Lapidaster lukenederi, 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 : 46-47

Lapidaster lukenederi sp. nov.

urn:lsid:zoobank.org:act:7E64C5B3-CAFF-4342-AD67-DDB05F3050EB

Fig. 10 : 1-3

Diagnosis

Species of Lapidaster gen. nov. with small LAPs displaying a low height/width ratio and a welldeveloped constriction; ventral portion of LAP not thickened; spur on the outer proximal and inner distal edges very poorly defined; dorsal part of ridge on inner side not widened.

Etymology

Named in honour of Alexander Lukeneder (Naturhistorisches Museum Wien, Vienna), who collected and generously provided the residues yielding the type material of the new species.

Type material

Holotype

NHMW 2012/0138/0001 .

Paratypes

NHMW 2012/0138/0002 and NHMW 2012/0138/0003.

Type locality and horizon

KB1-A section of Lukeneder (2004) in the Ternberg Nappe, Austria; Verrucosum Zone, late Valanginian, Early Cretaceous.

Additional material

NHMW 2012/0138/0004 (88 dissociated LAPs).

Description

Holotype

NHMW 2012/0138/0001 is a dissociated, small, proximal to median LAP, approximately 1.5 times wider than high, with gently convex distal edge; dorsal edge clearly concave, indicating a slight constriction of the outer surface; ventral fifth of LAP protruding ventro-proximalwards; ventro-distal tip of LAP not conspicuously large, slightly protruding ventro-distalwards; proximal edge of LAP angular, with small very faint, hardly discernible, spur-like structure near ventro-proximal tip of LAP; outer surface with coarsely meshed stereom; trabeculae of outer surface stereom showing no tendency to merge into vertical striation. Four relatively small spine articulations, ventralmost slightly smaller than remaining three; very small dorsalward increase in size of gaps separating spine articulations; dorsal and ventral lobes composing volute connected by very short, markedly narrow ridge proximally; dorsalmost spine articulation pointing dorsalwards; all spine articulations embedded in outer surface stereom. Ventral edge of LAP with moderately large, gently concave tentacle notch.

Inner side of LAP with relatively narrow, well-defined ridge, dorsal portion of which nearly straight, widest in middle part, with narrow tip not reaching dorsal and distal edges of LAP; ventral portion of ridge separated from dorsal one by kink, shorter, wider, less well defined but not confluent with ventral part of LAP; ventral part of LAP not thickened; ventro-distal tip of LAP with barely discernible spur composed of slightly denser stereom; inner side of tentacle notch with coarsely meshed stereom, hardly stretched horizontally. No perforations visible on inner side.

Paratype supplements and variation

NHMW 2012/0138/0002 is a dissociated median LAP, approximately twice wider than high; ventrodistal tip of LAP slightly larger than in holotype; dorsal edge strongly concave, indicating well-developed constriction; proximal edge gently concave with small, very poorly defined, barely visible spur close to ventro-proximal tip of LAP; outer surface with coarsely meshed stereom with very weak tendency of trabeculae to merge into irregular vertical striation. Three equal-sized spine articulations, separated by equal-sized gaps.

Inner side of LAP generally well in agreement with that of holotype; dorsal portion of ridge straight, slightly widened dorsally; ventral portion of ridge wider, very short, poorly defined but not confluent with ventral part of LAP; no spur discernible on inner side of ventro-distal tip of LAP.

NHMW 2012/0138/0003 is a dissociated distal plate, more than twice wider than high; both dorsal and ventral edges concave as a result of the constriction; no spur discernible on proximal edge of LAP. Three equal-sized spine articulations near distal edge of LAP, separated by equal-sized gaps. Ventral edge of LAP with large, gently concave tentacle notch.

Inner side with moderately well-defined ridge, oblique and slightly bent, relatively wide, short; no kink separating ridge into dorsal and ventral portions; ventral tip of ridge widest, best defined; no spur discernible on inner side of ventro-distal tip of LAP.

Remarks

These LAPs share greatest similarities with those of Lapidaster etteri sp. nov., especially with regard to the constriction and the height/width ratio of the proximal LAPs. In the latter, however, the the ventral part is more strongly thickened, the dorsal tip of the ridge on the inner side is widened, and the spur on the outer proximal and inner distal edges is slightly better defined.

Occurrence

Late Valanginian of Austria.

Figures

Fig. 10. Fossil lateral arm plates (LAPs) of ophiacanthid brittle stars in external (a) and internal (b) views. 1-3. Lapidaster lukenederi gen. et sp. nov. from the late Valanginian (Early Cretaceous) of the Ternberg Nappe, Austria. 1. NHMW 2012/0138/0001 (holotype), proximal LAP. 2. NHMW 2012/0138/0002 (paratype), median LAP. 3. NHMW 2012/0138/0003 (paratype), distal LAP. 4. Lapidaster sp. nov. innom. 2 from the early Kimmeridgian (Late Jurassic) of Geisingen, Germany; GZG.INV.78522, proximal to median LAP. 5-7. Lapidaster coreytaylori gen. et sp. nov. from the middle Aptian (Early Cretaceous) of Carniol, France. 5. GZG.INV.78523 (holotype), proximal LAP. 6. GZG.INV.78524 (paratype), median LAP. 7. GZG.INV.78525 (paratype), distal LAP. 8-10. Lapidaster mathcore gen. et sp. nov. from the middle Albian (Early Cretaceous) of Folkestone, Great Britain. 8. GZG.INV.78528 (holotype), proximal LAP. 9. GZG.INV.78529 (paratype), median LAP. 10. GZG.INV.78530 (paratype), distal LAP. One common scale bar per species is given.