Elliptio angustata I. Lea, 1831
Anodontoides angustifrons (FOSSIL) (F. McCoy, 1851 †)
Parreysia annandalei H.B. Preston, 1912
Quadrula apiculata T. Say, 1829
Elliptio aquila (I. Lea, 1857)
Micronaias arata (I. Lea, 1845)
Elliptio arca T.A. Conrad, 1834
Epioblasma arcaeformis (I. Lea, 1831)
Anemina arcaeformis (P.M. Heude, 1877)
Anemina arcaeformis flavotincta (E.C. Von Martens, 1905)
Elliptio arctata T.A. Conrad, 1834
Unio arcuatus N.R. Bouchard-Chantereaux,1838
Alasmidonta arcula I. Lea, 1838
Obovaria arkansasensis (I. Lea, 1862)
Fusconaia askewi (W.A. Marsh, 1896)
Amphinaias asperata (I. Lea, 1861)
Unio asturianus (FOSSIL) G. Delvene & al., 2016 †
Pleurobema athearni Gangloff, G.C. Williams& Feminella, 2006
Alasmidonta atropurpurea C.S. Rafinesque, 1831
Amphinaias aurea (I. Lea, 1859)
Pseudodon aureus P.M. Heude, 1885
Acuticosta aurorea (P.M. Heude, 1883)
Hamiota australis (C.T. Simpson, 1900)
Pseudodon avae (W. Theobald, 1873)
Prisodontopsis aviculaeformis F.R. Woodward, 1991
Nephronaias aztecorum (R.A. Philippi, 1847)
Coelatura bakeri (C.B. Adams, 1866)
Lithodomina bakhensis (FOSSIL) Reed, 1944 †
Fusconaia barnesiana (I. Lea, 1829)
Lamprotula bazini (P.M. Heude, 1877)
Pleurobema beadleianum (I. Lea, 1861)
Cristaria beirensis Y.Y. Liu & W.Z. Zhang,1982
Unionelloides bellalensis (FOSSIL) D. Van Damme & A. Bogan,2015 †
Anodonta beringiana (A.T. von Middendorff,1851)
Parreysia bhamoensis W. Theobald, 1873