Class Mammalia
Order Rodentia
Family Cricetidae
Subfamily Neotominae
Genus Peromyscus
The Cactus Mouse currently is widespread in the Southwest. It tends to inhabit either the rocky lower slopes of desert ranges or sand dunes built up around mesquite or other bushes. Its current ecology is such that it would not be expected to be in the region during glacial times, though occurrences of disharmonious faunas diminish that argument. Nevertheless, the burden of evidence is higher than if it were an expected taxon.
Peromyscus eremicus overlaps P. maniculatus in discriminant and principal components analyses. Four of 20 modern specimens of P. maniculatus are identified by discriminant analysis as P. eremicus, with discriminant function scores ranging from -0.39 to -2.67 (0 being the separation point between the two taxa). Of seven fossils identified as P. eremicus, scores are -0.61, -0.71, -0.94, -0.94, -0.96, -1.59, and -2.71. Thus the most extreme barely exceeds the deviation seen in the relatively small sample of P. maniculatus. I interpret these figures as indicating the presence of P. eremicus as unproven.
Harris (1987) reported the species from U-Bar Cave on the basis of the specimen noted above with the score of -1.59; excavation notes indicate some disturbance, thus even if the specimen actually is P. eremicus, glacial presence is not certain.
The record from Upper Sloth Cave is suspect in that the species was identified solely by the lack of accessory molar cusps (Logan and Black 1979). As is made clear by Dalquest and Stangl (1983), several other species have significant numbers of individuals lacking accessory structures, and P. eremicus possesses them with fair frequency. The record is retained here, but should be viewed with caution.
Sites.
Late Wisconsin: Mountain View Country Club (Jefferson 2014: cf.); Upper Sloth Cave (Logan and Black 1979).
Late Wisconsin/Holocene: Fowlkes Cave (Dalquest and Stangl 1984b).
Withdrawn: Late Wisconsin, U-bar Cave (Harris 1987; UTEP).
Literature. Dalquest and Stangl 1983, 1984b; Harris 1987; Jefferson 2014; Logan and Black 1979.
Last Update: 12 May 2015