A taxonomic study on the South American dwarf boas of the genus Tropidophis revealed the
existence of two new species in the Atlantic Forest biome. As a result, we recognize five mainland species,
three in the Atlantic Forest and two in northwestern South America. Based on general distribution and
morphological orientation, the type locality of T. paucisquamis is restricted to Estac¸a˜o Biolo´ gica de Borace´ ia
(EBB), municipality of Saleso´ polis, state of Sa˜o Paulo, Brazil; furthermore, a lectotype for T. taczanowskyi is
designated. We provide data on the hemipenial morphology of two South American Tropidophis, showing
that the quadrifurcate condition described for West Indian taxa also occurs in mainland congeners. The
distributions of the three Atlantic Forest species are congruent with patterns of diversification of other
vertebrate taxa associated with cold climates prevalent at high elevations. Refugial isolation and riverine
barriers may account for such speciation events.