An Integrative Approach to Species-level Systematics Reveals the Depth of Diversification in an Andean Thamnophilid, the Long-tailed Antbird

The geographic range of the Long-tailed Antbird (Drymophila caudata) extends from the Paria Mountains of Venezuela south through the Andes to northern Bolivia, a geographic and elevational distribution unique in the antbirds (Thamnophilidae). Plumage variation among most populations is not obvious, and although eight subspecies have been described, half have been synonymized. We took a multidimensional approach to reexamining the taxonomy of the complex. We identified lineages by evaluating divergence in mtDNA, and defined study groups within them to take into account previously described plumage differences. We then assessed the taxonomic status of principal lineages and study groups by comparing vocal differences among them to established taxonomic “yardsticks” for thamnophilid antbirds. Finally, we related taxa to the ecology of the regions in which they occur. The outcomes revealed substantial diversification, sufficient for recognition of four species, three restricted to the north and one widespread along the main body of the Andes extending from northwestern Colombia south to Bolivia. Speciation in Andean Drymophila antbirds is partially associated with elevational and environmental divergence. The results provide valuable inputs to mapping and understanding avian evolution in the Andes and demonstrate the value of a multifaceted approach in solving taxonomic problems.