Ophiomedea Koehler, 1906

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 : 73-75

Genus Ophiomedea Koehler, 1906

Figure 50

Ophiomedea Koehler, 1906:19

Type and single species: Ophiomedea duplicata Koehler, 1906 , by monotypy Diagnosis. The disk is covered with numerous small, uniform scales, not concealed by a skin layer. Both dorsal and ventral sides of the disk are covered with numerous relatively long spinelets. The radial shields are small, triangular, hardly conspicuous plates. The adradial genital plate has well-defined lateral wing, and a small but distinct condyle separated by a shallow groove. Abradial genital plate not detected. The genital slits are short and only slightly evident. The jaw bears three or four pairs of spiniform oral papillae, very different from the shape of the massive, wide, single ventralmost tooth. There is the pair of long spiniform adoral shield papillae, 2–3 times longer and markedly different from the other oral papillae, placed around the second tentacle pore. The dental plate, judged from the massive teeth morphology should bear few slit-shaped sockets. The oral shield is markedly wider than long, oval, with a small proximal and a more or less distinct distal lobe. The adoral shields are broad bands, of uniform shape throughout. The dorsal and ventral arm plates well developed. The dorsal arm plates are small, triangular, with almost straight distal edge, and contiguous. The muscle opening is larger than the nerve opening. There is a volute-shaped, perforated lobe, occupying the dorsal and distal parts of the articulations. The sigmoidal fold is well-defined. The spines are relatively long, rounded, contain small lumens inside, not hooked distally. The tentacle scales are small and conical, one or two in number, placed both on the lateral and ventral plates, or absent. The tentacle pores are relatively large.

Material studied. Ophiomedea duplicata Koehler, 1906 , holotype MNHN, EcOs 20426 ( Fig. 50).

Remarks. Koehler (1922a) has included into the genus Ophiomedea two other species, one initially described within a separate genus Ophiophrura H.L. Clark, 1911 (with type species O. liodisca H.L. Clark, 1911 ) and Ophiomedea discrepans Koehler, 1922 , an abyssal species from the Philippine region. Holotypes of both Ophiophrura liodisca and “ Ophiomedea ” discrepans were examined ( Figs 51 and 63) and compared with the holotype of Ophiomedea duplicata Koehler, 1906 (EcOs 20426) ( Fig. 50). It was revealed that all three taxa differ considerably from each other and do not show any close similarity. Ophiomedea duplicata is a true ophiacanthid, with spine articulations possessing a volute-shaped lobe ( Figs 50F, G) and the sigmoidal fold and massive wide teeth, whereas both Ophiophrura liodisca and “ Ophiomedea ” discrepans show nonophiacanthid articulation and spiniform teeth ( Figs 51H, I; 63G, H).

Ophiomedea duplicata is currently known only from a single specimen from the type locality in the North Eastern Atlantic , off Canary Ids, at 2075 m .