Wikipedia
Arkansia
Arkansia is a monotypic genus of freshwater mussels in the family Unionidae, the river mussels. The sole species in the genus is Arkansia wheeleri. Its common names are the Ouachita rock pocketbook and Wheeler's pearly mussel. The genus was named for the state of Arkansas, where the mussel was first discovered. This is a federally listed endangered species of the United States.