Structure, variation, and systematic implications of the hemipenes of liolaemid lizards (Reptilia: Liolaemidae)

Abstract

The structure of copulatory organs is widely used in systematics for both differentiating species and for studying phylogenetic relationships. We describe the hemipenes of 42 species belonging to the genus Liolaemus, representing most of their internal groups. We reported 42 characters, the majority not published previously. We constructed a metatree based on previously proposed phylogenetic studies and optimized the hemipenial characters in this topology. Among the most informative characters are presence or absence of flounces or calyces on the sulcate face, ornamentation of the apex, presence or absence of an asulcate face prominence, and presence of a thickening on the proximal region of the asulcate face. Furthermore, we performed a phylogenetic analysis exclusively with the hemipenial characters, not with the intention of making a phylogeny based on this single set of characters, but rather to demonstrate their significance for the reconstruction of relationships in Liolaemus. The obtained results show that the main clades are recovered. We also compared the hemipenial morphology between closely related species to evaluate its taxonomic importance. We conclude that in Liolaemus, the hemipenes can be used both for the differentiation of species and to provide additional evidence for establishing their phylogenetic relationships.