Variation in Two Sympatric Whiptail Lizards (Cnemidophorus inornatus and C. velox) in New Mexico

Abstract

Cnemidophorus velox (uniparental) and C. inornatus (biparental) are reported as sympatric sibling species in New Mexico. Characteristics of the scutellation of the species were analyzed and compared. Clines oriented north-south through central New Mexico are present in both species. In addition to having subtle morphological distinctiveness, the 2 species are well segregated ecologically; occasionally they occur sympatrically in ecotones between grassland and woodland. The present investigation was undertaken in an attempt to clarify further the taxonomic relationship between Cnemidophorus inornatus Baird and C. velox Springer. At various times these two have been treated as species, subspecies, or synonyms, and have been redescribed at one time or another as new species or subspecies. In 1955, Lowe established the specific status of C. velox on the basis of statistically significant differences in both scutellation and body size as well as marked ecological differences. At that time there was still a hiatus of about 150 miles in the known geographical ranges of C. inornatus and C. velox. It is now possible to report the two species in sympatry. In addition to verifying the species relationship of C. velox (uni- parental) and C. inornatus (biparental), the new material obtained in the present investigation has enabled an analysis of geographic variation in some taxonomic characters commonly used by students of the genus Cnemidophorus. MATERIAL AND METHODS. Field collections, examination of habitats, ob- servations of natural activity patterns and other aspects of behavior were made in 1960-1962. In all, 147 specimens of C. inornatus and 135 of C. velox from New Mexico were examined. They are deposited in the Museum of Southwestern Biology (MSB) of The University of New Mexico, Albuquerque, in the Museum of Zoology of The Uni- versity of Michigan (UMMZ), and in the U.S. National Museum