Epioblasma obliquata (C.S. Rafinesque, 1820) USA, Ohio
Radiatula occata (I. Lea, 1860) India, Bombay
Ptychobranchus occidentalis (T.A. Conrad, 1836) Arkansas
Elliptio occulta (I. Lea, 1843) Florida50 mm
Leptodea ochracea (T. Say, 1817) Canada, Nova Scotia
Sinanodonta ogurae (J.T. Kuroda & T. Habe,1987) Japan
Potamilus ohiensis C.S. Rafinesque, 1820 Arkansas72,7 mm
Solenaia oleivorus (P.M. Heude, 1877) China, Nanking
Palindonaia oligocenica (FOSSIL) R. Marquet, Lenaerts& Laporte, 2012 † Belgium
Parreysia olivacea B. Prashad, 1930 Myanmar, Magway
Obovaria olivaria C.S. Rafinesque, 1820 Wisconsin84 mm
Radiatula olivaria (I. Lea, 1831) Myanmar, Pegu
Pseudodon omiensis H. von Heimburg, 1884 Japan, Mikawa
Barynaias opacata (J.C.H. Crosse& P.H. Fischer, 1893) Mexico, Tampico
Anodonta oregonensis I. Lea, 1838 California66 mm
Nephronaias oregonensis (I. Lea, 1852) Nicaragua
Elongaria orientalis (Lea, 1840) Indonesia, Java
Lampsilis ornata T.A. Conrad, 1835 Alabama98 mm
Villosa ortmanni (B. Walker, 1925) Kentucky, Hart County
Psoronaias ostreata (P.M.A. Morelet, 1849) Guatemala
Dysnomia othcaloogensis (I. Lea, 1857) USA, Georgia
Lampsilis ovata (T. Say, 1817) Tennessee101 mm
Lampsilis ovata ventricosa D.W. Barnes, 1823 Illinois72,5 mm
Acuticosta ovata (C.T. Simpson, 1900) Han River, Shanyang, China
Pleurobema oviforme T.A. Conrad, 1834 Alabama48 mm
Lanceolaria oxyrhyncha E.C. Von Martens, 1861 Japan, Lake Biwa51,9 mm
Fusconaia ozarkensis (R.E. Call, 1887) Arkansas53 mm
Radiatula pachysoma (W.H. Benson, 1862) India, Assam
Delphinonaias paludosa (P.M.A. Morelet, 1849) Mexico, Tabasco
Disconaias panacoensis (G. von dem Busch in R.A. Philippi, 1843) Mexico, Tampico
Trapezoideus panhai Konopleva, Bolotov& Kondakov, 2017
Inversidens pantoensis (M. von Neumayr, 1899) HuNan, China
Schepmania parcesculpta (E.C. Von Martens, 1903) Borneo, Sandakan
Medionidus parvulus (I. Lea, 1860) Tennessee, Chattanooga
Toxolasma parvus (D.W. Barnes, 1823) Alabama25 mm