Manfredura curvata ( Kutscher & Jagt, 2000 ) 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 : 197-198

Manfredura curvata ( Kutscher & Jagt, 2000) comb. nov.

Fig. 34 : 5-7

Ophiomyxa? curvata Kutscher & Jagt, 2000: 53 , pl. 31 figs 4-7.

non Ophiomyxa? cf. curvata – Štorc & Žítt 2008: 125, fig. 4G-K.

Diagnosis

As for genus.

Material examined

GZG.INV.78759, GZG.INV.78760, GZG.INV.78761 and 416 dissociated LAPs in the Manfred Kutscher Collection, Sassnitz, Germany, the type material of Kutscher & Jagt (2000); GZG.INV.78762 (3 dissociated LAPs) from the early Maastrichtian of Lägerdorf-Kronsmoor, Germany.

Description

Large dissociated LAPs, of massive, thick and strongly curved aspect; proximal LAPs almost three times higher than wide, distal ones slightly higher than wide; dorsal edge straight, oblique (proximal LAPs) to strongly concave as a result of a constriction (distal LAPs); distal edge convex; proximal edge irregularly concave, with a weakly protruding, non-prominent central part; proximal to median LAPs with strongly depressed, distally well-defined band as wide as one-quarter of the total LAP width along the proximal edge except for its ventralmost part; much less well-defined, depressed band along central part of proximal edge in distal LAPs; outer surface with finely meshed stereom, devoid of conspicuous ornament elements. Ten (proximal LAPs) to seven (distal LAPs) large, ear-shaped spine articulations freestanding on strongly elevated distal portion of LAP; dorsal lobe of spine articulations larger and thicker than ventral one, merged with the latter into continuous volute; weak dorsalward incrase in size of spine articulations and of gaps separating them; gap between spine articulations and distal edge of LAP relatively narrow; spine articulations not sharply bordered proximally by ridge-like structure. Ventral edge of LAP irregularly concave; tentacle notch invisible in external view.

Inner side of LAP with very small, sharply defined, prominent, slender, dorso-proximalwards bent, tongue-shaped ridge devoid of kinks and strongly widened parts; small, well-defined, prominent, vertically elongate knobs close to the dorso-proximal and ventro-proximal tips of the proximal and median LAPs; ridge on inner side of distal LAPs larger, no knobs; no spurs on inner side of distal edge of LAPs; inner side of tentacle notch very small, shallow and poorly defined, almost indiscernible. Few, minute, inconspicuous perforations in vertical row distally bordering ventral tip of ridge.

Remarks

The LAPs of Manfredura curvata comb. nov. are highly diagnostic and cannot be confused with any other type of LAP, except for the material from the Turonian of the Czech Republic described and illustrated by Štorc & Žítt (2008), who tentatively assigned this to Ophiomyxa ? curvata . The specimens in question indeed display a striking similarity to the LAPs of M. curvata comb. nov. with respect to general shape, height/width ratio, shape and position of the spine articulations and size of the tentacle notch. While it seems likely that the LAPs in question are assignable to Manfredura gen. nov., they clearly belong to a different, still undescribed species. In fact, the Turonian LAPs display spine articulations with a much stronger dorsalward increase in size, a less well-developed depressed band along the proximal edge, a much more slender ridge on the inner side, and no knobs on the inner side of the dorso- and ventroproximal tips of the LAP.

Occurrence

Early Maastrichtian of Germany.

Figures

Fig. 34. Lateral arm plates (LAPs) of fossil and Recent ophiacanthid brittle stars in external (a) and internal (b) views. 1-4. Ophioleviathan watsoni gen. et sp. nov. from the late Sinemurian to early Pliensbachian (Early Jurassic) of the Glasenbach Gorge, Austria. 1. NHMW 2012/0137/0024 (holotype), proximal LAP. 2. NHMW 2012/0137/0025 (paratype), proximal LAP. 3. NHMW 2012/0137/0026 (paratype), median LAP. 4. NHMW 2012/0137/0027 (paratype), distal LAP. 5-7. Manfredura curvata (Kutscher & Jagt, 2000) comb. nov. from the early Maastrichtian (Late Cretaceous) of Rügen, Germany. 5. GZG.INV.78759, proximal LAP. 6. GZG.INV.78760, median LAP. 7. GZG.INV.78761, distal LAP. 8-9. Ophiomitra valida Lyman, 1869, Recent. 8. Proximal LAP. 9. Median LAP. One common scale bar per species.