Bythinella bicarinata (Des Moulins, 1827)
Two morphs exist: the group “dunkeri”, devoid of spiral keels, restricted to some springs in the French Ardennes, north of Charleville-Mézières, and in the northern part of the Vosges mountains (Katzenberg and Arnsberg areas); and the group “bicarinata” pictured above, which has its settlements between Dordogne and Cantal departments.
Original taxon: Paludina bicarinata. Many synonyms apart from the smooth dunkeri: lalindei (from the type-locality), moulinsii, moutonii, poujolensis and even a tricarinata.
Original taxon: Paludina bicarinata. Many synonyms apart from the smooth dunkeri: lalindei (from the type-locality), moulinsii, moutonii, poujolensis and even a tricarinata.
Specimens from the locus typicus: Source de la Vierge, along the Couze river, near Lalinde, Dordogne, SW. France. Sizes: 2,25-2,3mm. Altitude ≈ 80m.
« …whorls five, the two upper ones small, round, mammillate; the two median ones keeled on their both borders and recessed between, with the keels prominent and blunt; the last one tricarinate. Sutures deeply carved; umbilical slit very narrow… » – C. Des Moulins: “Description d’une nouvelle espèce de Paludine vivante du Périgord”, Bulletin d’Histoire Naturelle de la Société Linnéenne de Bordeaux vol. 2, Bordeaux 1827, p.26.
Same spot. 2,5mm (top) 2,2-2,7-2,35mm (bottom).
Original pictures provided by the Biodiversity Heritage Library.