The open vegetation corridor of South America is a region dominated by savanna biomes. It contains forests, i.e. riverine forests, that may act as corridors for rainforest specialist between the open vegetation corridor and its neighboring biomes, the Amazonian and Atlantic forests. A prediction for this scenario is that populations of rainforest specialists in the open vegetation corridor and in the forested biomes show no significant genetic divergence. We addressed this hypothesis by studying plumage and genetic variation of the Planalto woodcreeper Dendrocolaptes platyrostris Spix (1824) (Aves: Furnariidae), a forest specialist that occurs in both the open habitat and in the Atlantic forest. Our questions are: (1) is there any evidence of genetic continuity between populations of the open habitat and the Atlantic forest? and (2) is plumage variation congruent with patterns of neutral genetic structure or with ecological factors related to habitat type? We used cytochrome b and mtDNA control region sequences to show that D. platyrostris is monophyletic and that presents substantial intraspecific differentiation. We found two areas of plumage stability: one associated to Cerrado and the other associated to southern Atlantic Forest. Multiple Mantel tests showed that most of the plumage variation followed transition of habitats but not phylogeographic gaps, suggesting that selection may be related to the evolution of the species plumage. Results were not compatible with the idea that forest specialist in the open vegetation corridor and in the Atlantic forest are linked at the population level because birds from each region were not part of the same genetic unit. Divergence in the presence of gene flow across the ecotone between both regions might explain our results. Also, our findings indicate that the southern Atlantic forest may have been significantly affected by Pleistocene climatic alteration, but that those events did not cause local extinction of most taxa, as occurred in other regions of the globe where forests were significantly affected by global glaciations. Finally, our results neither supported subspecies nor regions of stability of plumage as species.