About Pisidium amnicum (O.F.Müller, 1774)
Pisidium amnicum (O.F.Müller, 1774) reaches an average length of 9 mm, with a total length range of 7–11 mm. While small, this species is considerably larger than most other species in the Pisidium genus. It has a fairly thick, solid, glossy shell that is marked with concentric ridges. The shell is shaped like a triangle-oval. Its broad umbos are not prominent, and they are often covered with a dull ferruginous deposit. Shell color ranges from grey-white to brown, and often carries a greenish cast. The native distribution of this species is the Palearctic region. It has been introduced to northeastern North America. Within its range, it holds specific conservation statuses: it is listed as endangered (EN) in the Czech Republic, endangered (EN) in Bohemia, and critically endangered in Moravia; it is also endangered in Slovakia, and classified as highly endangered (Stark gefährdet) in Germany. It is found across the Nordic countries of Denmark, Finland, Iceland, Norway, and Sweden, and is not present in the Faroe Islands. It also occurs in Great Britain and Ireland. In Europe, this species requires clean water and high calcium levels to survive.
