Oryzomys Baird, 1858 . Mammalia in Repts. U.S. Expl. Surv., 8(1):458.

TYPE SPECIES: Mus palustris Harlan, 1837 .

COMMENTS: Oryzomyine. A taxonomically complex and nomenclaturally confused group whose generic definition was successively broadened by Goldman (1918), Tate (1932d, e), and Ellerman (1941). By the time of Cabrera (1961), the genus embraced as subgenera Melanomys, Microryzomys, Nesoryzomys, Oecomys, and Oligoryzomys — an agglomeration of taxa perhaps as evolutionarily divergent from one another and from Oryzomys sensu stricto as Neacomys and Nectomys, forms traditionally accorded generic status (see Carleton and Musser, 1989:52). Others have recognized all of these or various ones as genera (e.g., Thomas, 1917c; Gyldenstolpe, 1932; Gardner and Patton, 1976; Reig, 1986), as we do here; see appropriate generic accounts for taxonomic histories. Karyotypic information for many species supplied by R. J. Baker et al. (1983a), Gardner and Patton (1976), and Haiduk et al. (1979); for morphological surveys, see Carleton (1973,1980), Hooper and Musser (1964a), and Voss and Linzey (1981). Much basic alpha-revision yet required.