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Subspecies have most often been described qualitatively with small sample sizes as excerpted from geographic continua. They present a long-standing conflict with evolutionary and statistical principles as well as conservation planning that often relies upon a phylogenetic perspective. Herpetological subspecies have been recognized in the literature as exceeding numerical expectations and subsequent reevaluations during the last decade have decreased their numbers ,50%, the exception being whiptail lizards (Aspidoscelis, family Teiidae). Here we used 842 base pairs of mitochondrial (mt) DNA to examine potential taxonomic and conservation boundaries among two putative species and four subspecies of the abundantly polytypic Aspidoscelis inornata (Little Striped Whiptail Complex, LSWC) of southwestern North America. Body coloration, but not mtDNA, distinguished two putative species inhabiting alkali deposits, whereas neither dataset could diagnose three paraphyletic subspecies. A trend to elevate putative subspecies following a more contemporary evaluation is premature for the LSWC: we suggest that two species (arizonae, pai) and three subspecies (gypsi, junipera, llanuras) lack molecular and morphological differentiation and thus should be rescinded in taxonomic rank. These uncertainties concerning the LSWC with regard to its distributions and relationships impinge upon conservation proposals that, for example, seek to list A. arizonae as ‘threatened’ under the Endangered Species Act.

Lizards of the gonochoristic Aspidoscelis inornata (Little Striped Whiptail) complex are ubiquitous components of vertebrate faunas in diverse habitats in the southwestern United States and northern Mexico. One of these, Aspidoscelis arizonae ( = A. inornata arizonae, Arizona Striped Whiptail), is extant at only a few grassland areas in southeastern Arizona, but nonetheless played an important evolutionary role in the hybrid origins of seven obligatory parthenogenetic species. Although recognized as a distinct species by many, A. arizonae lacks a valid species description and only anecdotal data argue for its recognition. We were unable to separate it from geographically proximate A. inornata in southwestern New Mexico, using diagnostic morphological features (i.e., number of stripes, dark field coloration, sky blue ventral suffusion) previously used to delineate aspidoscelids. Furthermore, we evaluated additional diagnostic characters (i.e., body size plus ten meristic characters) in samples of A. arizon...

The whiptail lizard Aspidoscelis dixoni (Teiidae) comprises three distinctive color pattern classes (i.e., variants); A and B are restricted to Presidio County, Texas, and C is isolated over 500 km to the west-northwest in Hidalgo County, New Mexico. Pattern class E of A. tesselata is widely distributed in Chihuahua, Texas, and New Mexico. Genetic data have verified that these parthenogenetic species are hybrid-derivatives of A. tigris marmorata ♀ X A. gularis septemvittata ♂; however, the number of hybridization events involved in their origin has remained problematic. We used 19 lizards in laboratory skin-grafting experiments to test the histoincompatibility responses among A. dixoni A, B, C, and A. tesselata E. The results of these graft exchanges indicated that individuals of all four pattern classes were mutually histocompatible to skin grafts, a level of genetic homogeneity indicative of the origin of A. dixoni and A. tesselata from the same hybrid lizard. Thus, the color pattern variants A...

The Cnemidophorus laredoensis subgroup of parthenogenetic whiptail lizards comprises clonal complexes A and B, with each form having a mostly allopatric distribution area that includes only a few sites of syntopy with the other form and a distinctive ensemble of morphological characters. The evolution of these clonal complexes is most readily explained by the hypothesis of a hybrid C. gularis × C. sexlineatus derivation for form A, originally described from Laredo, Webb County, Texas, and a second hybridization involving these species to account for form B. Reciprocal skin-grafting, previously used in studies of genetic structure in the parthenogenetic species C. tesselatus, C. neomexicanus, C. uniparens, and C. velox, provides a methodology for differentiating between the descendants of different parthenogenetically capable interspecific hybrids. We used individuals of C. laredoensis A from six sites in Texas and individuals of form B from three of these sites in reciprocal skin-grafting experim...

Cnemidophorus tesselatus is an allodiploid, parthenogenetic lizard comprised of a number of distinctive tokogenetic arrays (Frost and Hillis, 1990) presently identified by four color pattern class descriptors: C, Colorado D, New Mexico D, and E (Taylor et al., 1996; Walker et al., 1997). The macrogeographic relationships of these pattern classes were outlined in Zweifel's (1965) pioneering study of geographic variation in Cnemidophorus tesselatus. Pattern class C was known to exist isolated from the other pattern classes in parts of southeastern Colorado, northwestern Oklahoma, and northwestern Texas. Sympatry between pattern classes C and D was known to occur only in the vicinities of the historic townsite of Higbee, Otero County, Colorado, and Conchas Lake, San Miguel County, New Mexico. Pattern class E occurred to the south, with specimens from Fort Sumner, De Baca County, New Mexico, approximately 105 km south of the Conchas Lake locality, documenting the closest proximity of pattern class E to pattern classes C and D.

At times over 30 years, various authors have expressed conflicting opinions on the composition of the parthenogenetic Cnemidophorus tesselatus complex at Higbee, Otero County, Colorado, the only known site of sympatry between diploid and triploid members of this complex. Recently, some workers have stated that two rather than three distinctive parthenogens occur at Higbee, one being an undescribed triploid species (tentatively designated pattern class C), which resulted from hybridization between C. tesselatus D(2n) and gonochoristic C. sexlineatus. Alternatively, our study identified two diploid pattern classes [C(2n) and D(2n)] and one triploid pattern class [B(3n)] among specimens of C. tesselatus from Higbee (including those with electrophoretically determined ploidy levels). We used two canonical variate analyses (CVA) to test hypotheses concerning the identity and origin of the triploid form. CVA1 suggested that specimens of the Higbee triploid form represented C. tesselatus B(3n), not an undescribed species. CVA2 suggested that C. tesselatus B(3n) was derived from a C. tesselatus C(2n) x C. sexlineatus hybrid, not a hybrid involving C. tesselatus D(2n).