Tropidurus Wied, 1825, is one of the most ubiquitous lizard genera distributed in open habitats of tropical and subtropical South America. Nevertheless, the broad representation of specimens of this group in scientific collections is hardly reflected in our knowledge of its taxonomic diversity. Most species currently assigned to Tropidurus began to be uncovered in the early 1980's and additional populations in need of formal taxonomic treatment have been cataloged ever since. Herein, we name Tropidurus sertanejo, n. sp., a new species of the T. torquatus group endemic to the semiarid Brazilian Caatinga. Tropidurus sertanejo, n. sp., is currently known from two isolated populations in the municipalities of Caetité and Ibotirama, State of Bahia, Brazil. This is the only species of the T. torquatus group lacking granular mite pockets on the lateral neck, and it is also diagnosable by having a conspicuous bronze-colored head, a light-brown dorsal body with small pale salmon spots, and small body size in comparison with most congeners. Phylogenetic analyses recovered a paraphyletic Tropidurus, but firmly supported T. sertanejo, n. sp., as member of a monophyletic T. torquatus species group. Trees generated by independent analyses of nuclear and mitochondrial sequence data conflicted with our total evidence phylogenetic hypotheses. Since topological disagreements were detected among phylogenetic trees resulting from maximum parsimony (MP) and maximum likelihood (ML) reconstructions, and MP analyses do not require distinct evolutionary models or partition schemes to be defined prior to conduction of phylogenetic reconstruction, these factors were considered unlikely to explain all the variation in the observed results, favoring the interpretation of conflicting phylogenetic signal. Because detailed information on the distribution, population size, and ecological requirements of T. sertanejo, n. sp., are currently unavailable, we recommend the species to be listed as “data deficient” following the rules proposed by IUCN.
