Ophiactis profundi Lütken & Mortensen, 1889

Nethupul, Hasitha, Stöhr, Sabine & Zhang, Haibin, 2022, New species, redescriptions and new records of deep-sea brittle stars (Echinodermata: Ophiuroidea) from the South China Sea, an integrated morphological and molecular approach, European Journal of Taxonomy 810 (1), pp. 1-95 : 68

Ophiactis profundi Lütken & Mortensen, 1889

Figs 38–39

Ophiactis profundi Lütken & Mortensen, 1889: 140–142 , pl. 6 figs 4–6.

Ophiactis pteropoma H.L. Clark, 1911: 134 , fig. 50.

Ophiactis pteropoma – H.L. Clark 1915: 264. — Matsumoto 1917: 154.

Ophiactis profundi – Koehler 1922a: 192, pl. 63 fig. 8. — Guille 1981: 439. — Liao 2004: 235–236, fig. 139.

Material examined

CHINA • 1 spec.; South China Sea , SE of Zhongsha Islands, seamount; 13°58.65′ N, 114°52.09′ E; depth 1550 m; 25 Sep. 2020; collection event: stn SC013; MSV Shenhaiyongshi leg.; preserved in 95% ethanol; GenBank: MZ 198771 ; IDSSE EEB-SW0017 • 1 spec.; same collection data as for preceding; GenBank: MZ 198772 ; IDSSE EEB-SW0018 • 5 specs; same collection data as for preceding; IDSSE EEB-SW0064 to EEB-SW0068 .

Remarks

Ophiactis profundi is a hexamerous, fissiparous species. The disc diameter ranged from 4 mm to 6 mm and all the specimens were found at one station on a deep-sea seamount in the South China Sea. Morphological descriptions of the holotype of Ophiactis profundi ( Lütken & Mortensen 1889) from the eastern Pacific Ocean and of other specimens from the Philippine Sea ( Koehler 1922a) were similar to our specimens ( Fig. 38 ).

The dorsal arm plates are well-developed, widely triangular ( Fig. 39A ). The lateral arm plate has three well-developed arm spine articulations, formed by two subparallel bent lobes, not connected to each other, placed at an angle to the distal edge and equal in size, with two similar openings for muscle and nerve ( Fig. 39B–C ). The vertebrae have a well-developed zygospondylous articulation, with a narrow, shallow dorsal furrow, not extending beyond the distal articulation, and the ambulacral groove is distalwards widened ( Fig. 39D–F ).

Ophiactis profundi is closely related to Ophiactis flexuosa Lyman, 1879 , but it differs in the shape of the oral shield and ventral arm plate, the shape of the oral papillae and the number of arms ( O. flexuosa is pentamerous). Ophiactis flexuosa has distinct scales all around the radial shields ( Lütken & Mortensen 1889). Ophiactis plana Lyman, 1869 is related to O. profundi , but it differs in the shape of the adoral shields and oral shield, and in the smaller oral papillae.

Distribution

231–1644 m. From the South China Sea recorded from the Lubang Islands near the Philippines (this part of the South China Sea is sometimes called the West Philippine Sea), East China Sea, Bohol Sea, Gulf of Tomini, Bismarck Sea, Coral Sea, Australia and New Zealand ( OBIS 2021).

Figures

Fig. 38. Ophiactis profundi Lütken & Mortensen, 1889 (IDSSE EEB-SW0017).A. Dorsal disc.B. Ventral disc. C. Radial shields. D. Oral frame. E. Dorsal arm. F. Ventral arm. G. Lateral arm. Abbreviations: ars = arm spine; as = adoral shield; dap = dorsal arm plate; gs = genital slit; os = oral shield; rs = radial shield; tp = tentacle pore; ts = tentacle scale; vap = ventral arm plate. Scale bars: A–B = 1 mm; C, G = 500 µm; D–F = 200 µm.

Fig. 39. Ophiactis profundi Lütken & Mortensen, 1889, SEM (IDSSE EEB-SW0017). A. Dorsal arm plate. B–C. Lateral arm plate (external, internal). D–G. Vertebrae. D. Proximal view. E. Distal view. F. Ventral view. G. Dorsal view. Abbreviations: D = dorsal; Dist = distal; dl = dorsal lobe; mo = muscle opening; no = nerve opening; Prox = proximal; V = ventral; vl = ventral lobe. Scale bars = 300 µm.