Reithrodontomys zacatecae Merriam, 1901 . Proc. Washington Acad. Sci., 3:557.

TYPE LOCALITY: Mexico, Zacatecas, Sierra de Valparaiso .

DISTRIBUTION: W Chihuahua to WC Michoacan, Mexico.

SYNONYMS: obscurus .

COMMENTS: Subgenus Reithrodontomys, megalotis species group. Hooper (1952) noted the phenetic distinction of zacatecae from R. megalotis saturatus in Jalisco and Michoacan but elected to retain it as a subspecies. Karyotypic divergence of zacatecae reported by Hood et al. (1984), who proposed its elevation to species. Distributional limits, morphological discrimination, and assignment of species-group synonyms deserve amplification.