RESUMEN
Species delimitation is a major topic in systematics. Species delimitation methods based on molecular data have become more common since this approach provides insights about species identification via levels of gene flow, the degree of hybridization and phylogenetic relationships. Also, combining multilocus mitochondrial and nuclear DNA leads to more reliable conclusions about species limits. Coalescent-based species delimitation methods explicitly reveal separately evolving lineages using probabilistic approaches and testing the delimitation hypotheses for several species. Within a multispecies, multilocus, coalescent framework, we were able to clarify taxonomic uncertainties within S. cyanostictus, an endangered lizard that inhabits a narrow strip of the Chihuahuan Desert in Mexico. We included, for the first time in a phylogenetic analysis, lizards from the three populations of S. cyanostictus recognized so far (East Coahuila, West Coahuila and Nuevo León). Phylogenetic analysis corroborates the hypothesis of two separately evolving lineages, i.e. the East and West Coahuila populations, as proposed in a previous study. We also found a distant phylogenetic relationship between the lizards from Nuevo León and those of East and West Coahuila. Finally, based on the species delimitation results, we propose and describe a new species of Sceloporus: S. gadsdeni sp. nov.
