Sphaerium nucleus
Sphaerium nucleus is a freshwater bivalve of the family Sphaeriidae. It has been often confused with Sphaerium corneum and is consequently quite poorly known.
Description
Sphaerium nucleus is a very small bivalve which may grow up to 8mm in width and length. It differs from Sphaerium corneum only in details. Like almost all bivalves, it is a filter-feeder.Taxonomy
Sphaerium nucleus was described by Studer 1820, who placed it in the genus Cyclas. It was later thought to be a subspecies of Sphaerium corneum. Subsequently it was raised to a full species again as Sphaerium nucleus due to its having a different form of kidney, and the shell having a broad hinge plate, dense porosity and more tumid shells with broad umbones. Unlike S. corneum it has a preference for temporary habitats.Distribution
S. nucleus occurs widely in Europe, from Spain to Ukraine. It appears to be absent from Russia.- Austria
- Britain and Ireland
- Czech Republic – in Bohemia, in Moravia
- Germany
- Kyrgyzstan
- Slovakia
- Ukraine