Bythinella

Bythinella is a genus of very small freshwater snails, an aquatic gastropod mollusk in the family Amnicolidae (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). These gonochoristic snails are small animals, with a shell length of about 2–4 mm. Amnicola is a close relative, containing North American snails with essentially similar appearance and ecology. The scientific name means 'small Bithynia'; the latter snail genus is somewhat similar at a casual glance (though much larger) but not at all closely related among the Rissooidea. The present genus occurs in springs, and sometimes caves or groundwater, from Catalonia across central Europe to the Aegean Region of Turkey. In and around France a particularly high diversity of these snails is found. Due to the limited range and special and easily destroyed habitat, these snails are liable to become endangered species. More than 80 species and subspecies are recognized at present. However, it is not at all clear that all of those recognized as good species are actually that distinct, and some in fact seem to be local morphs instead of valid taxa. Some undescribed species are also known to exist.