The Straight-billed Hermit
Phaethornis bourcieri inhabits the understory of upland terra-firme forest, being distributed
through most of the Amazon. Currently, two allopatric taxa considered valid and, regarded as
subspecies, are included in P. bourcieri: P. b. bourcieri and P. b. major. Nonetheless, these
taxa have their validity, inter-specific limits, and evolutionary history not fully elucidated.
Here, we used morphological and molecular characters to review the taxonomy and propose a
phylogenetic hypothesis for populations and taxa grouped under Phaethornis bourcieri. Our
results showed that P. bourcieri is part of the straight-billed Hermit clade, along with P.
philippii and P. koepckeae, and that the subspecies major is closer to the latter two species
rather than populations grouped under nominate bourcieri. Our phylogenetic hypotheses
recovered three main reciprocally monophyletic clades under nominate bourcieri separated by
the Negro and Solimões rivers. These clades (along with the distantly related major) are best
treated as valid phylogenetic and biological species, for which only three valid names are
applicable. The diversification of the straight-billed Hermit clade (P. bourcieri, P. philippii,
and P. koepckeae) is centered in the Amazon and appears to be tightly linked with the
formation of the modern Amazon drainage during the Plio-Pleistocene.
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