Microryzomys Thomas, 1917 . Smithson. Mise. Coll., 68:1.

TYPE SPECIES: Hesperomys minutus Tomes, 1860 .

SYNONYMS: Thallomyscus .

COMMENTS: Oryzomyine. Named as a subgenus of Oryzomys and either retained as such (Cabrera, 1961; Ellerman, 1941; Osgood, 1933a) or placed in synonymy with Oligoryzomys (Gyldenstolpe, 1932; Tate, 1932e; Thomas, 1926c). Junior synonymy of Thallomyscus established by Osgood (1933a). Raised to genus by Carleton and Musser (1984) and later revised by them (1989).