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pressed river mussel
Relationsship and features of typical shells (taxonomy)
The sub-oval shell reaches a total length of 6 - 8,5 cm and is markedly compressed from both sides. The colour of the shell is green olive - brown. The umbones are near to the anterior (front) end and the upper and lower margins of the shell are not parallel, but diverging from the anterior to the posterior. The umbonal rugae consist of 3 - 5 irregular ridges that are crosswise to the growth lines. There are no hinge-teeth.
The species is mostly an inhabitant of lakes and slow flowing parts of rivers in Sweden. It is mainly found on sandy bottom in waters rich in nutrient. The populations are often small and isolated. Red listed as a "near threatened" (NT) species in Sweden.
Rare in Sweden. Scattered appearance ranging from Scania in the very south up to the middle part of the Country. Not present north of "Limes Norrlandicus".
Photo: Håkan Holmberg Scientific basis: Ted von Proschwitz