In this study the author analyzes the phylogenetic relationships among the genera and species of alligator lizards (Squamata: Anguidae: Gerrhonotinae). The subfamily consists of six monophyletic genera: Coloptychon , Gerrhonotus , Elgaria , Barisia , Mesaspis , and Abronia . The author reviews the history of gerrhonotine taxonomy, provides a key to, and diagnoses of, all gerrhonotine taxa, and discusses taxonomic and biogeographic implications of...