Ophiophrura 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 : 75-78

Genus Ophiophrura H.L. Clark, 1911

Figures 51, 52, 53

Ophiophrura H.L. Clark, 1911: 249

Ophiophiura (lapsus calami), Paterson, 1985: 52

Type species: Ophiophrura liodisca H.L. Clark, 1911 , by monotypy

Diagnosis. The disk is covered with numerous small, uniform scales, and a thin skin layer, evident when dried. The radial shields are small rounded plates, hardly conspicuous in dried specimens. The adradial genital plate is poorly developed, tightly articulated with the radial shield, proximally slightly curved. The abradial genital plate is very short and externally slightly conspicuous. Details of the articulations of genital plates and radial shields are unknown. The genital slits are long and conspicuous, but genital plates border only a distal third of the slits. The jaw bears numerous spiniform oral papillae, similar in shape to the small cluster of 3–4 ventralmost teeth. Two adoral shield papillae and one adjacent oral papilla of each jaw are somewhat clubshaped and flattened, 2–3 times longer and thicker than the oral papillae; they are placed around the second tentacle pore. The dental plate is small and elongated, without folds and with few rounded sockets, alternately placed. The teeth are spiniform and few in number (besides the ventralmost ones there are 4–5 teeth). All teeth are of similar shape. The oral shield is rhomboidal with a distinct distal lobe. The adoral shields have distal bilobed wings, proximally tapered. Dorsal and ventral arm plates are well developed. Arm spine articulations are placed distinctly at an angle in relation to the lateral arm plate. Muscle and nerve openings are similar in size or the muscle opening is slightly larger. There is a prominent perforated distal lobe occupying the dorsal part of the articulation. The sigmoidal fold is absent. The arm spines are relatively long, club-shaped or slightly flattened, hollow over almost their entire length, not hooked distally. Two elongated tentacle scales with pointed ends are placed on the lateral arm plate and one or two on the ventral plate, forming a characteristic pattern. The vertebrae have a rounded distal keel; the dorsal medial suture is indistinct. The articulation is zygospondylous. The podial basins are large.

Material studied. Ophiophrura liodisca H.L. Clark, 1911 , Holotype USNM 25672 ( Figs 51; 52C, G); Ophioprium imperfectum H.L. Clark, 1915 , Holotype MCZ 2167 ( Figs 52F, H–J); Ophioscolex tripapillatus Stöhr & Segonzac, 2005 , Paratype NI-1016 ( Fig. 53).

Remarks. Previously, only few specimens of the type and only species, Ophiophrura liodisca , were known. An additional specimen recently described by O’Hara and Stöhr (2006) differs from the type specimen. For instance, H.L. Clark (1911) described spiniform “oral tentacle scales”, whereas in the specimen described by O’Hara and Stöhr (2006) these papillae are flattened and spatulate. In this respect this specimen possibly represents a separate undescribed species.

“ Ophioprium ” imperfectum H.L. Clark, 1915 is very different from the type species of the genus Ophioprium , O. cervicornis , as was already mentioned by Clark (1915). In the present study, O. liodisca was examined in detail ( Fig. 51). Ophiophrura is characterized by two pairs of well-defined adoral shield papillae, spiniform teeth, three to four spiniform tentacle scales and hollow spines. All these features are present in the holotype (MCZ 2167) of “ Ophioprium ” imperfectum H.L. Clark, 1915 ( Figs 52F, H–J), which is therefore considered as second species of the Ophiophrura . The recently decribed Ophioscolex tripapillatus Stöhr & Segonzac, 2005 differs considerably from the type species of both genera Ophioscolex s.str. and Ophiolycus (see the diagnoses below) in having hollow spines, 3–4 elongate tentacle scales, well-defined dorsal arm plates (including proximalmost segments), flattened adoral shield papillae and a lack of hooked distal arm spines ( Figs 52A–B; D–E; 53). All these characters corresponded well with the type species of the genus Ophiophrura , according to the re-examintion of the type material of O. liodisca . Spine articulations of Ophioscolex tripapillatus are not ophiacanthid ( Stöhr & Segonzac, 2005; present study, Figs 53A–E) and differ greatly from the types species of both genera Ophioscolex and Ophiolycus but are similar to Ophiophrura liodisca . According to the present SEM study of an Ophioscolex tripapillatus paratype, the spine articulations possess a conspicuous distal lobe and are smilar to Ophiophrura liodisca articulation pattern (compare Figs 51H–I and 53A–E). Ophioscolex tripapillatus is therefore considered to be within the genus Ophiophrura .

Number of species: 3.