Phrynosoma orbiculare is an endemic species of lizards in Mexico and is distributed from the northern part of the country to the central highlands. This species is found in open areas among scrubs, grasses, yuccas, and herbaceous plants. In our study, we performed two multivariate analyses (principal components and discriminant functions) to examine morphological and geographic variation among populations of P. orbiculare at the edge of the southern distribution of the species. Our assessment was to determine the taxonomic status of the subspecies Phrynosoma orbiculare orbiculare, P. o. cortezii, and P. o. boucardi described for this geographic zone. The analyses employed 10 informative diagnostic traits from digitalized images. Our results confirm only two subspecies, P. o. orbiculare and P. o. cortezii, in the study area. In addition, two new localities for the distribution of the species have been included (Nopalillo, Hidalgo, and Amealco, Queretaro). Moreover, the morphometrics of the organisms from new localities revealed that all individuals were positioned in the P. o. cortezii group and that the distribution of this subspecies extends west of the original records. We propose that the two populations reported as P. o. boucardi can be renamed as P. o. cortezii.