Parthenogenetic Cnemidophorus tesselatus complex (Sauria: Teiidae): A neotype for diploid C-tesselatus (Say, 1823), redescription of the taxon, and description of a new triploid species

Since 1967, the name Cnemidophorus tesselatus (Say, 1823) has been in use for a hybrid-derived complex of whiptail lizards known to include both diploid and triploid parthenogenetic populations distributed in parts of Colorado, Oklahoma, New Mexico, Arizona, Texas, and Chihuahua (Mexico). Application of new binomial nomenclature to additional populations in the complex has long been delayed by philosophical disagreement among workers as to what constitutes a parthenogenetic species of Cnemidophorus in addition to the daunting operational challenge of constructing workable diagnoses for arguably different populations. We concur with a body of opinion that, presently, C. dixoni Scudday, 1973 is the appropriate name for certain disjunct diploid populations of lizards in Hidalgo County, New Mexico, and Presidio County, Texas, despite the fact that some workers continue to allocate these populations to C. tesselatus. We have redefined the remaining diploid populations derived from hybridization between C. marmoratus marmoratus (=C. tigris) and C. gularis septemvittatus (=C. septemvittatus) as an evolutionary species for which the name C. tesselatus was available. To affect stability in the assignment of this name, we designate a neotype and rediagnose the taxon which is geographically distributed in the states previously noted for the complex. We allocate triploid populations derived from hybridization between normally parthenogenetic C. tesselatus and gonochoristic C. sexlineatus to a cytogenetically and morphologically distinct new species restricted to parts of four counties in southeastern Colorado. We found no evidence that the triploid population of lizards in and near Ninemile Valley of the Purgatoire River, Otero County, Colorado should be assigned to a second triploid species as was recommended by some previous authors. All specimens of C. dixoni, C. tesselatus, and the new triploid species were identifiable by highly diagnostic features of dorsal color and/or pattern (i.e., configuration of the stripes on the body and pattern of spots and/or bars on the body, posterior surfaces of the thighs, and base of the tail) evident under both field and laboratory conditions. Each of these species includes either distinctive classes of color pattern or morphological variants subject to further evaluation for taxonomic recognition. Sympatry between C, tesselatus and the triploid species was noted only in and near Ninemile Valley, Colorado; sympatry between C. tesselatus and C. dixoni has been reported only in Pinto Canyon, Presidio County, Texas.