Lapidaster coreytaylori, 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 : 47-49

Lapidaster coreytaylori sp. nov.

urn:lsid:zoobank.org:act:EC3622FF-FE17-43EF-8626-8270BA1F7C38

Fig. 10 : 5-7

Diagnosis

Species of Lapidaster gen. nov. with moderately large LAPs with coarsely meshed stereom in a broad band of the outer surface displaying conspicuously thick trabeculae; ventral portion moderately narrow and strongly protruding ventro-proximalwards; spur on outer proximal edge slender, horizontally elongate and proximally pointed, paralleled by a well-defined spur on the inner distal edge; dorsal part of the ridge on the inner side straight.

Etymology

Species named in honour of Corey Taylor, lead vocalist of the rockgroup Slipknot and Stone Sour, for lending a powerful voice during moments of despair in the course of the present study.

Type material

Holotype GZG.INV.78523 .

Paratypes

GZG.INV.78524, GZG.INV.78525 and GZG.INV.78526.

Type locality and horizon

Carniol, France; Furcatus Zone, middle Aptian, Early Cretaceous.

Additional material

GZG.INV.78527 (51 dissociated LAPs).

Description

Holotype

GZG.INV.78523 is a dissociated medium-sized, proximal LAP; approximately 1.5 times wider than high; distal edge convex; dorsal edge clearly concave as a result of a constriction of the outer surface; ventral quarter of LAP relatively narrow, strongly protruding ventro-proximalwards; ventro-distal tip of LAP very large, tongue shaped and conspicuously protruding; proximal edge separated by sharp kink into dorsal and ventral portion; kink bordered by large, conspicuous, sharply defined, prominent, horizontally strongly elongate and proximally pointed spur composed of dense stereom; coarsely meshed stereom on distal two-thirds of outer surface; trabeculae of outer surface stereom thick but with no tendency to merge into vertical striation; coarsely meshed stereom of outer surface replaced by more finely meshed stereom in proximal third of outer surface. Four ear-shaped spine articulations freestanding on very weakly elevated distal portion of LAP with slight dorsalward increase in size of gaps separating them; second dorsalmost spine articulation slightly larger than remaining three; dorsal and ventral lobes forming continuous volute; all four spine articulations surrounded by irregular, confluent areoles of finely meshed stereom. Ventral edge of LAP with extremely large, deeply concave tentacle notch.

Inner side of LAP with large, sharply defined ridge separated by angular kink into dorsal and ventral portions; dorsal portion oblique, straight, with clearly widened dorsal tip in contact with dorsal edge of LAP; ventral portion straight, forming an almost right angle with dorsal portion and approximately as long as the latter, with thickened, horizontally elongate ventral tip; inner side of ventro-distal tip of LAP thickened with moderately well-defined, round, slightly prominent spur composed of dense stereom. Inner side of large tentacle notch with coarsely meshed and slightly horizontally stretched stereom dorsally bordered by large, irregular perforation.

Paratype supplements and variation

GZG.INV.78524 is a dissociated median LAP, twice wider than high; proximal edge with sharp kink similar to that observed in holotype, bordered by moderately well-defined, elongated and prominent spur; second spur in dorsal half of proximal edge, slightly smaller than ventral spur and protruding, but similarly well defined, prominent and elongate. Outer surface with coarsely meshed stereom, with thick trabeculae showing no tendency to merge into a vertical striation. Three spine articulations separated by equal-sized gaps; middle spine articulation slightly larger than remaining two. Ventral edge of LAP with extremely large, gently concave tentacle notch.

Inner side of LAP with thin, moderately well-defined ridge composed of two portions separated by kink; dorsal portion narrow, with slightly wider dorsal tip; ventral portion of ridge forming acute angle with dorsal one, nearly as long as the latter but wider and less well defined, confluent with ventral edge of LAP.

GZG.INV.78525 is a dissociated distal LAP, approximately 2.5 times wider than high; ventro-distal tip conspicuously protruding; proximal edge concave, with poorly defined, elongate and slightly prominent spur in ventral half; second spur in dorsal half smaller, similarly poorly defined, prominent and slightly protruding. Three spine articulations, ventralmost of which slightly smaller than remaining two. Ventral edge of LAP concave as a result of a clear constriction of the outer surface, and with large, concave tentacle notch.

Inner side of LAP with two moderately well-defined, prominent and slightly elongated spurs on dorsodistal and ventro-distal tips, respectively, dorsal one of which slightly protrudes; ridge on inner side of LAP hardly discernible as a result of insufficient preservation.

GZG.INV.78526 is a dissociated distalmost LAP, rod-like in outline, more than three times wider than high, with concave dorsal and ventral edges. Two small equal-sized spine articulations. No tentacle notch on ventral edge of LAP; tentacle perforation distally bordering ventral spine articulation. Inner side of LAP insufficiently preserved.

Remarks

These LAPs reveal striking similarities to those of Lapidaster mathcore sp. nov. and with the single unnamed LAP from the Kimmeridgian of Germany described above. It differs from the former in displaying a slightly wider ventral portion of the LAPs, coarsely meshed stereom on two-thirds rather than half of the outer surface, a slender, horizontally strongly elongate and proximally pointed spur, and a straight dorsal half of the ridge on the inner side with a more markedly widened dorsal tip. These LAPs, L. mathcore sp. nov. and the unnamed Jurassic specimen form one of the groups of similar species in terms of LAP morphology within Lapidaster gen. nov.. Another example of such a group of morphologically similar LAPs includes L. fasciatus comb. nov., L. mastodon sp. nov. and L. varuna sp. nov. Whether these groups are all assignable to Lapidaster gen. nov. or, in contrast, represent different closely related genera remains to be tested.

Occurrence

Middle Aptian of France.

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.