Unio mamillatus (FOSSIL) Hislop, 1859 †
Unio mancus J.B.P.A. Lamarck, 1819 Spain79 mm
Unio mancus hamyanus J.R. Bourguignat, 1885 Ethiopia
Unio mancus ilqui Soleillet, 1885 Ethiopia
Parreysia mandelayensis W. Theobald, 1873 Mandalay, Myanmar
Lamprotula mansuyi (P. Dautzenberg& H. Fischer, 1908) Vietnam, Tonkin
Pseudodon manueli Konopleva, Kondakov& Vikhrev, 2017
Lamellidens marginalis (J.B.P.A. Lamarck, 1819) Sri Lanka56 mm
Alasmidonta marginata T. Say, 1818 Illinois35,4 mm
Pleurobema marshalli L.S. Frierson, 1927 Alabama, Greene County
Elliptio marsupiobesa S.L.H. Fuller, 1972 Tennessee, Cumberland County
Psoronaias martensi L.S. Frierson, 1927 Guatemala
Fusconaia masoni (T.A. Conrad, 1834) South Carolina
Alasmidens mccordi (E.W. Athearn, 1964) Alabama, Coosa River
Toxolasma mearnsi C.T. Simpson, 1900 USA, Texas55 mm
Actinonaias medellina (I. Lea, 1838) Mexico, Veracruz
Nephronaias mellea (I. Lea, 1859) Mexico
Unio menkei (FOSSIL) F.C.L. Koch& R.W. Dunker, 1847 † Germany, Obernkirchen
Protunio messageri (A.R.J.B. Bavay& P. Dautzenberg, 1901) Vietnam, Tonkin
Popenaias metallica (T. Say, 1831) Mexico, San Luis Potosì
Theliderma metanevra (C.S. Rafinesque, 1820) Alabama66,9 mm
Epioblasma metastriata T.A. Conrad, 1838 Georgia, Etowah river
Potamilus metnecktayi R.I. Johnson, 1998 Mexico, Tamaulipas
Sphenonaias mexicana (R.A. Philippi, 1847) Texas, Mason County
Oxynaia micheloti (L.J. Morlet, 1886) Malaysia
Oxynaia micheloti hedeius (J.F. Mabille, 1889) Vietnam
Sphenonaias microdon (E.C. Von Martens, 1887) Guatemala
Physunio micropteroides T.N. Annandale, 1918 Magway, Myanmar
Physunio micropterus (P.M.A. Morelet, 1866) Cambodia
Lamprotula microsticta (P.M. Heude, 1877) Dongting lake, Hunan, China129 mm
Pseudanodonta middendorffi (Siemaschko, 1848) Austria
Fusconaia mitchelli (W.H. Dall, 1896) Texas, Victoria County
Actinonaias moctezumensis (H.A. Pilsbry, 1910) Mexico, San Luis Potosì
Physunio modelli R.A.M. Brandt, 1974 Thailand59,88 mm
Pressidens moellendorffi F. Haas, 1910 Philippines, Palawan Island