Vermilion Flycatcher (Pyrocephalus rubinus) is a widespread species, found from S USA south to N Argentina and on the Galápagos Archipelago. Differences in morphology, plumage, song and migratory habits over its range have led to the recognition of 12 or 13 subspecies, some of which are poorly delineated while others have been elevated to species level by various authors. A molecular phylogenetic analysis confirms that Vermilion Flycatcher is likely to comprise at least four species#R. The new molecular data together with its distinct song, exclusive song-recognition behaviour, phenology and isolated breeding range suggest that austral migrant taxon rubinus is probably a separate species. Similarly, morphology and behavioural evidence, combined with mitochondrial and nuclear genetic data, suggest that Galápagos taxa dubius (endemic to San Cristóbal) and nanus (occurring elsewhere in the Galápagos Archipelago), which are sometimes treated as one or two separate species, do indeed both deserve full species status#R. This has implications for conservation. Taxon dubius, once fairly common, was last seen in 1987#R and is now presumed extinct#R#R: this would constitute the first documented avian extinction on the Galápagos Archipelago. Taxon nanus was also formerly quite common, but is now uncommon to rare and extirpated from some islands#R#R; if elevated to species level it would undoubtedly be listed as seriously threatened. Conservation measures are urgently required to preserve considerable genetic diversity within nanus populations, while research is needed to determine whether (as seems probable) nanus itself comprises more than one species#R.