Integrative taxonomy reveals hidden diversity in the Catharus fuscater (Passeriformes: Turdidae) complex in Central and South America

We assembled datasets of genetic (genomic ultraconserved elements [UCEs], mtDNA) and phenotypic (morphology, voice) characters to address species limits and taxonomy in the slaty-backed nightingale-thrush Catharus fuscater (Passeriformes: Turdidae), a polytypic complex of songbirds with a broad montane distribution in Central and South America. We identified 10 allopatric populations that have been evolving independently for multiple glacial cycles. Genetic structure is broadly correlated with divergence in phenotypic characters, including plumage colour, iris colour, maxilla (bill) colour, and the acoustic structure of vocalizations (calls and songs). We propose an integrative taxonomic revision that recognizes seven species in the complex, including a newly described species from eastern Panama, and four subspecies, of which two are newly described.