Pleurotomaria cf. hettangiensis Terquem, 1855

Monari, Stefano, Valentini, Mara & Conti, Maria Alessandra, 2011, Earliest Jurassic patellogastropod, vetigastropod, and neritimorph gastropods from Luxembourg with considerations on the Triassic-Jurassic faunal turnover, Acta Palaeontologica Polonica 56 (2), pp. 349-384 : 365

Pleurotomaria cf. hettangiensis Terquem, 1855

Fig. 10E .

Material.— One specimen: MNHNL BR 432−2, Brouch, Upper Hettangian ( Schlotheimia angulata Zone , Schlotheimia complanata Subzone ).

Dimensions.—See Table 2.

Remarks.—The specimen exhibits strong similarities with the material here assigned to Pleurotomaria hettangiensis Terquem, 1855 . These concern the conical shape of the juvenile shell, the narrow ramp, the elements of the ornament, and the shape and position of the selenizone. It differs from the specimens ascribed here to P. hettangiensis in the narrower spiral angle and the slightly less prominent nodes. These differences are probably due to intraspecific variability. However, there are no intermediate morphs in the present material so that we leave species assignment of this specimen open.

The specimen differs from Pleurotomaria wanderbachi Terquem, 1855 in the shape of the juvenile shell. It is conical with flat whorls almost lacking a ramp, whereas in P. wanderbachi it is definitely gradate.

Figures

Fig. 10. Pleurotomariid gastropods from Brouch (Mersch, Grand−Duchy of Luxembourg), Late Hettangian (Schlotheimia angulata Zone, Schlotheimia complanata Subzone), Early Jurassic. A–D. Pleurotomaria hettangiensis Terquem, 1855. A. MNHNL BR294, dorsal (A1), basal (A2), and apertural (A3) views. B. MNHNL BR676, lateral (B1) and dorsal (B2) views. C. MNHNL BR375−1, dorsal (C1) and apertural (C2) views. D. MNHNL BR443, detail of the ornament (D1), dorsal (D2), and basal (D3) views. E. Pleurotomaria cf. hettangiensis Terquem, 1855, MNHNL BR432−2, dorsal (E1), basal (E2), and apertural (E3) views.