New information on vocalizations of populations of the White-eyed Foliage-gleaner (Automolus leucophthalmus), and analysis of biometric and plumage characters, reveal that it consists of two biological species. One form is restricted to the Pernambuco Center of Endemism in coastal northeastern Brazil and the second occupies much of the remainder of humid Atlantic Forest from Bahia, Brazil south to northeastern Argentina and eastern Paraguay. The northeastern form, although cryptically similar morphologically to other subspecies of Automolus leucophthalmus, is highly differentiated in several vocal characters. The vocal difference between the two groups exceeds that between other accepted species pairs within the genus. Reciprocal tape-playback experiments offer supporting evidence that vocal differences within the White-eyed Foliage-gleaner complex are sufficient to act as isolating mechanisms in the event of secondary contact between the two groups. The northeastern form is shown to have vocal and morphological similarities to the Para Foliage-gleaner (Automolus paraensis) of southeastern Amazonian Brazil, supporting hypothesized Amazonian origins of the leucophthalmus complex, as well as a sister relationship with the Automolus infuscatus/paraensis complex.