DistributionRead full entry
Range DescriptionThis species was historically distributed from New York and Ontario west to South Dakota, Kansas and Oklahoma, and south to Louisiana and Alabama. Large river populations have been largely eliminated in the upper Midwest, but many populations still survive in Mississippi River tributaries. The current distribution of the Round Pigtoe is similar to its historical range. Although large river populations have for the most part disappeared from the upper Midwest, many populations still survive in tributaries of the Mississippi and Ohio rivers. In Canada, the species is only known from southern Ontario (COSEWIC 2004), including the Thames River (Cudmore et al. 2004). Recently this species has been confirmed to be nearly extirpated (last live specimens probably do not represent a viable population) in the main channel of the Detroit River between Lake St. Clair and Lake Erie, Michigan/Ontario, due to Zebra Mussel invasion (Schloesser et al. 2006). Long-standing populations exist in the Poteau River and tributaries, Arkansas and Oklahoma (Vaughn and Spooner 2004). The extent of occurrence has been estimated in excess of 200,000 km2.