A Cryptic New Species of Thrush (Turdidae: Turdus) from Western Amazonia

Abstract. The taxonomy of Hauxwell's Thrush (Turdus hauxwelli) with respect to its relationship to the Cocoa Thrush (Turdus fumigatus) has been complicated. A confounding factor has been the morphological variation reported within T. hauxwelli and the apparent geographic overlap of the two taxa. Recent evidence shows that some of these factors may be explained by the existence of a cryptic, syntopic species, very similar in plumage to T. hauxwelli. The new species differs in minor plumage characters, in soft-part colors, and (especially) in voice. On the basis of vocal and molecular data, we propose that the new thrush is not particularly closely related to the T. fumigatus/hauxwelli complex but rather is the western Amazonian member of the Spectacled Thrush (T. nudigenis) complex. Our molecular phylogeny suggests that the new species is sister to the Unicolored Thrush (T. haplochrous) and also that the Ecuadorian Thrush (T. maculirostris) should be considered a species separate from the Spectacled Thrush...