Ophiogaleus Thuy 2013
Creators: name: Thuy, Ben
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Ophiuroidea
Ophiurida
Ophiacanthidae
Ophiogaleus

description: Ophiogaleus sp. nov. innom. 1
Fig. 19: 10-12
Material examined
NHMW 2012/0137/0017, NHMW 2012/0137/0018, NHMW 2012/0137/0019 and NHMW 2012/0137/0020 (12 dissociated LAPs) from the late Sinemurian to early Pliensbachian of the Glasenbach Gorge, Austria.
Description
Relatively large, dissociated proximal to median, fragmentary LAPs; originally much higher than wide; dorsal edge not preserved; well-developed constriction; distal edge convex; proximal edge irregularly undulose; at least one large, moderately well-defined, prominent and slightly protruding, oval spur in the ventral half of the proximal edge, composed of more densely meshed stereom; outer surface with moderately finely meshed stereom, replaced by more finely meshed stereom in a relatively broad band paralleling proximal edge of LAP; trabecular intersections of outer surface stereom not thickened or developed into granules. At least six large, ear-shaped spine articulations freestanding on strongly elevated distal portion of LAP; dorsal and ventral lobes of spine articulations merged into continuous, conspicuously oblique volute; spine articulations proximally sharply bordered by well-defined but weakly prominent, near-straight ridge; very weak dorsalward increase in size of spine articulations and of gaps separating them; relatively narrow gap between spine articulations and distal edge of LAP; row of spine articulations originally most probably slightly protruding ventralwards.
Inner side of LAPs with large, sharply defined and prominent ridge; ventral part long, relatively narrow, strongly bent, ventral tip slightly pointed, sharply separated from ventral portion of LAP; dorsal part of ridge fragmentary in all available LAPs, slightly widened, small, vertically elongate, exact outline not unambiguously determinable; inner side of distal edge of LAP with one to two small, moderately well to poorly defined, horizontally elongate and slightly prominent spurs; inner side of tentacle notch relatively large, well defined laterally. No perforations or furrow discernible.
Remarks
The limited amount of material available and its fragmentary condition make a sound systematic assessment difficult. While assignment to the Ophiacanthidae is unquestionable on account of the spine articulation structure and the morphology of the inner side, affinities within this family are more problematic. Greatest similarities are shared with the LAPs of Ophiogaleus gen. nov. on account of the number, position and shape of the spine articulations and the number and position of spurs on the outer proximal and inner distal edges. The shape of the ridge on the inner side, however, is rather atypical for Ophiogaleus gen. nov. with respect to the narrow dorsal part of the ridge. In the light of the similarly atypical ridge in Ophiogaleus dorecki (Hess, 1962) comb. nov. (see below), known from more complete material, assignment to Ophiogaleus gen. nov. seems justified after all, especially considering the possibility that the above-described specimens and the slightly younger O. dorecki are two stratigraphically closely spaced representatives of the same lineage. Within Ophiogaleus gen. nov., the LAPs described above are unique in displaying oblique spine articulations. The fragmentary nature of the record, however, precludes a formal description of this species in the present study.
description: Published as part of Thuy, Ben, 2013, Temporary expansion to shelf depths rather than an onshore-offshore trend: the shallow-water rise and demise of the modern deep-sea brittle star family Ophiacanthidae (Echinodermata: Ophiuroidea), pp. 1-242 in European Journal of Taxonomy 48 on pages 109-110, DOI: 10.5852/ejt.2013.48, http://zenodo.org/record/3822836