Lapidaster, 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 : 34

publication ID	https://doi.org/ 10.5852/ejt.2013.48
publication LSID	lsid:zoobank.org:pub:E7080722-E348-448D-96E5-D537F4865BB5
DOI	https://doi.org/10.5281/zenodo.3844279
persistent identifier	https://treatment.plazi.org/id/99789763-6574-8558-D341-27C9FBBA9EE1
treatment provided by	Carolina
scientific name	Lapidaster
status

Treatment

Lapidaster sp. nov. innom. 1

Fig. 8 View Fig : 1

p.p. Ophiacantha ? toarcensis – Hess 1962: 649 (Schicht C) (original specimen incorrectly assigned to Ophiacantha ? toarcensis Hess, 1962 ).

Material examined

NHMB M 11208 (dissociated LAP) from the late Toarcian of Seewen, Switzerland, the original material of Hess (1962).

Description

Single dissociated, median to proximal LAP, slightly wider than high, dorsal edge nearly straight, distal edge strongly convex; ventral fifth protruding ventro-proximalwards; ventro-distal tip of LAP large, rounded, protruding; proximal edge concave, with large, strongly protruding, sharply defined, horizontally elongate, lens-shaped, prominent spur in the middle, and with second horizontally elongated, lens-shaped but slightly smaller, less well-defined, less prominent and protruding spur close to ventroproximal tip of LAP; outer surface with very slight constriction, and with coarsely meshed stereom; trabeculae of outer surface stereom showing weak tendency to merge into short, irregular vertical stripes close to row of spine articulations. Four small spine articulations, ventralmost slightly smaller than other three; dorsal and ventral lobes separated by small, round knob; strong dorsal increase in size of gaps separating spine articulations; two ventral spine articulations separated from coarsely meshed outer surface stereom by faint, irregular, confluent areoles; two dorsal spine articulations embedded in outer surface stereom. Ventral edge of LAP with large, moderately deep tentacle notch.

Inner side of LAP with sharply defined, dorsal portion of which straight to slightly bent, not widened dorsally and not approaching ventral or dorsal edges of LAP; ventral portion of LAP separated from dorsal one by rounded kink, very short and sharply defined, not merging with ventral part of LAP; inner distal edge with two large, well-defined, horizontally elongate, prominent spurs composed of dense stereom, ventral one of which slightly protruding. Inner side of tentacle notch moderately large and with coarsely meshed, slightly horizontally stretched stereom. No perforations discernible on inner side.

Remarks

Among the original material of Ophiacantha ? toarcensis Hess, 1962 from the Toarcian of Switzerland, here reassigned to Dermocoma Hess, 1964 (see below), is a single LAP which obviously does not belong to that species. A detailed re-examination of that plate has revealed that it is a species of Lapidaster gen. nov., on account of its Ophiologimus -like morphology and the presence of spurs on the outer proximal and inner distal edges. The unusually small spine articulations composed of separated dorsal and ventral lobes, as well as the presence of a second, strongly developed spur in the centre of the outer proximal and inner distal edges sets the LAP in question quite apart from other LAP types assigned to Lapidaster gen. nov. It unquestionably represents a distinct, undescribed species. Unfortunately, only a single LAP is currently known, which precludes the formal description of a new species.