Aspidoscelis marmoratus

Dessauer and Cole (1991) presented evidence of both differentiation and interbreeding between A. marmorata and A. tigris along a transect near the southern part of the border between Arizona and New Mexico, including a narrow (3 km) hybrid zone in which hybrid indices based on color patterns and allele frequencies changed abruptly in concordant step clines. Although those authors interpreted their data as reflecting incomplete speciation between the two forms (i.e., a single species), the same data can be interpreted alternatively as reflecting largely separate gene pools (i.e., two species). Following the terminology of de Queiroz (1998) they are considered incompletely separated species (Crother 2017).

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.

Southern New Mexico and western Texas (Trans-Pecos area, including Big Bend region, with isolated populations in south Texas around Laredo and in sandy region at base of panhandle east of Lubbock; Garrett and Barker 1987) south through e. Chihuahua and southern Coahuila.