Ophiodaces Koehler, 1922

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 : 64-65

Genus Ophiodaces Koehler, 1922

Ophiodaces Koehler, 1922b: 24

Type and only species: Ophiodaces inanis Koehler, 1922 , by monotypy

Ophiodaces inutilis (lapsus calami): Koehler, 1922b: 89, legend to Plate 78, figs 6–8

Non Ophiodaces sensu Fell, 1960: 15

Diagnosis. The disk scales are obscured by a moderately developed skin layer. The radial shields are very large, partially concealed by skin in some interradii. The genital plates (judged from external morphology) are well developed. The genital slits are long, genital plates possibly bordering almost the entire length of the slits. The jaw bears numerous spiniform oral papillae similar in shape to the small cluster of ventralmost teeth. Two pairs of the adoral shield papillae are massive, conical, markedly different in shape and length (approximately 2 times longer than the oral papillae), placed around the second tentacle pore. The teeth are spiniform, which suggests that the dental plate should have small rounded sockets. All teeth are similar in shape. The oral shield is strongly convex distally and markedly triangular proximally, no distinct distal lobe. The adoral shields are similar in size distally and proximally. Dorsal and ventral arm plates are well developed. The dorsal arm plates are oval, with straight edges both distally and proximally, contiguous. The dorsal arm plates are entire proximally. The ventral arm plates are contiguous, with a convex distal and straight proximal edge. The spines are relatively short, conical. One small conical tentacle scale is placed on the lateral arm plate.

Remarks. The type of Ophiodaces inanis Koehler, 1922 was not examined (according to Rowe, Pawson, 1977, is in the Australian Museum). Fell (1961) discovered a smaller specimen that he identified as Ophiodaces inanis , but this specimen differs considerably from Koehler’s (1922b) description in having a small rounded radial shield, inconspicuous skin on the disk and other features. It is unlikely that it is conspecific with the type specimen. Fell (1961) also suggested that the entire taxon Ophiodaces inanis was possibly only a juvenile stage of Ophiosparte gigas . But Fell’s relatively-large specimen (6.5 mm) has small sub-rounded radial shields, a hardly evident skin layer and conical arm spines. All these features preclude this specimen being identified as Ophiosparte gigas , which has strong, long radial shields, a thick skin layer and apically spatulate arm spines ( Figs 65B–C). However, their features suggest that both the real Ophiodaces inanis as well as Fell’s specimen may actually be related to the family Ophiuridae instead of Ophiacanthidae .

The single specimen of Ophiodaces available for study from the Smithsonian Institution, identified as Ophiodaces cf. inanis (USNM 1106231) did not show any similarity to the description, including photographs of the features of both dorsal and ventral sides ( Koehler 1922b). It possesses tiny, hardly conspicuous radial shields, a very different pattern of the oral frame and adoral shield papillae, long proximally paired tentacle scales, and a different shape of the dorsal and ventral arm plates ( Fig. 42). All these features and the morphology of the arm spine articulations of the present specimen correspond well to the genus Ophiocymbium , but do not meet with any known species from this genus. Therefore, this well-preserved specimen is described in the present study as another new species of the genus, Ophiocymbium antarcticus sp. nov.

Fell (1960) listed Ophiodaces as a synonym of Ophiodictys , and “ inanis Koehler, 1922 ” as the type species of Ophiodictys . These are both errors ( Fell 1961). The genus Ophiodictys , with the type species O. uncinatus Koehler, 1922 is an entirely different taxon, closely related to the genus Ophioplinthaca ( Koehler 1922b; O’Hara & Stöhr 2006).