Ophionereis Lütken, 1859

Stöhr, Sabine, 2024, Taxonomic analysis of the genital plates and associated structures in Ophiuroidea (Echinodermata), European Journal of Taxonomy 933, pp. 1-98 : 50

Genus Ophionereis Lütken, 1859

Fig. 23

Type species

Ophiura reticulata Say, 1825 .

Examined species

Ophionereis reticulata , O. porrecta Lyman, 1860 , O. degeneri (A.H. Clark, 1949) .

Oral GP

Elongated oval, flat, thin, proximal end under OS, pair not meeting (only examined in O. reticulata , but externally visible in O. degeneri and O. porrecta ). On some plates a round lateral process. Beset with small round granules/papillae at abradial edge. Large scales along the genital slit connect to oGP.

Adradial GP

Ophionereis reticulata : weakly cleaver-shaped with wavy abradial edge. Proximal half rod-like with longitudinal groove, distal half widened rectangular, protruding abradial edge wavy, articulates with ventral surface to abGP. Abradial surface with small adradial process with coarser stereom, oval hole in distal part. Distal end curved dorsalwards, dorsally rounded, no distinct condyle, but a groove, distal edge concave. Proximal ends of adGP and abGP crossing. Ophionereis porrecta : widened projection smaller, cleaver shape less obvious; distally a condylar process terminating flat. Ophionereis degeneri : cleaver shape slightly more pronounced than in O. porrecta , but not as strong as in O. reticulata ; distal condylar process and groove.

Abradial GP

Ophionereis reticulata : sabre-shaped, as long as adGP, sligthly curved, dorsal edge concave, ventral edge convex, with furrow in abradial side, distal third dorsally flattened concave, articulates to adGP, proximal end crosses adGP. Ophionereis porrecta : thin, flat, curved, distally widest with slanting edge, proximally tapered to round point. Ophionereis degeneri : similar to O. porrecta , but articular edge concave.

Oral shields

On inner surface, near distal edge a spur to either side. Madreporite in distal half inflated, with large opening, proximal half thinner (only examined in O. reticulata ).

Radial shield

Single condyle and coarser round patch at some distance proximal to condyle in all three examined species, condyle more pronounced in O. degeneri than in the others.

Figures

Fig. 23. Ophionereididae Ljungman, 1867, SEM, unless otherwise noted. A–J. Ophionereis reticulata (Say, 1825).A. Oral aspect, digital image. B–C. Micro-CT.B. Oral shield with oGP, inner view.C. abGp, adGB and RS in situ. D. abGP and adGP in situ. E. adPG, abradial aspect. F. abGP. G. Radial shield, inner aspect. H. Oral shield, inner aspect. I. Madreporite, inner aspect. J. Oral genital plates, one with round tubercle/process. K–M. Ophionereis porrecta (Lyman, 1860). K. Radial shield, inner aspect. L. adGP, abradial aspect. M. abGP. N–P. Ophionereis degeneri (A.H. Clark, 1949). N. Radial shield, inner aspect. O. adGP, abradial aspect. P. abGP. Scale bars: 0.5 mm.