Ophiologimus H.L. Clark, 1911

Martynov, Alexander, 2010, Reassessment of the classification of the Ophiuroidea (Echinodermata), based on morphological characters. I. General character evaluation and delineation of the families Ophiomyxidae and Ophiacanthidae 2697, Zootaxa 2697, pp. 1-154 : 68-70

Genus Ophiologimus H.L. Clark, 1911

Figures 4M; 27 L-N; 40 I –J; 48; 49

Ophiologimus H.L. Clark, 1911: 252

Type species: Ophiologimus hexactis H.L. Clark, 1911 , by original designation

Diagnosis. The disk is covered with numerous small, uniform scales, and a thin skin layer, evident when dried. The radial shields are completely concealed by skin, small rounded plates hardly conspicuous in dried specimens in most species (including the type species). The adradial genital plate is poorly developed and the abradial genital plate is absent in most species. The genital slits are long and conspicuous, genital plate(s) lining approximately half of the slits. The jaw bears numerous very short, square or rounded oral papillae, considerably different from the 2–3 ventralmost teeth. The adoral shield papillae are very short and do not differ from other oral papillae, placed around the second tentacle pore. The half-jaws are elongate, very low. The adradial sides of the half-jaws bear a few sharp straight folds distally. The dental plate is small, elongated, without folds, with few rounded sockets, alternately placed. The teeth are spiniform and few in number (besides apical papillae there are 4–5 teeth). All teeth are of similar shape. The oral shield is broadly triangular, without distinct distal lobe, except for the madreporite. The adoral shields have distal bilobed wings, proximally tapering. The dorsal and ventral arm plates are well developed. The arm spine articulations are placed distinctly at an angle or almost transversally in relation to the lateral plate. Muscle and nerve openings are similar in size. There is a prominent perforated lobe, occupying the dorsal and distal part of the articulations. The sigmoidal fold is absent. The spines are relatively long, flattened, hollow over almost their entire length, hooked distally. Two or one flattened tentacles scales with pointed ends are placed on the lateral arm plate. The vertebrae have a rounded distal keel, the dorsal medial suture is indistinct. The articulation is zygospondylous. The podial basins are large.

Remarks. The genus Ophiologimus , traditionally placed within the family Ophiacanthidae externally similar to one of the ophiomyxid genus, Ophyolycus, which is in turn often considered as just a synonym of the genus Ophioscolex (see below). Ophiologimus distinguishes from the Ophiolycus by the short oral and oral shield papillae, all similar in size (Ophyolycus has long spiniform oral shield papillae), well defined dorsal arm plate throughout the arm length (Ophyolycus possesses well defined dorsal arm plates only proximally) and entirely hollow arm spines ( Ophiolycus has almost solid spines with small holes).

Material studied. Ophiologimus hexactis H.L. Clark, 1911 , holotype USNM 25724 ( Fig. 48); Ophiologimus quadrispinus H.L. Clark, 1925 , USNM E 06912, 4 specimens, USNM E 06911, one specimen ( Fig. 49); Ophiologimus secundus Koehler, 1914 , 4 syntypes USNM 032302; Ophiologimus cf. secundus, ZMMU D-814, one specimen, ZMMU D-814, 4 specimens ( Figs 4M; 27L–N; 40I–J)

Number of species: 4.