Ophiosabine cuspidata ( Lyman 1878b ) O’Hara & Thuy, 2022

O’Hara, Timothy D. & Thuy, Ben, 2022, Biogeography and taxonomy of Ophiuroidea (Echinodermata) from the Îles Saint- Paul and Amsterdam in the southern Indian Ocean, Zootaxa 5124 (1), pp. 1-49 : 18

Ophiosabine cuspidata ( Lyman 1878b) comb. nov.

Fig. 6C–E

Ophiacantha cuspidata Lyman, 1878b: 143 , pl. 10(248–250).— Lyman 1882: 191–192, pl. 15(9–10), 41(12–14).— Mortensen 1933c: 31–33, fig. 17–18(a–c), pl. 3(3–4).— Martynov & Litvinova 2008: fig. 7d.

Material examined. MD 50 DC49, MNHN IE.2009.1558 (1). MD 50 DC91, MNHN IE.2009.1559 (1). MD 50 CP152, MNHN IE.2009.1560 (2). MD 50 CP178, MNHN IE.2009.1561 (1).

Distribution. Arctic (781–1505 m), NE Atlantic (1315–2669 m), W Atlantic (274– 274 m), E Atlantic (781– 1236 m). SPA (880–1275 m).

Remarks. The new specimens are very similar to the types of O. cuspidata found off Ascension Is (781 m) on the Mid-Atlantic Ridge (see Martynov & Litvinova 2008, fig. 7D). They have relatively sparse but long elongate disc spines with thorns diverging at the tip, radial shields marked by a furrow and small exposed distal section, four oral papillae, the outmost widened (sometimes with a groove), pentagonal oral shields, with obtuse proximal margins and a large squarish distal lobe, 8–9 arm spines, and a pointed tentacle scale ( Fig. 6C–E ). The MD 50 specimens measure 6–10.5 mm dd, compared with 9 mm for the holotype ( Lyman 1882). The MD 50 specimens also have small thorns on the distal edge of the dorsal arm plates that were not recorded for the O. cuspidata types but may have been overlooked.

Martynov and Litvinova (2008) synonymised the five-armed O. cuspidata with the six-armed O. anomala . They are very similar, and mitochondrial sequence data indicates that for other Ophiosabine species, such as O. pentactis , five and six-armed specimens can be in the same clade ( O’Hara et al. 2013). However, in this instance, the holotype of O. cuspidata from Ascension Island in the South Atlantic appears to be distinct from other five-armed specimens from the North Atlantic that are close to O. anomala (see Martynov & Litvinova 2008, fig. 7C). The disc spines on the five- and six-armed O. anomala are shorter and stouter (see Martynov & Litvinova 2008, fig. 7H–I; Mortensen 1933c, fig. 18c) than shown for O. cuspidata , and here we recognise the latter as a distinct species.

Figures

FIGURE 6. (A) Ophiacantha veterna, MNHN IE.2009.1562, dorsal outline. (B) MNHN IE.2009.1563, ventral view. (C–E) Ophiosabine cuspidata, MNHN IE.2009.1558, C: dorsal outline, D: dorsal view, E: ventral view. (F) Ophiotreta spectabilis, MNHN IE.2009.1564, dorsal view. (G–H) Ophiolimna bairdi, MNHN IE.2009.1571, G: dorsal and H: ventral views.