Pachycrommium scalariformis (Deshayes, 1825)

Caze, Bruno, Merle, Didier, Meur, Mathieu Le, Pacaud, Jean-Michel, Ledon, Daniel & Martin, Jean-Paul Saint, 2011, Taxonomic implications of the residual colour patterns of ampullinid gastropods and their contribution to the discrimination from naticids, Acta Palaeontologica Polonica 56 (2), pp. 329-347 : 343

Pachycrommium scalariformis (Deshayes, 1825)

Fig. 8E, F .

Stratigraphic and geographic range.—Middle Eocene, Lutetian (PB, HB).

Colour pattern description.—The colour pattern consists of a dark and homogeneous background and broad axial slightly fluorescent stripes ( Fig. 8E, F ). These stripes appear straight on the spire but present saw−tooth edges. They actually form zigzags spreading over the whole height of the whorl. Their width is not constant ( Fig. 8F ).

Figures

Fig. 8. Species of the genus Pachycrommium Woodring, 1928, under UV light. A. Pachycrommium suessoniensis (d’Orbigny, 1850), MNHN A30881 (Pacaud coll.), Celles−sur−Aisne, Aisne, France, Ypresian (Cuisian), in ventral (A1) and apical (A2) views. B. Pachycrommium suessoniensis (d’Orbigny, 1850), MNHN A30882 (Pacaud coll.), Celles−sur−Aisne, in apical (B1) and dorsal (B2) views. C. Pachycrommium productum (Deshayes, 1864), MNHN A30945 (Pacaud coll.), Chaussy, Val d’Oise, France, Lutetian, in dorsal view. D. Pachycrommium sp., MNHN A30482 (Pacaud coll.), Monampteuil, Aisne, France, Ypresian (Cuisian), in ventral (D1) and dorsal (D2) views. E. Pachycrommium scalariformis (Deshayes, 1825), MNHN A30401 (Ledon leg.), Fontenay−en−Vexin, Lutetian, in apical view. F. Pachycrommium scalariformis (Deshayes, 1825), MNHN A30402 (Ledon leg.), Fontenay−en−Vexin, view of a shell fragment. Scale bars 10 mm. Photographs by C. Lemzaouda and P. Loubry (MNHN).