Ophiomitrella nudextrema (H.L. Clark, 1939)

Ophiacantha nudextrema Clark, H.L., 1939: 44–45, fig. 6.

Ophiomitrella nudextrema . — O’Hara & Stöhr, 2006: 126, fig. 18q.

STUDY MATERIAL. — MD208: stn DW4881, Walters shoal, Pentes, 33° 16.87´S, 43° 50.69´E to 33° 16.24´S, 43° 50.0599´E, 377–382 m, 2/5/2017: 1 (MNHN IE.2023.4175) (DNA code= IE.2023.4175) . — MD208: stn DW4890, Walters Shoal, Pentes, 33° 8.7´S, 43° 58.16´E to 33° 8.77´S, 43° 59.13´E, 492–588 m, 4/5/2017: 1 (MNHN IE.2016.1357) .

COMPARATIVE MATERIAL EXAMINED. Ophiomitrella nudextrema (H.L. Clark, 1939): John Murray /157, Maldive Is, 4° 43.48´N, 72° 55.24´E to 4° 44´N, 72° 54.18´E, 229 m, 6/4/1934, holotype, NHMUK 1948.5.26.32 . ATIMO VATAE / CP3614, Sud Cap Sainte Marie, 26° 14´S, 45° 9´E, 250–300 m, 14/5/2010 , MNHN IE.2007.4178 (DNA code= IE.2007.4178). Ophiomitrella tenuis (Koehler, 1904): EBISCO/DW2607, Plateau des Chesterfield, 19° 33´S, 158° 40.0003´E, 400–413 m, 18/10/2005 , MNHN IE.2013.6313 (DNA code=IE.2013.6313).

Distribution. Maldives (229 m); Madagascar (250–333 m); Walters Shoal (377–588 m).

Remarks. The 3 mm dd holotype of this species is characterised by a pentagonal disc; separate broadlytriangular radial shields, with slightly concave sides, naked; disc granules small stumps, centrally becoming trilobed with minute terminal thorns, disc stumps near the marginal interradial midline become lengthened; to 8 short slender arm spines, uppermost to 2 segments in length, lowermost with some thorns; LAPs striated; 3–4 lateral oral papillae; oral shields 2x as wide as long; one oval tentacle scale with a rough tip, to 1/2 segment in length. The MD208 (2–3.5 mm dd) specimens are similar, except the smallest (IE.2016.1357, 2 mm dd) has only one elongated disc stump on the interradial slide of the radial shields. The ATIMO VATAE specimen has some taller disc stumps near the centre of the disc also. This species is sister to Ophiomitrella tenuis from the East Indo-West Pacific.