Hymenaster tenuispinus $ Sibuet 1976

Hymenaster tenuispinus Sibuet, 1976 Reports for the Azores:

Hymenaster tenuispinus $ Sibuet, 1976: 289–291, fig. 3.

Type locality: off Brittany, France (47°34’N, 8°38’W).

See: Sibuet (1976); A.M. Clark & Downey (1992: 323).

Occurrence: Northeast Atlantic, from west of Brittany (France) south to North of Galicia (Spain) in the Bay of Biscay west to the Azores (Sibuet 1976).

Depth: 2,120–2,245 m (AZO: 2,120 m; Sibuet 1976).

Remarks: the relatively unknown Hymenaster tenuispinus was described by Sibuet (1976) to encompass specimens collected in the Bay of Biscay. Sibuet also identified this species among the material taken in the southwest of Flores Island by the Jean Charcot during the expedition Biacores (sta 131BL: 39°04’30”N, 32°43’30”W, 2,120 m). Recently, Dilman (2013) noted that some of the specimens collected in the Charlie-Gibbs Fracture Zone north of the Azores shared characters with H. tenuispinus and the sub-Antarctic H. coccinatus. According to Dilman, these two species differ only by the number of adambulacral and oral spines, a character that appears to be size-related. Hymenaster tenuispinus may prove to be a junior synonym based on juveniles or subadults of H. coccinatus, a species previously thought to be restricted to the waters between Marion and the Crozet Islands.