Cyprogenia stegaria

Also known as Fanshell

The Fanshell (Cyprogenia stegaria) is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels. Historically widespread throughout the Ohio, Cumberland, and Tennessee river systems, this species, native to the United States, now occurs in only a few isolated populations and faces a severe threat to its continued existence. It is federally listed as an Endangered species under the U.S. Endangered Species Act (ESA) due to a dramatic and ongoing decline in its populations and a significant contraction of its historical range. The International Union fo