Calomys Waterhouse, 1837 . Proc. Zool. Soc. Lond., 1837:21.

TYPE SPECIES: Mus (Calomys) bimaculatus Waterhouse, 1837 (= Mus laucha Fischer, 1814).

SYNONYMS: Hesperomys .

COMMENTS: Phyllotine. Cladistic position unclear, but generally viewed as a primitive clade relative to other phyllotine genera (Hershkovitz, 1962; Pearson and Patton, 1976). Possible relationship of Calomys to North American Pliocene form Bensonomys debated by Baskin (1978, 1986) and Reig (1980). Generic revision by Hershkovitz (1962), who reduced the previously-recognized 10-15 species (e.g., Cabrera, 1961; Ellerman, 1941) to only four, two of which, laucha and callosus, have been later shown to be species complexes (Corti et al., 1987; Massoia et al., 1968; Pearson and Patton, 1976; Reig, 1986; Williams and Mares, 1978). Regional names, however, are sometimes employed in contradictory or inconsistent fashion, which leaves unsettled the question of relationship to extraregional forms and the identification of older synonyms to be employed. The species listed here, their distributional extent, and the allocation of synonyms must be viewed cautiously pending another generic revision.