In 1951 American ornithologist Rodolphe Meyer de Schauensee did what many dream of: he described a new bird species: the Argus Bare-eye (Phlegopsis barringeri). This new species of antbird was based on one specimen, collected on the Rio Rumiyaco in Colombia.
Later, Willis (1979) suggested that the specimen might be a hybrid between Black-spotted Bare-eye (P. nigromaculata) and Red-winged Bare-eye (P. erythroptera). These two species overlap from eastern Colombia to northern Bolivia.
This suggestion was tested by Graves (1992), who reexamined the original specimen and compared it to the two putative parental species. His conclusion: it’s a hybrid!
Graves, G. (1992). Diagnosis of a hybrid antbird (Phlegopsis nigromaculata× Phlegopsis erythroptera) and the rarity of hybridization among suboscines. Proceedings of the Biological Society of Washington 105, 838-840.
Willis, E. O. (1979). Comportamento e ecologia da maede-taoca, Phlegopsis nigromaculata (d’Orbigny & Lafresnaye)(Aves, Formicariidae). Rev. Brasil Biol 39, 117-159.
These papers have been added to the Thamnophilidae page. A special thank you to Mort Isler for directing me to this case.