The Elliptio dilatata Group

Elliptio arca (Conrad, 1834) - Mobile River system
Elliptio aquila (Lea, 1857) - Apalachicola and Ochlockonee River systems
Elliptio dilatata (Rafinesque, 1820) - Mississippi River system; Great Lakes and portions of St Lawrence River system
Elliptio jayana (Lea, 1838) - Savannah, St Marys, Oklawaha, Chipola, Suwannee, Choctawhatchee, and Escambia River systems