Swan mussel
The swan mussel, Anodonta cygnea, is a large species of freshwater mussel, an aquatic bivalve mollusc in the family Unionidae, the river mussels.
Because of its morphological variability and its wide range of distribution, there are over 500 synonyms for this species.
Shell description
The shell is thin but large (approximately 10 to 20 cm) and rather flat, even at the umbo. The shell color is often pale greenish or brownish.For differences from Anodonta anatina see Animalbase below (external links).
Distribution
Its native distribution is European-Siberian. The geographical distribution of this species is from the British Isles east to Siberia, and south into northern Africa.
Croatia
Czech Republic - in Bohemia, in Moravia, vulnerable (VU); Czech code, Decree for implementation, No. 395/1992 Sb. (and No. 175/2006 Sb.) - Highly threatened species.
Germany