Pisidium pseudosphaeriumPisidium pseudosphaerium is a species of freshwater bivalve from family Sphaeriidae.DescriptionThe 2.5-3.2mm shell is a flattened, regular, slightly angulated oval shape with low central umbos. The surface is silky with very fine concentric striations. In colour it is straw-yellow with scattered red-brown deposits.DistributionIts native distribution is central European and western European. Czech Republic - in Bohemia, in Moravia, critically endangered Germany - critically endangered Nordic countries: Denmark, Finland, Norway and Sweden Great Britain and Ireland