A poorly researched genus, the alliance has been recognised as a single species treatment (Schodde, 1975) and later two species or provisionally three separate species.[2]Birds of the World: Recommended English Names lists the following three species:[3]
Del Hoyo, J.; Elliot, A. & Christie D. (editors). (2006). Handbook of the Birds of the World. Volume 12: Picathartes to Tits and Chickadees. Lynx Edicions. ISBN978-84-96553-42-2