Sigmodon Say and Ord, 1825 . J. Acad. Nat. Sci. Philadelphia, 4(2):352.

TYPE SPECIES: Sigmodon hispidus Say and Ord, 1825 .

SYNONYMS: Deilemys, Lasiomys, Sigmomys .

COMMENTS: North American forms revised by Bailey (1902), with subsequent partial revisions by Baker (1969), Voss (1992), and Zimmerman (1970); further alphataxonomic study dearly needed. Standard karyology summarized by Zimmerman (1970), banded karyotypes by Elder (1980) and Elder and Lee (1985), albumin differentiation by Fuller et al. (1984). Skin-skull morphology (Bailey, 1902; Baker, 1969) and karyology (Elder and Lee, 1985; Zimmerman, 1970) have yielded conflicting pictures of species-group associations. Sigmomys, type species Sigmodon alstoni, variously treated as a distinct genus (Handley, 1976), a subgenus of Sigmodon (Husson, 1978), or a full synonym (Cabrera, 1961). Hershkovitz (1955a) arrayed Sigmodon with Holochilus, Neotomys, and Reithrodon as the sigmodont group, but other evidence has questioned the close affinity of each to Sigmodon (see those generic accounts).