Europacantha, Thuy, 2013

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), European Journal of Taxonomy 48, pp. 1-242 : 96

Genus Europacantha gen. nov.

urn:lsid:zoobank.org:act:511AAE08-FCA9-4DA9-AFC4-6B2A2C39B2DB

Type and sole known species

Europacantha paciphila sp. nov.

Diagnosis

Ophiacanthid with relatively small, stout, trapezoid LAPs devoid of conspicuous outer surface ornament; small, inconspicuous, very weakly protruding spur on outer proximal edge; up to six large, ear-shaped spine articulations on strongly elevated distal portion of LAP, not bordered proximally by a ridge-like structure; relatively broad, gently proximally bent ridge on inner side with widened dorsal tip displaying a ventrally projecting extension; tentacle notch small, invisible in external view.

Etymology

Name composed of Europa , a Phoenician princess whose name is commonly translated into “perspicacious”, honouring the idea of a united Europe, and Acantha , a Greek nymph whose name literally translates into “thorny”; gender feminine.

Remarks

The oldest known ophiacanthid record is here described in the form of rare dissociated LAPs from the Anisian (early Middle Triassic) of Hungary. The LAPs in question are unambiguously assignable to the Ophiacanthidae on account of the large, ear-shaped spine articulations with a typical sigmoidal fold, combined with several small perforations in a shallow vertical furrow on the inner side. Astonishingly, these Anisian LAPs display small tentacle notches, almost certainly reflecting originally small tentacle pores as defined by Thuy et al. (2012), which places them in the more derived small-pored ophiacanthids rather than the basal large-pored ones.

Indeed, greatest similarities in LAP morphology are shared with the small-pored Ophiacantha , on account of the number, size and position of the spine articulations, the absence of more than a single spur on the outer proximal edge, and the shape of the ridge on the inner side, as well as with Inexpectacantha Thuy, 2011 on account of the stout, trapezoid aspect, the proximally non-bordered spine articulations and the lack of a conspicuous outer surface ornament. Yet, in the LAPs of Ophiacantha , the spine articulations are proximally sharply bordered by a ridge or the distalmost lamella of the outer surface striation, while in Inexpectacantha the ridge on the inner side of the LAPs lacks a ventrally projecting extension, and the spine articulations are more oblique, displaying a coarsely corrugated ventral lobe. On account of these incompatibilities, Europacantha gen. nov. is thus introduced here to accommodate the Anisian LAPs.