Comparative myology of Leiosauridae (Squamata) and its bearing on their phylogenetic relationships

We present a study of the musculature of the leiosaurids, an ecologically diverse family of lizards that inhabits south-ern South America. Our first goal is to contribute to a better understanding of the anatomical structures, and particularly the muscu-lar features, of leiosaurids and the related polychrotids Anolis sp. and Polychrus sp. To study these myological features in a cladis-tic context, we added 162 new cranial and postcranial myological characters to the 82 morphological characters of FROST et al. (2001) and assembled a matrix including 20 taxa and 244 characters including all leiosaurid genera, and analyzed them cladistically (data set II). We combined and contrasted our own muscular data with the morphological data of FROST et al. (2001) in different data sets (I, II, III) in order to analyze the evidence provided by myology against that provided by osteological and external fea-tures. The Enyaliinae is paraphyletic in all our analysis. In our analyses of data sets II and III, the Leiosauridae appears as a mono-phyletic group. We recovered Leiosaurinae as monophyletic in the analysis of data set II, III, and in the supertree. Leiosaurus genus is monophyletic in all our analyses, except that based on our data set I. Diplolaemus genus is monophyletic in all our analyses. Pristidactylus genus is a clade in our analyses of data sets II and III, while Enyalius genus appears as monophyletic in our analyses of data sets I, II and III. Anisolepis and Urostrophus genera are monophyletic in our supertree.