Ophiopleura Danielssen & Koren, 1877

Stöhr, Sabine, 2024, Taxonomic analysis of the genital plates and associated structures in Ophiuroidea (Echinodermata), European Journal of Taxonomy 933, pp. 1-98 : 19-20

Genus Ophiopleura Danielssen & Koren, 1877

Fig. 5

Type species

Ophiopleura borealis Danielssen & Koren, 1877 .

Examined species

Ophiopleura borealis .

Oral GP

Absent.

Adradial GP

Blade-like long, dorsalwards curved, distally thicker with one weakly domed condyle and one condylar process with flat end, one circular smooth dorsal depression with thick rim (suction cup-shaped), one oval adradial embossed articular structure with coarser stereom. Ventral half thinner than dorsal.

Abradial GP

As long as adGP, weakly curved, concave dorsal surface articulating broadly to ventral abradial part and condylar process on adGP, proximal end strongly tapered to a point.

Oral shields

Inner side flat, coarse stereom. Madreporite externally with multiple small pores in distal part (not visible on inner side), inner side similar to that of regular oral shield, but large central opening, partially covered by stereom lobes.

Radial shield

Almost as long as disc radius (most of it covered by scales and thick skin in intact disc), narrow, thin, distal end widened, fragmented into several pieces of varying size during bleaching. Single low condyle on middle of distal end, distally bordered by deep groove; one nearly round, finer meshed depression proximal to condyle.

Remarks

Ophiopleura is one of the more completely developing genera of Ophiopyrgidae , not considered to be paedomorphic. In O. borealis , the adGP and abGP support the genital slit along its full length, between distal end of adoral shield and disc edge, which may explain the absence of oGPs. The radial shields are covered by disc scales, except for their distalmost part, and their appearance, rib-like and radiating from the disc center to the disc margin, as well as their tendency to break into several pieces, is similar to conditions in Euryalida , but they are considerably thinner. The shape of its genital plates is unusual among the here studied species and doesn’t convey its phylogenetic relationships.

Figures

Fig. 5. Ophiopyrgidae Perrier, 1893, Ophiopleura borealis Danielssen & Koren, 1877, SEM images. A. Dorsal disc, scales removed by bleaching. B. Bleached arm with genital plates, ventral view. C. RS, distal part, ventral aspect. D. adGP and abGP attached to each other, abradial view. E. adGP, abradial view. F. adGP, adradial view. G. abGP, dorso-lateral view. H. abGP, ventral view. I. abGP, lateral view. J. Oral shield, inner side. K. Madreporite, inner side. Scale bars: A= 10 mm; B–K =1 mm.