Amphiophiura distincta ( Koehler, 1904 )

Stöhr, Sabine, 2011, New records and new species of Ophiuroidea (Echinodermata) from Lifou, Loyalty Islands, New Caledonia, Zootaxa 3089, pp. 1-50 : 26

Amphiophiura distincta ( Koehler, 1904)

Figure 10 J– O

Ophioglypha distincta Koehler, 1904: 44 , pl. 9 figs 7–9.

Amphiophiura distincta – Matsumoto 1915: 78; Koehler 1930: 224 –5.

Material. Sta. 1461: 2 spms; sta. DW1648: 8 spms; sta. DW1650: 15 spms, sta. DW1650C: 10 spms.

Description. At 5.5 mm dd dorsal disk covered by a large primary rosette and two overlapping rounded plates interradially. Distal to radial primary plates two smaller half-circle shaped plates frame a wider wedge-shaped plate, separating the radial shields proximally. Radial shields round, slightly narrower at proximal ends, same size as primaries, stereom with larger holes. Dorsal arm plates wide triangular to fan-shaped with convex distal edge, slightly domed, separated. Lateral arm plates larger than dorsal plates, bearing up to seven short conical spines.

Ventral disk covered by large oral shields and a mosaic of smaller tumid plates. Oral shield constricted proximal to its mid-line, distally oval, proximally angular. Adoral shields narrow, abutting only proximal angle of oral shield. Jaws with pointed apical papilla, two similar pointed papillae to either side of dental plate, three wide, low lateral papillae along each side. First tentacle pore superficial, encircled by 7–8 low scales.

Bursal slits extend from adoral shields to disk edge. Abradial genital plate with spiniform papillae along entire length, distally spines elongated, forming an arm comb.

Ventral arm plates tumid, pentagonal, stereom with pores and transverse grooves, about as long as wide, on first joints rectangular, separated from fourth joint. Tentacle scales on lateral plates hardly distinguishable from arm spines, on proximal joints round, scale-like tentacle scales on ventral plate, further out only spiniform tentacle scales on lateral plate. Lateral plates on ventral side with holes.

Remarks. Amphiophiura distincta is superficially similar to A. confecta , but can be distinguished by a greater number of dorsal disk plates, more numerous and spiniform arm spines, and differences in the ventral disk scales. The oral shields approach the shape of A. confecta in some specimens.

Distribution. Type locality is Indonesia at 216 m and 794 m ( Koehler 1904). It is a new record for New Caledonia.

Figures

FIGURE 10. SEM images, A – I, Amphiophiura confecta. A, dorsal aspect; B, interadial disk dorsolateral aspect; C, dorsal arm; D, lateral arm; E, ventral aspect; F, oral details; G, ventral arm; H, arm spine articulation on lateral plate; I, dorsal arm spine. J – O, Amphiophiura distincta. J, dorsal aspect; K, dorsal arm, L, ventral aspect; M, oral details; N, ventral arm; O, arm lateral aspect. Scale bars in millimetre.