Order Rodentia - Family Cricetidae Author Wilson, Don E. Author Reeder, DeeAnn text 2005 The Johns Hopkins University Press Baltimore Mammal Species of the World: a Taxonomic and Geographic Reference (3 rd Edition), Volume 2 955 1189 book chapter 0-8018-8221-4 10.5281/zenodo.7316535 Sigmodon (Sigmodon) ochrognathus Bailey 1902 Sigmodon (Sigmodon) ochrognathus Bailey 1902 , Proc. Biol. Soc. Wash., 15: 115 . Type Locality: USA , Texas , Brewster Co., Chisos Mountains, 8000 ft ( 2438 m ). Vernacular Names: Yellow-nosed Cotton Rat . Synonyms: Sigmodon (Sigmodon) baileyi J. A. Allen 1903 ; Sigmodon (Sigmodon) madrensis Goldman and M. C. Gardner 1947 ; Sigmodon (Sigmodon) montanus Benson 1940 . Distribution: SE Arizona , extreme SW New Mexico , and Transpecos, Texas , USA , south to C Durango , México ; northern outlier population may persist in Guadalupe Mtns, Transpecos, Texas (see Stangl and Dalquest, 1991 ). Conservation: IUCN – Lower Risk (lc). Discussion: Subgenus Sigmodon , S. hispidus species group. Basal clade within the S. hispidus assemblage according to phylogenetic interpretations of cytochrome b data ( Peppers et al., 2002 ), not with S. fulviventer and kin ( Baker, 1969 ). Findley and Jones (1960) detected no consistent pattern of size and pelage color variation to justify recognition of subspecies, a conclusion sustained by the low genetic distances recorded among populations ( Carroll et al., 2002 ). See Baker and Shump (1978, Mammalian Species, 97).