or inter-radially (Fig. 3d). Dental plate oblong, with two foramina, the septum of the second much thicker than the first; dental papillae in three columns in the upper third of the plate (Fig. 3 e-f). Teeth square-tipped with hyaline edges; apex of dental plate with cluster of ~10 tooth papillae in three columns; one short infradental papilla on each side, followed by a leaf-like secondary adoral shield spine and a much wider adoral shield spine; Lyman’s ossicle projecting between the adoral shield spine and first ventral arm plate (Fig. 3d). Dorsal arm plates thick, fanshaped, wider than long; each overlain proximally by the preceding plate (Fig. 3c). Ventral arm plates with straight proximal margin, broadly rounded distal margin and recurved lateral margin (Fig. 3d). Arm spines two at first segment, increasing up to five, and alternating in number through much of the arm; basal arm spines flattened and long, subsequently becoming cylindrical with rounded tips; alternating dorsal-most arm spine distinctly longer and clubshaped, widest in the middle or just beyond the middle; three arm spines in the distal third of arm, all long, slender and tapering (Fig. 3 a-d). Two overlapping oval tentacle scales, decreasing to one in the distal end of arm (Fig. 3d).

Colour: In life, uniformly black with dull brownish-grey tentacles (Fig. 3b); preserved specimen black to grey, including tentacles (Fig. 3a, c-d).

Distribution: Saudi Arabia, Djibouti, Comoros, Reunion, India (Lakshadweep), Papua New Guinea, Australia, New Caledonia, Fiji, Micronesia, Philippines, Taiwan, Japan; intertidal- 26m (OBIS, 2020b).

Remarks: Ophiocoma cynthiae was separated from O. erinaceus Müller & Troschel, 1842 by Benavides-Serrato & O’Hara (2008) based on molecular evidence (O’Hara et al. 2004). The two species can be distinguished chiefly by the nature of ventral disc granulation (nearly complete in O. erinaceus and nearly absent in O. cynthiae), the colour of tube feet in live specimens (bright red in O. erinaceus and grey in O. cynthiae), and the morphology of the dental plate. Based on these characters, the present specimens from Lakshadweep clearly belong to O. cynthiae. Extensive field surveys in recent years by the authors (particularly MNB & IBKK) have observed this species (with brown-grey tentacles) commonly in all atolls of the Lakshadweep, but have not retrieved a single specimen with red tentacles (characteristic of O. erinaceus). While O. erinaceus has been reported from the Lakshadweep (Koehler 1898; Bell 1902; James 1969, 1982; Sastry 1991; Price & Rowe 1996; Sastry et al. 2019), it is possible that these actually represent records of O. cynthiae.