A new species of Thamnophis (Serpentes, Colubridae) from Jalisco, Mexico, with a discussion on the phylogeny, taxonomy, and distribution of snakes related to Thamnophis scalaris

Garter snakes in the genus Thamnophis from Mexico have a long and convoluted taxonomic history. From 2015 to 2022, we conducted a comprehensive sampling of Mexican Thamnophis species, aiming to link molecular phylogenies with the recognized species related to T. scalaris in the highlands of Mexico. Here, we present an analysis of mitochondrial DNA to resolve the status of two enigmatic highland Thamnophis populations. Our research resulted in the identification and morphological characterization of a previously undescribed Thamnophis species from the state of Jalisco in western Mexico. We also clarify the identity and relationships of several previously enigmatic populations of Thamnophis. This work presents new data for Thamnophis phylogenetics from the Mexican highlands and offers a framework for future conservation efforts.