Fig. 1. Geographic range of the western whiptail lizard, Cnemidophorus tigris sensu lato, in the continental southwestern United States and northern Mexico. Rectangle (SE Arizona and SW New Mexico) outlines the contact region (detailed in figs. 3–5) where C. t. punctilinealis interbreeds with C. t. marmoratus. Numbers designate collecting sites (appendix 2) for specimens additional to those obtained within the contact region (fig. 3; appendix 1).