A new species of Leposoma (Squamata: Gymnophthalmidae) with four fingers from the Atlantic Forest central corridor in Bahia, Brazil.

Leposoma sinepollex sp. nov., a new species of the scincoides group, is described from a mountain region in the Atlantic Forest central corridor in state of Bahia, Brazil. The new species is characterized by elongate dorsal and lanceolate ventral scales arranged in diagonal rows, a single and smooth frontonasal, five supraoculars, absence of pollex, third toe as long as or longer than fourth, absence of striations in lower part of head, parietals longer than wide and as long as interparietal, 27-29 dorsals, 25-29 scales around body, 17-19 ventrals, 12-14 total pores in the male (absent in females), 9-10 and 9-11 subdigital lamellae respectively under IV Finger and IV Toe, and strong sexual color dichromatism with a black pigmentation in the ventral parts of males, creamy in females. The new species is morphologically similar to Leposoma nanodactylus, sharing with it among other features the synapomorphic division of the first supraocular. Phylogenetic analyses of 981 bp of combined sequences (cyt b+ ND4) recovered also a strongly supported (PP = 1,0; BP = 100) sister relationship between both species. The new species and Leposoma nanodactylus are placed sister to all the other Atlantic Forest species, with L. baturitensis being the first to diverge in this radiation. We discuss the distribution of the Atlantic Forest Leposoma, as well as possible scenarios for the origin of the new species.