Bythiospeum bressanum Bernasconi, 1985

Known distribution: Jura, Ain, Doubs, Isère. Stygobiont in karstic aquifers and water tables.
A specimen from the type-locality: karst spring in the south-east of Frétigny, Valzin-en-Petite-Montagne, Doubs, E. France. Altitude ≈ 465m (480m in Bernasconi). 2,9mm.
Same spot. 2,6mm.
The morphology does not provide significant features: « …umbilical slit narrow; spire made up of 6 rounded whorls, sutures deep; summit obtuse; aperture suboval slightly slanted, not very patulescent at the base, external margin projected forward; test horny showing only growth striations. » – R. Bernasconi: “Bythiospeum (Mollusca Gasteropoda Hydrobidae) de France, nouveaux ou faisant l’objet d’une révision”, Revue Suisse de Zoologie vol. 92(2), Genève 1985, p.341. – Same spot: variations of shape. 2,5-2,8mm.

 
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