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 Euneomys petersoni J. A. Allen 1903 Euneomys petersoni J. A. Allen 1903 , Bull. Am. Mus . Nat. Hist., 19: 192 . Type Locality: Argentina , Santa Cruz Prov. , upper Río Chico, near the Cordilleras. Vernacular Names: Peterson's Euneomys . Synonyms: Euneomys dabbeni Thomas 1919 . Distribution: WC Argentina ( Neuquen Prov. ) and C Chile ( Santiago Prov. ) southwards to extreme S Argentina and adjacent Chile , excluding Tierra del Fuego; limits uncertain. Conservation: IUCN – Lower Risk (lc). Discussion: Relegated to a subspecies or full synonym of E. chinchilloides by most systematists ( Gyldenstolpe, 1932 ; Hershkovitz, 1962 ; Mann, 1978 ; Muñoz Pedreros, 2000; Pearson, 1995 ; Pearson and Christie, 1991 ; Reise and Gallardo, 1990 ; Yañez et al., 1987). While examples of both E. chinchilloides (e.g., FMNH 50600, 50601, 50736; USNM 482138-482140) and E. petersoni (e.g., FMNH 50583, 50584-50593, 50595-50599; USNM 84197, 84200, 84202) possess upper incisors with distinct mediolateral grooves, the series otherwise differ in size and color, abrupt contrasts over relatively short geographic distances that persuaded Osgood (1943) to maintain each as species. A strong size separation is actually conveyed in the morphometric analysis of Reise and Gallardo (1990 :Fig. 3), which employed all variables and in which samples of chinchilloides proper are non-overlapping in multivariate space (Note that certain operational taxonomic units defined by those authors are undoubtedly species composites, a situation that affects measures of intra-sample covariation and compromises statistics of inter-sample dispersion). As implied by the range limits, we tentatively assign those northern samples that co-occur with E. mordax to E. petersoni , but, as noted by Pine et al. (1979) , they do not convincingly fit with either E. chinchilloides or E. petersoni as known by populations in S Chile and Argentina . Until such problems and differences can be resolved in the context of a substantive generic revision, using larger samples and other kinds of data, we continue to follow Osgood (1943) . Karyotype (2n = 36, FN = 66) reported by Reise and Gallardo (1990 , as E. chinchilloides ).