Biogeography, natural history and systematics of Cnemidophorus tigris (Sauria: Teiidae) east of the continental divide

Abstract

The ontogenetic, sexual and geographic variation of scutellation and dorsal, throat and ventral patterns of cnemidophorus tigris east of the Continental Divide is examined using univariate and multivariate statistical techniques. The species is interpreted to consist of five subspecies, two described as new. Three subspecies clusters are recognized. The northern subspecies cluster, including C. t. marmoratus and a new form, occurs in New Mexico, western Texas, northern and east-central Chihuahua, western and central Coahuila, and west-central Nuevo Leon; the new form occupies the eastern and southern portions of the range. A central cluster consists only of C. t. pulcher, found in the southeastern tip of Chihuahua, adjacent east-central Coahuila, and extreme northeastern Durango. The southern cluster includes C. t. variolosus and a new subspecies; variolosus occurs in northeastern Durango and southwestern Coahuila; the new form is in southeastern Coahuila and west-central Nuevo Leon. Several zones of intergradation between various combinations of subspecies are found. Features of dorsal, throat and ventral patterns most conspicuously separate the subspecies clusters. Members of the northern cluster have black-flecked throats and venters on a light background, and typical dorsal patterns of boldly reticulated longitudinal lines and transverse bars. The central subspecies cluster includes specimens with undulating transverse light and black bars across the throat, venter suffused anteriorly with black and dorsal patterns boldly marked with light spots, often arranged in transverse bars. The southern cluster includes individuals having black throats and venters and finely reticulated dorsal patterns. The subspecies within the northern and southern clusters are differentiated by divergent scutellation characteristics..