Dermacantha Thuy 2013, gen. nov.

Genus Dermacantha gen. nov.

urn:lsid:zoobank.org:act: D73D5436-6A0A-43C1-8298-C5C4BE5D5CA3

Type species

Dermacantha leonorae sp. nov., by present designation.

Other species included

Dermacantha pattyana sp. nov., Ophiocten? seeweni Kutscher & Hary, 1991 and Dermacantha carli sp. nov.

Diagnosis

Ophiacanthid with small to moderately large LAPs; small height/width ratio, even in proximal LAPs; relatively few (up to five) small spine articulations in notches of slightly elevated distal portion of LAP; ventral and dorsal lobes of spine articulations proximally separated by small knob; ventral portion of LAP generally strongly protruding ventro-proximalwards; up to two poorly to well-defined spurs on outer proximal and inner distal edges; inner side of LAPs with simple, slender ridge devoid of sharp kinks or strongly thickened parts; tentacle notch small.

Etymology

Name composed of derma, Greek for “skin”, and Acantha, a nymph in Greek mythology whose name literally translates as “thorny”, in reference to the striking similarities in LAP morphology shared with Dermocoma.

Remarks

The ophiacanthid fossil record includes a number of dissociated LAP types which, at first sight, seem compatible with the LAP morphological diagnosis of Dermocoma, in particular with respect to the strongly protruding ventral portion of the LAPs, the position of the spine articulations, the presence of spurs on the outer proximal and inner distal edges and the shape of the ridge on the inner side. The spine articulation morphology, however, differs markedly. In fact, while the LAPs of Dermocoma display spine articulations with a continuous volute, those of the LAP type in question have the ventral and dorsal lobes proximally separated by one or several small knobs. This significant difference is generally combined with a smaller height/width ratio, even in proximal LAPs, and with smaller spine articulations than in Dermocoma. Since these differences co-occur consistently, Dermacantha gen. nov. is introduced here to accommodate the Dermocoma -like LAP types with small spine articulations displaying a discontinuous volute. The striking similarities in LAP morphology, however, strongly suggest that Dermocoma and Dermacantha gen. nov. share close phylogenetic ties, as suggested by the name of the new genus.

Superficial similarities are shared with the LAPs of Lapidaster gen. nov. with respect to the weakly elevated distal portion of the LAPs and the spurs on the outer proximal and inner distal edges. In Lapidaster gen. nov., however, the spine articulations are never sunken into notches of the distal LAP portion, and the tentacle notch generally is much larger.