Asteroschema, Orstedt and Lutken, 1856 in Lutken, 1856

Baker, Alan N., Okanishi, Masanori & Pawson, David L., 2018, Euryalid brittle stars from the International Indian Ocean Expedition 1963 - 64 (Echinodermata: Ophiuroidea: Euryalida), Zootaxa 4392 (1), pp. 1-27 : 2

Asteroschema cf arenosum Lyman, 1878

( Fig. 1A–D )

Asteroschema arenosum Lyman, 1878: 235 , pl. 3 figs. 62–64; Barboza et al., 2010: 242; Frensel et al., 2010: 175.

Material Examined. USNM 1072539 , Pioneer Cruise 17, south of Lombok , eastern Indian Ocean, 10° 50’S, 117° 50’E, 1000 m, 17 March 1964, 3 specimens.

Remarks. These specimens were identified as A. arenosum on the basis of the disc and upper arm covering of flat polygonal plate-shaped external ossicles ( Fig. 1C ), the lateral arm cover of fine rounded granule-shaped external ossicles ( Fig. 1D ), and the presence initially of one, then two, arm spines. One complete specimen had a disc diameter of 11 mm and arms 180 mm long ( Fig. 1A–B ).

The type specimen of A. arenosum was collected in the Gulf of Mexico and its occurrence in the Indo-Pacific region is thus a very large extension of its range. Given that this species has been recorded from a depth of 1449 m in the western Atlantic ( Pawson et al. 2009), it is likely to be a distinct taxon. However, we here refrain from describing another species here since we examined only 3 specimens. Future morphological observations and molecular analyses based on more specimens are required.

Figures

FIGURE 1. Asteroschema arenosum (USNM 1072539) (A–D) and Squamophis amamiensis (USNM 1072572) (E–H). A, aboral view; B, oral view; C, aboral disc; lateral view of distal arm; E, aboral view; F, oral view; G, aboral disc; H, oral disc. Abbreviation: AS, arm spine.