Indophioderma ganapatii, Sastry & Marimuthu & Rajan, 2019

Sastry, D. R. K., Marimuthu, N. & Rajan, Rajkumar, 2019, Echinodermata of Lakshadweep, Arabian Sea with the description of a new genus and a species, Records of the Zoological Survey of India 119 (4) : -

Indophioderma ganapatii sp. nov.

(Pl. IX. Fig. a, b; Pl. X. Fig. a, b)

Holotype: ZSI/GNC/E2160/2, by present designation collected by N. Marimuthu on 06.02.2018 from Agatti Is.

Description of the Holotype (ZSI/GNC/E2160/2): The specimen measures 7mm in disc diameter; arm length 25mm; disk plates, radial shields, ventral inter-radial disk granule covered; radial shields not discernible. Dorsal arm plates longer than broad, with a broad distal border and a narrow proximal border (no granulation on arms). Lateral arm plates with 8 to 10 short adpressed spines shorter than the length of the arm plate. Arms on dorsal side appear to be brown, every third to six dorsal arm plate and lateral arm plates with darker proximal border giving a banded appearance. Oral plates, oral shields and supplementary oral shields completely naked. No dental papillae. Oral papillae about 10 on each side, the distal 2 to 3 extending on the lateral oral plates are broader while the rest are tapering or spine like. Oral shields somewhat triangular with curved distal edge, supplementary oral shields are round with the straight proximal border adjoining the oral shield. Ventral arm plates as long as broad with a rounded distal border; uniformly pale in the preserved specimen without banded appearance. Tentacle scale single. Genital opening single, one on each side of the arm (Genital Opening not subdivided).

Differentiation: This specimen does not fit into the key given by Clark and Rowe (1971) or the Synoptic Key for Ophiodermatidae of Fell (1961). The present specimen differs from Ophiurodon, Ophiuroconis, Toporkovia , Ophiochaeta and Ophiarachna by having adpressed arm spines. In the genera with adpressed arm spines and single tentacle scale, Ophioconis , Cryptopelta , Bathypectinura, Ophiopaepale and Schizoderma oral shields are covered by granules. In the genera, Diopoderma, Ophiocryptus, Ophioncus and Ophioderma there are two tentacle scales and the genital clefts are subdivided with 4 aperturesin each inter radius. Ophiochaeta has spines on disc scales. Among the genera with only granule covered disc scales, the radial shields are naked in Ophiarachnella and Ophiochasma . Ophiopezella has some enlarged plates onthedisc and margin. In Ophiocormus arm plates are concealed by granulation and Ophioclastus has supplementary arm plates. Supplementary oral shields are present in Distichopus and Pectinura . Ophiopeza has enlarged disc scales with enlarged granulation and supplementary oral shields. Ophiopsammus (synonym of Ophiopeza as per Fell, 1961 but valid as per Clark and Rowe, 1971 and WoRMS) has carinated dorsal arm plates (Clark and Rowe, 1971: 127, key). Thus the new genus is very close to Bathypectinura, Ophiopaepale and Schizoderma . However the arm spines are only 3-4 in all the three genera. Further the radial shields are partly exposed and granulation is comparatively very fin in Bathypectinura , and the ventral arm plates are subdivided in the other two genera We therefore propose to describe a new genus and species with the following diagnosis to accommodate the present specimen.

Etymology of the specific nomen: The species is named after late Prof. P. N. Ganapati who initiated the first author into study of echinoderms.