We investigate the taxonomic status of the Texas garter snake, Thamnophis sirtalis annectens, a species of greatest conservation need in Texas. We broadly test the hypothesis that an integrative approach to species conservation has greater utility than using only a single data type (e.g., molecular, morphological, behavioral, or ecological) by demonstrating how ecological niche modeling and molecular genetics can be used synergistically to resolve taxonomic classifications. Using a phylogenetic analysis based on molecular data, we found that some putative T. s. annectens specimens actually represent a co-occurring subspecies (the red-sided garter snake, Thamnophis sirtalis parietalis), which is not of conservation concern. However, both T. s. annectens and T. s. parietalis are genetically distinctive from another co-occurring subspecies, Thamnophis sirtalis sirtalis, and the ecological distinctness of T. s. annectens from T. s. parietalis suggests that T. s. annectens is, in fact, a distinct evolutionary subunit. Only when both genetic and ecological information were included was the distinctiveness of T. s. annectens apparent, thus highlighting the need for integrative approaches in conservation management regardless of the taxa in question.