Ophiomyces Lyman, 1869

Stöhr, Sabine, 2024, Taxonomic analysis of the genital plates and associated structures in Ophiuroidea (Echinodermata), European Journal of Taxonomy 933, pp. 1-98 : 30-31

Genus Ophiomyces Lyman, 1869

Fig. 12

Type species

Ophiomyces frutectosus Lyman, 1869 .

Examined species

Ophiomyces delata Koehler, 1904 , O. frutectosus .

Oral GP

Not examined, not identified in situ. Considered absent.

Adradial GP

Flat, thin, blade-like, ventral edge convex, dorsal edge straight, articular structure at distal end as embossed oval patch with finer stereom.

Abradial GP

Similar to adGP, articular patch depressed. When both GP are articulated, they are parallel, leaving a narrow slit between them.

Oral shields

Minute, elongated drop-shaped, with thickened rectangular distal end, depressed center of OS with coarse, porous stereom in external and internal views. Madreporite similar, with several small pores in middle part.

Radial shield

Absent.

Remarks

Matsumoto (1915, 1917) considered the abradial genital plate (his “genital scale”) and the radial shield in Ophiomyces to be absent ( Table 1 ). Lyman (1882) considered the radial shield to be absent, but both genital plates to be present ( Table 1 ), and the present study confirms his interpretation. They both described the adradial genital plate as curved over the top of the arm. Instead, both genital plates are flat and straight, and in the intact disc they may be upright or diagonal across the arm base ( Fig. 12E ). Oral GPs were not found after dissociating the skeleton and may be absent, since the adGP and abGP extend the full length from oral shield to disc edge, with the genital slit opening between them. Conditions in Ophiotholia spathifer (Lyman, 1879) are the same as in Ophiomyces .

Figures

Fig. 12. Ophiohelidae Perrier, 1893.A–B. Ophiomyces frutectosus Lyman, 1869, digitalphotos.A. Lateral view. B. Detail of genital plates in situ. C–H. Ophiomyces delata Koehler, 1904, SEM. C. adGP, abradial aspect. D. abGP, adradial aspect. E. Genital plates in situ. F. Oral shield, external aspect. G. Oral shield, inner aspect. H. Madreporite, inner aspect. Scale bars: A–B =1 mm; C–E =0.5 mm; F–H=0.1 mm.