Peromyscus difficilis J. A. Allen 1891

Wilson, Don E. & Reeder, DeeAnn, 2005, Order Rodentia - Family Cricetidae, Mammal Species of the World: a Taxonomic and Geographic Reference (3 rd Edition), Volume 2, Baltimore: The Johns Hopkins University Press, pp. 955-1189 : 1065

Peromyscus difficilis J. A. Allen 1891

Peromyscus difficilis J. A. Allen 1891 , Bull. Am. Mus . Nat. Hist., 3: 298.

Type Locality: México, Zacatecas, Sierra de Valparaíso.

Vernacular Names: Southern Rock Deermouse.

Synonyms: Peromyscus amplus Osgood 1904 ; Peromyscus felipensis Merriam 1898 ; Peromyscus petricola Hoffmeister and de la Torre 1959 ; Peromyscus saxicola Hoffmeister and de la Torre 1959 .

Distribution: W Chihuahua and SE Coahuila, south to C Oaxaca, México.

Conservation: IUCN – Lower Risk (lc).

Discussion: P. truei species group. Revised by Hoffmeister and de la Torre (1961) to include nasutus (see species account below) and comanche (transferred to P. truei —Schmidly, 1973). Karyologic and biochemical evidence has suggested that P. difficilis and P. nasutus are sibling species ( Avise et al., 1979; Zimmerman et al., 1975, 1978); classified as such by Carleton (1989), but see Janecek (1990), who continued to view nasutus populations as part of P. difficilis . DeWalt et al. (1993 b) also noted the somewhat low levels of genetic divergence among attwateri , difficilis , and nasutus (e.g., less than P. gratus versus P. truei ) but retained them as species, as did Tiemann-Boege et al. (2000). The matter of their synonymy merits reconsideration and decisive resolution. Gaona (1997) evaluated sex and age variation of populations in Veracruz and Puebla.