A new genus and species of microteiid lizard is described from a series of specimens obtained in the leaf litter at Una (15u109S, 39u039W) in the Atlantic forest of southern Bahia, Brazil. It is characterized by the presence of prefrontals, frontoparietals, parietals, and interparietal; parietals longer than wide; distinct ear openings and eyelids; two pairs of genials, absence of collar and occipital scales; dorsal scales anteriorly smooth and becoming gradually lanceolate and mucronate posterior to the forelimb; and four regular transverse series of smooth ventrals that are longer than wide, identical in size. A phylogenetic analysis based on external morphology, osteology, and molecular data confirms this new lizard as a member of the Heterodactylini radiation of Gymnophthalminae. The topology recovered by maximum parsimony (MP) analyses reveals that its closest relatives are the sister taxa Colobosaura modesta and Iphisa elegans (BS 5 , 50%; Bremer value 5 2) and the partitioned Bremer indexes indicated that the largest contribution to this relationship comes from morphology; Colobosaura mentalis, for which a new generic name is here proposed, is basal to this radiation. Our analyses confirm a previous hypothesis suggesting Stenolepis as a member of the Heterodactylini radiation and that the clade composed of Colobodactylus and Heterodactylus is the sister group of the clade formed by Colobosaura mentalisStenolepis (BS 5 100; Bremer value 5 18), Colobosaura modesta-Iphisa (BS 5 , 50%; Bremer value 5 1), and the new genus here described. The support for Heterodactylini monophyly, on the basis of combined MP analyses is higher (BS 5 96, Bremer value 5 11) than that previously found in molecular-based studies only. Partitioned Bayesian methodology combining molecular and morphological data sets recovered the new genus as the sister taxon (PP 5 0.94) of the clade (PP 5 0.94) formed by I. elegans-C. modesta (PP 5 0.51) and C. mentalis-S. ridleyi (PP 5 1.0). An alternative topology demonstrating a paraphyletic Heterodactylini is only weakly supported (PP 5 0.63). Based on the MP topology we discuss tentative scenarios for the evolution of Heterodactylini.
INTRODUCTIONThe Gymnophthalmidae represent a large South and Middle American radiation (41 genera and about 180 species) of small to medium-sized lizards occurring in terrestrial, arboreal, fossorial, and semiaquatic habitats extending from sea level to the high Andes (Pellegrino et al., 2001;Doan, 2003;Doan and Castoe, 2005;Rodrigues et al., 2005). Taxonomic study of these so-called ''microteiid'' lizards (Ruibal, 1952) has been complicated by the rarity of specimens in collections, which limits studies of geographical and individual variation, and convergence in character complexes (e.g., body elongation, limb reduction, earlessness, lack of eyelids, and the fusion/fission of some major head scales), which has rendered higher-level taxonomy of the Gymnophthalmidae problematic. Boulenger (1885) first organized their chaotic taxonomy by recognizing three...