A phylogeny of the Australian Sphenomorphus group (Scincidae: Squamata) and the phylogenetic placement of the crocodile skinks (Tribolonotus):: Bayesian approaches to assessing congruence and obtaining confidence in maximum likelihood inferred relationships

Australian scincid lizards are a diverse squamate assemblage (similar to385 species), divided among three major clades (Egernia, Eugongylus. and Sphenomorphus groups). The Sphenomorphus group is the largest, comprising 61% of the Australian scincid fauna. Phylogenetic relationships within the Australian Sphenomorphus group and the phylogenetic placement of Tribolonotus are inferred using mtDNA (12S and 16S rRNA genes, ND4 protein-coding gene, and associated tRNA genes; 2185 bp total). These data were analyzed separately (structural RNA vs protein-coding partitions) and combined using maximum likelihood. Confidence in inferred clades was assessed using non-parametric bootstrapping and Bayesian analysis. Analysis of the combined data strongly supports Sphenomorphus group (as well as the Australian subgroup) monophyly. Notoscincus is strongly placed as the sister taxon of the remaining Australian Sphenomorphus group taxa, with this more exclusive clade being divided into two major groups (one restricted to mesic eastern Australia and the other continent wide). The speciose Australian Eulamprus and Glaphyromorphus are both polyphyletic. All remaining non-Sphenomorphus group lygosomine skinks strongly form a clade, with Tribolonotus placed as the sister taxon of the Australian Egernia group. (C) 2003 Elsevier Science (USA). All rights reserved.