Ophiactis abyssicola (M. Sars, 1861 )

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 : 33

Ophiactis abyssicola (M. Sars, 1861)

Fig. 13C–D

Amphiura abyssicola Sars, M., 1861: 18 pl. 2(7–12).

Ophiactis poa Lyman, 1879: 40 , pl. 13(356–358).— Lyman 1882: 119, pl. 20(13–15) [according to Clark, H.L. 1918].

Ophiactis abyssicola .—Clark, H.L. 1923: 334–335.— Mortensen 1933a: 347.— Olbers et al. 2019: 247–249, fig. 250–251.

Material examined. MD 50 CP7, MNHN IE.2009.1580 (43). MD 50 CP19, MNHN IE.2009.1581 (2). MD 50 DC49, MNHN IE.2009.1582 (5). MD 50 CP50, MNHN IE.2009.1583 (7). MD 50 DC64, MNHN IE.2009.1584 (5). MD 50 CP113, MNHN IE.2009.1585 (1). MD 50 CP124, MNHN IE.2009.1586 (2). MD 50 CP145, MNHN IE.2009.1587 (1). MD 50 CP152, MNHN IE.2009.1588 (8). MD 50 CP178, MNHN IE.2009.1589 (8).

Distribution. Arctic (27–2298 m), NW Atlantic (3465– 3465 m), NE Atlantic (607–4813 m), W Atlantic (1054– 1067 m), E Atlantic (425–2075 m), S Africa (415–2743 m), S Australia (932–1151 m). SPA (750–2000 m).

Remarks. A phylogeographical study of mitochondrial COI DNA ( O’Hara et al. 2014) showed that the species previously identified as Ophiactis abyssicola contained three separate species-level taxa. Ophiactis abyssicola occurred throughout the Atlantic from the Arctic to South Africa and around as far as the Atlantis seamount (32.71°S, 57.24°E) on the SW Indian Ocean Ridge. Ophiactis cuspidata Lyman, 1879 (here recognised as a full species) occurred around SE Australia, New Zealand and the Macquarie Ridge in depths of 200–1700 m. Ophiactis amator Koehler, 1922b occurred at depths of ~ 1700–4000 m off Southern Australia and New Zealand. Lower bathyal and abyssal (> 2000 m) specimens were not sequenced from the Atlantic or South Africa and so it is unclear whether a separate deep-water species occurs there (for which the name O. canotia Lyman, 1879 is available). Here the SPA population is assumed to be O. abyssicola due to its relative proximity to the Atlantis Bank compared to the nearest population of O. cuspidata off SE Australia.

Figures

FIGURE 13. (A–B) Ophiomyxa vivipara, MNHN IE.2009.1606, A: dorsal and B: ventral views. (C–D) Ophiactis abyssicola, MNHN IE.2009.1582, C: dorsal and D: ventral views. (E–I) Amphiura remota sp. nov., holotype, MNHN IE.2019.4748, E: dorsal outline, F: dorsal, G: ventral views, with H: an inset showing the denticulate disc scales. (I-J) MNHN IE.2009.1537 (non type), I: ventral view of four-rayed specimen, J: inset showing the lateral thorn at the arm spine tip.