Weyerella lenis, Korn & Weyer, 2023

Korn, Dieter & Weyer, Dieter, 2023, The ammonoids from the Gattendorfia Limestone of Oberrödinghausen (Early Carboniferous; Rhenish Mountains, Germany), European Journal of Taxonomy 882, pp. 1-230 : 159-160

Weyerella lenis sp. nov.

urn:lsid:zoobank.org:act:283ADBFB-4091-447B-96E2-859E01547509

Fig. 96 ; Tables 93–94

Diagnosis

Species of Weyerella with a conch reaching 25 mm diameter. Conch at 15 mm dm extremely discoidal, subevolute (ww/dm ~0.32; uw/dm ~0.35). Whorl profile at 15 mm dm weakly compressed (ww/wh ~0.85); coiling rate very low (WER ~1.45). Venter continuously rounded, umbilical margin narrowly rounded. Shell nearly smooth; without constrictions on the shell surface.

Etymology

From the Latin ‘ lenis ’ = ‘gentle’, referring to the very weak ornament.

Material examined

Holotype

GERMANY • Rhenish Mountains , Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 2a; Weyer 1993–1994 Coll.; illustrated in Fig. 96A ; MB.C.31192.

Paratype

GERMANY • 1 specimen; Rhenish Mountains , Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 2; Vöhringer Coll.; GPIT-PV-63929 .

Description

Holotype MB.C.31192 is an incomplete specimen with approximately 15 mm conch diameter ( Fig. 96A ). It is thinly discoidal and subevolute (ww/dm = 0.34; uw/dm = 0.36); the whorl profile is weakly compressed (ww/dm = 0.91) with slightly flattened, convergent flanks and a continuously rounded venter. The coiling rate is low (WER = 1.44). The shell surface appears to be completely smooth with the exception of a few barely discernible radial folds that extend backwards on the flank.

Paratype GPIT-PV-63929 had already been sectioned by Vöhringer, but not illustrated. It allows the study of all whorls up to a conch diameter of 9 mm ( Fig. 96B ). The whorl profile is kidney-shaped up to 5 mm conch diameter, thereafter it becomes C-shaped with increasing enclosure of the preceding whorl. The aperture is low in all stages; the coiling rate is always close to 1.50.

Remarks

Weyerella lenis sp. nov. differs from all the other species of the genus Weyerella in the combination of the very slender conch, the low coiling rate (WER ~1.50) and the smooth shell.

Figures

Fig. 96. Weyerella lenis sp. nov. from the Oberrödinghausen railway cutting. A. Holotype MB.C.31192 (Weyer 1993–1994 Coll.) from bed 2a. B. Cross section of paratype GPIT-PV-63929 (Vöhringer Coll.) from bed 2. C–E. Ontogenetic development of the conch width index (ww/dm), umbilical width index (uw/dm), whorl width index (ww/wh) and whorl expansion rate (WER) of the holotype and the paratype. Scale bar units = 1 mm.