A New Subspecies of the Iguanid Lizard, Sceloporus grammicus, from Northeastern Mexico, with Comments on Its Evolutionary Implications and the Status of S. g. disparilis

Abstract

Sceloporus grammicus tamaulipensis is described from the isolated Sierra de Tamaulipas mountain range in southern Tamaulipas, Mexico, where it is apparently restricted to oak and pine-oak habitats of high elevations. It is distinguished from other adjacent races of S. grammicus by its larger scales and, consequently, a much lower number of dorsal scales, and to a lesser extent, scales around mid-body. Males of S. g. tamaulipensis are separated from males of S. g. grammicus, some of which have low numbers of dorsals, by ventral color patterns. This new race is also distinct at two allozyme loci (esterase-1, IDH). Morphometric, color pattern, and chromosome data suggest that S. g. tamaulipensis is most closely related to S. grammicus populations inhabiting the Sierra San Carlos and lowland thorn scrub habitats of northern Tamauli- pas and southern Texas. Sceloporus grammicus disparilis is not clearly differentiated from S. g. microlepidotus and is placed in synonymy with it.