Phylogeography of the Dendrocolaptes picumnus (Aves: Dendrocolaptidae) species complex: new insights on the diversification of a trans-American lineage

Molecular studies have shown that many polytypic species of birds are paraphyletic and may actually consist of multiple independent species, some of them phenotypically cryptic. One of such cases is Dendrocolaptes picumnus, which was found to be a paraphyletic species, with Dendrocolaptes hoffmannsi nested in it. Recent evidence also showed that multiple independent evolutionary lineages exist in the polytypic D. picumnus that may be characterized as distinct species, however, conclusions were weakened due to small sample sizes. To further evaluate phylogenetic relationships, species limits, and the diversification history of the D. picumnus species complex, herein we performed the densest sampling ever registered for the complex, and analyzed sequences of mitochondrial and nuclear genes from 106 specimens, belonging to all but four taxa grouped in the complex. Our phylogenetic analyses confirmed the monophyly of D. hoffmannsi and D. platyrostris, as well as the paraphyly of the polytypic D. picumnus. A combination of coalescent and population genetic structure analyses further supported an evolutionary independent status for D. picumnus transfasciatus, but were ambiguous with respect to the statuses of nominate D. picumnus, D. picumnus pallescens, D. picumnus validus, and D. picumnus costaricensis. In contrast, D. picumnus olivaceus and D. platyrostris intermedius were polyphyletic and not genetically structured with respect to D. picumnus pallescens and D. platyrostris platyrostris, respectively. Our results did not support the monophyly of the previously defined ‘Amazonian' and ‘montane' subspecies groups of D. picumnus, further indicating that at least one ‘montane' taxon may actually belong to the ‘Chaco' group, a relationship that highlights a close historical connection between the Andean and Chacoan biotas. When interpreted together with previous morphological studies, our results support the split of the polytypic D. picumnus into at least two species, while keeping the status of D. hoffmannsi and D. platyrostris as distinct species.