Ohrigocea ornata (P. Radoman, 1957)
Leiorhagium orokau M. Haase & P. Bouchet,1998
Fluvidona orphana W.B. Miller, W.F. Ponder& K.B. Clark, 1999
Pseudamnicola orsinii (H.C. Küster, 1852)
Saxurinator orthodoxus H. Schütt, 1960
Saccoia oryza (FOSSIL) Š. Brusina, 1893 †
Bythiospeum oshanovae (I. Pintér, 1968)
Pontohydrobia ossovinarum (FOSSIL) (N.I. Andrusov, 1890 †)
Euxinipyrgula ostroumovi (A.N. Golikov& Y.I. Starobogatov, 1966)
Austropyrgus otwayensis A. Clark, W.B. Miller& W.F. Ponder, 2003
Pseudamnicola oudrefica (A. Letourneux& J.R. Bourguignat, 1887)
Bythiospeum ovale (R. Dehm, 1951)
Prososthenia ovata (FOSSIL) (H.G. Bronn, 1831 †)
Belgrandiella ovetensis (E. Rolán, 1992)
Caspiohydrobia oviformis (B.M. Logvinenko& Y.I. Starobogatov, 1968)
Turricaspia ovum B.M. Logvinenko& Y.I. Starobogatov, 1968
Pyrgulopsis owensensis R. Hershler, 1989
Pyrgulopsis owyheensis R. Hershler & H.P. Liu,2009
Marstonia ozarkensis (A. Hinkley, 1915)
Bania pachychila (FOSSIL) (Š. Brusina, 1902 †)
Hydrobia pachygastra A. Paladilhe, 1869
Marstonia pachyta F.G. Thompson, 1977
Belgrandiella pageti H. Schütt, 1970
Pseudamnicola pagoda (FOSSIL) (M. von Neumayr in Herbich& M. von Neumayr, 1875 †)
Pseudamnicola pagodaeformis (FOSSIL) (N.I. Andrusov, 1890 †)
Austropyrgus pagodoides A. Clark, W.B. Miller& W.F. Ponder, 2003
Pyrgulopsis paleoacarinatus (FOSSIL) Czaja & al., 2017 †
Pyrgulopsis paleominckleyi (FOSSIL) Czaja & al., 2017 †
Pseudamnicola pallaryi M. Ghamizi,Vala & Bouka, 1997
Caspia pallasii (S. Clessin & W. Dybowski,1887)
Sogdamnicola pallida (E.C. Von Martens, 1874)
Islamia pallida B. Arconada & M.A. Ramos,2006
Beddomeia pallida W.F. Ponder & K.B. Clark,1993
Jardinella pallida W.F. Ponder & K.B. Clark,1990
Pseudamnicola palmariggii (FOSSIL) D. Esu & O. Girotti,2010 †