Kornia sphaeroidalis (Vöhringer, 1960) comb. nov.

Fig. 24; Table 14

Imitoceras sphaeroidale Vöhringer, 1960: 143, pl. 2 fig. 7.

Acutimitoceras sphaeroidale – Korn 1994: 49, text-figs 49e, 55c.

Acutimitoceras (Stockumites) sphaeroidale – Becker 1996: 36.

non Acutimitoceras sphaeroidale – Vöhringer 1960: 143, text-fig. 21. — Korn 1992b: 17, pl. 2 figs 30– 31; 1994: text-figs 50f, 51b, 55d. — Schönlaub et al. 1992: pl. 5 figs 30–31.

Diagnosis

Species of Kornia with a thickly pachyconic, involute conch (ww/dm ~0.80; uw/dm ~0.05) at 24 mm conch diameter. Ornament with widely spaced growth lines with convex course and a shallow ventral sinus.

Material examined

Holotype

GERMANY • Rhenish Mountains, Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 5; Vöhringer Coll.; illustrated by Vöhringer (1960: pl. 2 fig. 7) and Korn (1994: text-fig. 49e); re-illustrated here in Fig. 24; GPIT-PV- 63865.

Additional material

GERMANY • 1 specimen; Rhenish Mountains, Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 5a1; Weyer 1993–1994 Coll.; MB.C. 31068 .

Description

Holotype GPIT-PV-63865 (Fig. 24A) is a thickly pachyconic specimen with 24 mm dm (ww/dm = 0.82). It has a slightly opened umbilicus (uw/dm = 0.06) and a low coiling rate (WER = 1.67). The specimen bears small shell remnants that possess widely spaced, lamellar growth lines; these extend in a low and wide arc across the flanks and form a broad and shallow ventral sinus. Parallel to this extend faint inner shell thickenings (Fig. 24B).

Specimen MB.C.31068 is a rather well-preserved specimen with 13 mm conch diameter (Fig. 24C). It is globular and subinvolute (ww/dm = 0.91; uw/dm = 0.19) with a low coiling rate (WER = 1.56). The whorl profile is C-shaped with rounded umbilical margin and steep, flattened umbilical wall. The shell bears lamellar growth lines directed slightly backwardly from the umbilical margin and forming a shallow, very broad sinus on the venter. There is one shell constriction that extends parallel to the growth lines.

Remarks

Vöhringer (1960) united two species under the name “ Imitoceras sphaeroidale ”. Holotype GPIT- PV-63865 is a nearly globular specimen with 24 mm dm (ww/dm = 0.82), but the illustrated cross section GPIT-PV-63927 (ww/dm = 0.69 at 15 mm dm) and the smaller specimen GPIT-PV-63932 belong to a much more slender form. This is newly described here as Hasselbachia erronea sp. nov. Unfortunately, the morphology of the inner whorls is not known.