Unraveling the black banded gecko: a phylogenetic and phenotypic analysis of Coleonyx fasciatus (Boulenger, 1885; Squamata, Eublepharidae), with the description of two new species from Sonora and Sinaloa, Mexico

We use morphological and molecular data to demonstrate that Coleonyx fasciatus , as currently recognized, comprises three divergent lineages. Our integrative analysis supports species-level divergence among these lineages, and we describe two new species in the genus Coleonyx . We discuss this elusive group of eublepharid geckos and review how more than 140 years of taxonomic ambiguity obscured the phenotypic distinctions among the three forms in the historical literature. Additionally, we provide a redefinition of Coleonyx fasciatus , a revised phylogeny for the genus, and updated geographic distributions for the black banded geckos of Mexico. Finally, we assess the vulnerability scores of the three species and provide conservation recommendations.