Ophioleviathan watsoni, 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 : 194-196

Ophioleviathan watsoni sp. nov.

urn:lsid:zoobank.org:act:657FB229-47E4-48F1-8913-9A83DD42AB05

Fig. 34 : 1-4

Sigsbeia? lunaris – Hess 2006: 66, pl. 29 figs 8-9 [material incorrectly assigned to Sigsbeia? lunaris ( Hess, 1962) ].

Diagnosis

As for genus.

Etymology

Species named in honour of Paul Watson, founder of the Sea Shepherd Conservation Society, in admiring recognition of his relentless commitment to the protection of marine wildlife.

Type material

Holotype

NHMW 2012/0137/0024 .

Paratypes

NHMW 2012/0137/0025, NHMW 2012/0137/0026 and NHMW 2012/0137/0027.

Type locality and horizon

Glasenbach Gorge, Austria; Hauptknollenbrekzie, late Sinemurian to early Pliensbachian, Early Jurassic.

Additional material

NHMW 2012/0137/0028 (21 dissociated LAPs) from the late Sinemurian to early Pliensbachian of the Glasenbach Gorge, Austria; original material of Hess (2006) from the late Pliensbachian of Arzo, Switzerland.

Description

Holotype

NHMW 2012/0137/0024 is a very large, dissociated proximal LAP; nearly 2.5 times higher than wide; of massive and extremely thick aspect; dorsal edge convex, oblique; distal edge evenly convex; proximal edge irregularly concave, devoid of spurs; very narrow, slightly depressed area along the central part of the proximal ridge; outer surface with finely meshed stereom, devoid of conspicuous ornament elements. Seven large, ear-shaped spine articulations in deep notches of strongly bulging distal portion of LAP; spine articulations vertical or even slightly overturned, composed of distal and proximal rather than dorsal and ventral lobes; proximal lobe relatively slender, rugged and confluent with stereom of notch; dorsally merged with much larger and thicker, much more strongly prominent distal lobe into continuous, vertically elongate volute; middle spine articulations largest, with dorsalward and ventralward decrease in size; spine articulations nearly equi distant and proximally sharply bordered by edge of notches; gap between spine articulations and distal edge of LAP almost as wide as one spine articulation. Ventral edge of LAP oblique, very weakly convex.

Inner side of LAP with extremely large, broad, well-defined, prominent, slightly dorso-proximalwards bent, tongue-shaped ridge devoid of kinks; ventral tip of ridge not merged with ventral tip of LAP; dorsal part of ridge wider than ventral part; no spurs on inner side of distal edge of LAP; inner side of tentacle notch extremely small, very poorly defined, almost indiscernible; dorsal and ventral tips of LAP protruding towards midline of arm. Shallow, poorly defined, vertical furrow dorsally bordering tentacle notch; no perforations discernible.

Paratype supplements and variation

NHMW 2012/0137/0025 is a dissociated proximal LAP; approximately twice higher than wide; very well in agreement with holotype. Six spine articulations similar to those observed on holotype.

Ridge on inner side of LAP slightly better preserved than in holotype, very large, extremely wide, with much more slender ventral part not merged with ventral portion of LAP; inner side of tentacle notch very small, poorly defined. Shallow, moderately well-defined vertical furrow dorsally bordering tentacle notch, with two to three minute, irregularly spaced perforations.

NHMW 2012/0137/0026 is a dissociated median LAP; slightly higher than wide; dorsal edge oblique, straight; slightly depressed band along central part of proximal edge very weakly developed, almost indiscernible. Five spine articulations similar to those observed on holotype, less sharply defined proximally. Ventral edge of LAP straight, oblique.

Ridge on inner side of LAP similar to that of holotype but shorter, broader; inner side of tentacle notch as small and poorly defined as in holotype, oblique; dorsal and ventral tips of LAP protruding towards midline of arm. No perforations or furrow discernible.

NHMW 2012/0137/0027 is a dissociated distal LAP; nearly as high as wide, of rounded aspect; depressed area along the middle part of the proximal edge absent. Five large, spine articulations similar to those observed on holotype; distal lobe even larger, thicker, more prominent than in holotype; gap between spine articulations and distal edge of LAP narrower.

Ridge on inner side of LAP similar to that of holotype but slightly smaller, narrower and shorter. No perforations or furrow discernible.

Remarks

This LAP type is the only one currently assignable to Ophioleviathan gen. nov. Its systematic placement and affinities with other LAP types are discussed above.

Occurrence

Late Sinemurian to early Pliensbachian of Austria, late Pliensbachian of Switzerland.

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.