Ophiomusa Hertz, 1927

Stöhr, Sabine, 2024, Taxonomic analysis of the genital plates and associated structures in Ophiuroidea (Echinodermata), European Journal of Taxonomy 933, pp. 1-98 : 21-22

Genus Ophiomusa Hertz, 1927

Fig. 6A–G

Type species

Ophiumusium lymani Wyville-Thomson, 1873 .

Examined species

Ophiomusa lymani .

Oral GP

Absent.

Adradial GP

Bar-like, dorsalwards curved, distal end flaring, with one large and one smaller, weakly domed or flat condylar process and curved groove; proximal to processes a large, nearly circular depression with coarser stereom. At middle of ventral edge, a fin-like process, which articulates with abGP.

Abradial GP

Large, as long as adGP, triangular, thick, a longitudinal ridge divides the plate in two slanting halves. Almost completely exposed on ventral disc.

Oral shields

Inner side flat, distally a triangular patch of smooth stereom with minute pores, in centre coarsely meshed stereom, proximally finer meshed. Madreporite strongly thickened, flatter smooth triangular patch distally, large central opening (externally no hydropore visible).

Radial shield

At middle of distal edge, a low condyle, bordered distally by narrow groove, proximal to condyle a circular patch with finer stereom.

Remarks

The disc skeleton of Ophiomusa lymani consists of a small number of large, tightly adjoining plates and few smaller dorsal scales. It is considered to be a paedomorphic species ( Stöhr & Martynov 2016). The abGP makes up a considerable part of the ventral disc covering. The genital slits are not obvious. The rough patches on adGP and RS seem to be positioned opposite to each other and are likely connected by muscle fibres.

Figures

Fig. 6. A–G. Ophiomusaidae O’Hara, Stöhr, Hugall, Thuy & Martynov, 2018, Ophiomusa lymani (Wyville-Thomson, 1873), SEM, unless otherwise noted. A–B. Micro-CT, adGP and abGP in situ. C. Oral shield, inner aspect.D. Madreporite, inner aspect.E. adGP, abradial view.F. abGP, adradial view. G. RS, inner aspect. H. Astrophiuridae Sladen, 1879, Astrophiura sp., adGP. Scale bars: A–G= 1 mm; H =0.1 mm.