Taxonomy and geographic variation of Formicivora serrana (Hellmayr, 1929) and Formicivora littoralis Gonzaga and Pacheco, 1990 (Aves: Passeriformes: Thamnophilidae)

Abstract

Formicivora serrana was described by Hellmayr in 1929 from specimens collected in Minas Gerais state, and subspecies F. s. interposita and F. s. littoralis by Gonzaga and Pacheco (1990) from specimens from Minas Gerais and Rio de Janeiro states and Rio de Janeiro state, respectively. According to the latter authors, interposita is intermediate both geographically and morphologically in relation to F. s. serrana and F. s. littoralis. Two years after its description, F. s. littoralis was elevated to species status (Collar et al. 1992) and it has subsequently been considered a species of conservation concern because of its restricted geographical range and threatened habitat. Formicivora s. interposita, however, was not elevated and is generally considered a subspecies of serrana. In this study we review the taxonomy of F. serrana, testing the validity of F. littoralis and proposing the best taxonomic treatment for F. s. interposita. The results of morphometric, vocal and plumage analyses show that F. s. interposita and F. littoralis lack diagnostic characters, and are therefore not valid phylogenetic species. Further, our results indicate that F. littoralis is not a valid biological species, but that it and interposita could be considered subspecies of F. serrana under this species concept. These results stress the need for detailed systematic studies in support of taxonomic decisions.