Resumen

Species delimitation in groups where taxonomy has been intensively disputed may be clarified by integrating different sources of evidence such as genetics and various dimensions of the phenotype, and by sampling thoroughly across populations. An avian group whose limits are unresolved is the Chlorospingus flavopectus complex, with 28 subspecies inhabiting disjunct cloud forests from Mexico to Argentina. Species limits in the complex are more clear in Mesoamerica, but most populations occur in South America, where phenotypic variation has not been thoroughly analyzed and many subspecies were omitted in previous phylogenetic studies, which found the complex is paraphyletic. Hence, we reconstructed phylogenetic relationships of the whole complex, and focused on Andean C. flavopectus populations and C. semifuscus, one of the species nested within the group, to assess population genetic structure jointly with quantitative analyses of morphometric and vocal variation to test alternative hypotheses of species limits. We found deep phylogenetic relationships in the complex are not resolved, but subspecies form highly supported groups that have unique haplotypes. Variation in morphometrics was mainly restricted to body mass and beak, with one subspecies group being smaller in these traits. Vocally, we found differences in spectral and structural aspects that coincide at a finer scale with phylogenetic groups and follow a leapfrog pattern of geopgraphic variation, in which populations from the Northern and Southern Andes are vocally similar yet distinct from populations of the Central Andes. Variation revealing statistical support for distinct phenotypic groups in regional sympatry suggested that more than one species in the complex exists in South America, but our results did not support species limits implied by current taxonomy or alternative treatments. We propose a preliminary classification that recognizes three species of the complex in South America and better reflects patterns of phenotypic variation and genetic structure among populations. Our results highlight the need of additional studies reassessing species limits of Neotropical organisms, a region where biodiversity remains underestimated.