Species limits, patterns of secondary contact and a new species in the Trogon rufus complex (Aves: Trogonidae)

Abstract

Abstract The black-throated trogon, Trogon rufus, is a widespread, polytypic species-complex with a convoluted taxonomic history. Here, we integrated morphological, vocal and genetic datasets, including spectral data and digital quantification of barred plumage, to assess and redefine its species limits according to the foremost species concepts. We suggest the recognition of four named and one new species. Trogon tenellus and T. cupreicauda are divergent across Central and South America without geographic overlap or intermediates. Trogon chrysochloros in the Atlantic Forests of Brazil is phenotypically, genetically and ecologically distinct. In Amazonia, Trogon rufus consists of three phenotypically distinct subspecies intergrading with each other in a ring-like formation around central Amazonian rivers. Trogon rufus rufus in the Guiana Shield, Trogon rufus amazonicus in south-eastern Amazonia and Trogon rufus sulphureus in western Amazonia, with contact across the Lower Amazon and Madeira rivers, likely due to secondary contact between incompletely diverged lineages. The unique combination of song, morphology and mtDNA features of an unnamed, isolated population in the Atlantic Forest of north-eastern Brazil resulted in its description as a new species, known only from the type locality and considered here as Critically Endangered, requiring urgent conservation actions.