Sigmodontomys J. A. Allen, 1897 . Bull. Am. Mus. Nat. Hist., 9:38.

TYPE SPECIES: Sigmodontomys alfari J. A. Allen, 1897 .

COMMENTS: Oryzomyine. Named as a genus but later viewed as a synonym of Nectomys (Ellerman, 1941; Gyldenstolpe, 1932), usually ranked as a subgenus (Hershkovitz, 1944). Hershkovitz (1944:71) stressed the weakness of their association: "The apparent relationship of Sigmodontomys to Nectomys ... is probably attributable to an independant development...from the common oryzomyine stock rather than to a divergence from a...more recent Nectomys-like stock," an assessment later corroborated by other data (Gardner and Patton, 1976; Hooper and Musser, 1964a). Gardner and Patton (1976) formally transferred Sigmodontomys to a subgenus of Oryzomys, and we here provisionally list it as genus, noting the need to refine its relationships to Oryzomys proper .