Potamilus ohiensis (Rafinesque, 1820)
Potamilus ohiensis, INHS 2197. Kankakee River, Will County, Illinois.
Other common names Papershell, fragile heelsplitter.
Key characters Thin, shiny, elongate and compressed shell, tan or olive green to dark brown, with pink to purple nacre.
Similar species Fragile papershell, pink heelsplitter.
Description Shell elongate, thin, fragile, and compressed. Anterior and posterior ends rounded. A large wing present behind the umbo, with a smaller wing in front, but often missing in older shells. Umbos flattened and not elevated above the hinge line. Beak sculpture of three or four small, thickened ridges. Shell very shiny, rayless, tan or olive green to dark brown (dark brown particularly in older shells). Length to 7 inches (17.8 cm).
Pseudocardinal teeth thin, elongate, and slightly roughened; one in the left valve, two in the right. Lateral teeth long, thin, elevated, and straight or slightly curved. Beak cavity shallow. Nacre typically light purple, occasionally pink, and highly iridescent.
Habitat Medium to large rivers in silt, mud, or sand.
Status Widespread and locally common.