Morphological diversity and phylogenetic relationships within a South-American clade of iguanian lizards (Liolaemidae: Phymaturus)

Abstract

With 36 species and at least nine potentially independent lineages (not formally described yet) occurring mostly in theAndes and adjacent Patagonia and Puna plateau areas, Phymaturus lizards represent one of the most endemic vertebrategroups of the arid southwestern region of South America. Phylogenetic relationships among species of Phymaturus areinferred using mainly a morphological data set of 206 characters. Also available sequences of mitochondrial DNA for sev-en terminals were added for a total evidence analysis. Most information is included in the discrete characters block; mostcharacters involve color pattern, osteology and squamation. Continuous characters were taken from body proportions,squamation and skeletons. Among morphological data, binary polymorphic characters were analyzed applying the scaledcoding criteria. Continuous characters were entered in the analysis using standardized ranges, a method that allows a sim-ple optimization to estimate distances/costs avoiding the arbitrary coding as discrete characters. For our parsimony anal-yses we chose the implied weights method, which underweights homoplastic characters. Several runs were madeanalyzing all the information combined and also separating morphological from molecular datasets. Binary polymor-phisms were also analyzed as missing data. All characters affected by sexual dimorphism were analyzed separating thesexes; female information was more congruent with the total evidence analysis. Characters involving continuous and poly-morphic information are relevant for searching and building phylogenetic hypotheses in Phymaturus. There exists signif-icant congruence between the molecular information analyzed in this study and previous published analyses. Within bothmain clades of Phymaturus, northern subgroups are those more recently originated during the genus diversification. Spe-cies belonging to the puna subclade of the palluma group are arranged in two natural groups, one distributed in the north(Catamarca and La Rioja provinces), and the other in the south, La Rioja and San Juan provinces. Within the patagonicusgroup, the majority of the species are arranged in a south-central Chubut clade, eastern-central Chubut clade, central Rio Negro clade and a Payunia clade.