We describe the second known tetraploid amniote that reproduces by parthenogenetic cloning. This all-female species of whiptail lizard originated in the laboratory from hybridization between Aspidoscelis uniparens (triploid parthenogen) and Aspidoscelis inornatus (diploid bisexual species). Similar clonal lineages of tetraploids arose from at least 44 F1 hybrid females. These were produced by at least 15 A. uniparens that mated with several different males of A. inornatus from both New Mexico and Arizona stock.
Inheritance of alleles at eight microsatellite deoxyribonucleic acid (msDNA) loci in the tetraploid species confirms its parentage, whereas DNA quantification and behavior of chromosomes in meiosis demonstrate that tetraploidy and heterozygosity are maintained generation after generation.
We compared univariate and multivariate variation in scalation between the tetraploids, their parental taxa, and four museum specimens from New Mexico that were reported as putative hybrids. Two of the putative hybrids are confirmed as such, but the other two are A. inornatus. The similarities of A. uniparens and the tetraploids suggest that tetraploid females may exist in old samples misidentified as A. uniparens. Clones of the tetraploid species are so similar to each other in morphology and msDNA that we have been unable to distinguish most individuals or separate lineages from the P1 through multiple generations (up to F7) on the basis of the 12 msDNA loci analyzed in this study.
We discuss taxonomic aspects of the multiple hybrid origins of similar clones and apply one specific name. For some systematists, depending on the species concept preferred, these lizards represent a complex of multiple cryptic species that cannot be reliably identified or diagnosed (one species for each F1 hybrid female that cloned a lineage). These specimens of known parentage provide valuable insights for taxonomic treatment of natural parthenogenetic clones. In addition, we show that the degree of morphological variation in clonal parthenogens and bisexual A. inornatus can be similar to each other.