Stephanometra tenuipinna (Hartlaub)

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) : -

Stephanometra tenuipinna (Hartlaub)

(Pl. II. Fig. d)

1890. Antedon tenuipinna Hartlaub. C. (1890) Nachrichten von der Königlichen Gesellschaft der Wissenschaften und der Georgs- August-Universität zu Göttingen no. 5:178

1908. Himerometra echinus Clark, A.H. Smithsonian Misc. Colln. 52: 218. WoRMS

1971. Stephanometra echinus : Clark, A.M. and Rowe, F.W.E. Monograph of Shallow-water Indo-west Pacific echinoderms, p. 24 (key), p. 8-9 (Distribution).

2019. Stephanometra tenuipinna : Messing, C. WoRMS

Material: KV-N18. Dt. 03.12.2018. One spec. KVW-8. Dt. 04.12.2018. One spec. MCY-N18-137. Dt. 28.11.2018. 23 specs.

Description: Arms 37, 125 mm long. First brachial syzygy at 3+4, Second brachial syzygy beyond 10 segments at 15+16 or 16+17. P 1 on second segment. P 2 stout and largest. Proximal pinnules long stiff and erect, P 3 onwards somewhat soft, flexible and curved. Division series up to IVBr, well separated, of 2 segments, IIIBr and IVBr when present on outer side only. Cirri 35, cirrus segments 28, longest cirrus 31 mm long distal segments from about 8-10 or distal half with median thickening or spine like. Cirri 35+127 distal segments with a median dorsal thickening.

Remarks: Based on the key of Clarck and Rowe (1971, p. 24, note 26- tenuipinna with only 24 arms, 70 mm long and echinus with 28-40 arms, 85mm long) some specimens were initially identified with S. echinus . It was considered that the species was probably based on a larger specimen of S. tenuipinna (Hartlaub) and both the species appear to be sympatric at Sri Lanka area (? Gulf of Mannar), East Indies and The Philippines ( tenuipinna also from South Pacific Is). The length of arms maximum 70 mm in tenuipinna and minimum 85 mm in echinus suggest the differences are small and IIBr is rarely developed, while arm length 85 mm onwards IIBr and sometimes IVBr are developed. Based on WoRMS both are here treated as S. tenuipinna .

Distribution: Lakshadweep. Elsewhere: Sri Lanka area (Gulf of Mannar?), East Indies, The Philippines and South Pacific Islands. This is the first report of the species from Lakshadweep and new to Indian fauna.