This taxon is Not Recognised as a species by BirdLife International.
Gymnobucco calvus and G. vernayi (del Hoyo and Collar 2014) were previously lumped as G. calvus following Sibley and Monroe (1990, 1993).
BirdLife International (2016) Species factsheet: Gymnobucco calvus. Downloaded from http://www.birdlife.org on 06/12/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 06/12/2016.