Coelatura ratidota (Charmes, 1885)
Elliptio raveneli T.A. Conrad, 1834
Alasmidonta raveneliana I. Lea, 1834
Nephronaias ravistella (P.M.A. Morelet, 1849)
Unio ravoisieri G.P. Deshayes, 1847
Ligumia recta (J.B.P.A. Lamarck, 1819)
Lampsilis reeveiana (I. Lea, 1852)
Obliquaria reflexa C.S. Rafinesque, 1820
Amphinaias refulgens (I. Lea, 1868)
Unio regularis (FOSSIL) Fric, 1869 †
Inversiunio reinianus (W. Kobelt, 1879)
Pseudodon resupinatus E.C. Von Martens, 1902
Acuticosta retiaria (P.M. Heude, 1883)
Reticulatus reticulatum (FOSSIL) (Phillips) †
Reticulatus reticulatus (C.T. Simpson, 1900)
Obovaria retusa J.B.P.A. Lamarck, 1819
Pleurobema riddellii I. Lea, 1861
Lemiox rimosus C.S. Rafinesque, 1831
Solenaia rivularis (P.M. Heude, 1877)
Elliptio roanokensis I. Lea, 1838
Alasmidonta robusta A.H. Clarke, 1981
Lamprotula rochechouarti (P.M. Heude, 1875)
Coelatura rothschildi (H. Neuville& J.G. Anthony, 1906)
Coelatura rotula H.A. Pilsbry& J.C. Bequaert, 1927
Fusconaia rotulata (B.H. Wright, 1899)
Glebula rotundata (J.B.P.A. Lamarck, 1819)
Potamilus rovirosai (H.A. Pilsbry, 1900)
Nephronaias rowellii (I. Lea, 1859)
Pleurobema rubellum T.A. Conrad, 1834
Martensnaias rubicunda (E.C. Von Martens, 1900)
Pleurobema rubrum C.S. Rafinesque, 1820
Psorula rudis (C.T. Simpson, 1900)
Cuneopsis rufescens (P.M. Heude)
Parreysia rugosa (J.F. Gmelin, 1791)
Pachynaias rugososulcata (I. Lea, 1866)