Ophiura Lamarck, 1801

Stöhr, Sabine, 2024, Taxonomic analysis of the genital plates and associated structures in Ophiuroidea (Echinodermata), European Journal of Taxonomy 933, pp. 1-98 : 14

Genus Ophiura Lamarck, 1801

Fig. 2

Type species

Asterias ophiura Linnaeus, 1758 .

Examined species

Ophiura ophiura , O. sarsii Lütken, 1855 .

Oral GP

Row of nearly vertical scales lines abradial edge of genital slit, proximalmost scale overlapped by lateral edge of oral shield, appears not to articulate or form a pair with opposite scale, hence, oPGs considered absent.

Adradial GP

Club-like long rod with bulbous distal end, at least three arm segments long, parallel to arm, distal end curving upwards to meet radial shield. Dorsal part of rod-like part round and thickened, ventral part thinner and blade-like flattened. Distal end with two ball-like condyles, differing in size, one bordered adradially by a half-circle-shaped groove, abradially by flat edge. Several depressions between condyles, a rough patch proximal to condyles on dorsal adradial edge.

Abradial GP

Roughly triangular, cup-shaped (abradially convex), with dorsal beak-like extension, much wider than adGP, two thirds as long as adGP, almost completely exposed at disc edge. Ventral adradial edge with pores, where genital papillae attach (arm comb). Articulates to adGP at right angle, creating wide gap between both GPs.

Oral shield

Madreporite with hydropore in one lateral distal edge, inner surface flat, smooth stereom, finer along edges, large opening in proximal half.

Radial shield

With two weakly domed condyles, radial one bordered by distal half-circular groove, articulating with adGP.

Figures

Fig. 2. Ophiuridae Müller & Troschel, 1840, digital (A–C) and SEM (D–P) images. A–K. Ophiura ophiura (Linnaeus, 1758). A. Mouth parts macerated in bleach, one jaw with oral shield removed, another with madreporite still attached, no oGP present. B. Radial shields and abGP in situ, dorsal view. C. adGP and abGP at arm base after removal of RS and disc, dorsal view. D. abGP, adGP, and RS, lateral view. E. abGP, adGP, RS, internal view. F. adGP, distal end, dorsal aspect. G. abGP, abradial aspect. H. Madreporite, inner aspect. I. Radial shield, inner aspect. J. abGP, outer aspect. K. abGP, inner aspect. L–P. Ophiura sarsii Lütken, 1855. L. adGP, abGP in situ, ventral view. M. adGP, abradial aspect. N. adGP, adradial aspect. O. abGP, inner aspect. P. abGP, outer aspect. Scale bars: A–E= 1 mm; F–P=0.5 mm.