Aspidoscelis exsanguis

Reeder et al. (2002) examined phylogenetic relationships of the whiptail lizards of the genus Cnemidophorus based on a combined analysis of mitochondrial DNA, morphology, and allozymes. They determined that Cnemidophorus in the traditional sense is paraphyletic and thus in need of nomenclatural revision. Rather than subsume all cnemidophorine species (including Kentropyx) in a single large genus (Ameiva), they proposed a split that placed the North American "Cnemidophorus" clade in the monophyletic genus Aspidoscelis; under this arrangement, South American taxa remain in the genus Cnemidophorus.

This species is a parthenogenetic allotriploid of hybrid origin. Allozyme and mDNA data indicate that C. exsanguis probably arose by the hybridization of C. septemvittatus or C. scalaris with an allodiploid intermediate form (or forms) created by one or more earlier hybridization events involving a male C. inornatus and a female C. costatus or C. burti stictogrammus (see Stuart 1991). Putative similarity to C. flagellicaudus and C. sonorae is overrated according to Frost and Wright (1988). This species formerly was included in other species of the sexlineatus species group. See Stuart (1991) for a review of the nomenclatural history of this species.

The range extends from the upper Rio Grande, Pecos River, and Canadian River valleys of New Mexico southward through western Texas to central Chihuahua (Rio Conchos and Rio Papigochic drainage basins) and westward to southeastern Arizona and northeastern Sonora, at elevations of 760-2,440 meters (2,500-8,000 feet) (Stuart 1991).

This species is represented by hundreds of occurrences or subpopulations (e.g., see maps in Stuart 1991 and Degenhardt et al. 1996).

No major threats have been identified.