This taxon is Not Recognised as a species by BirdLife International.
Ramphastos vitellinus, R. culminatus, R. citrolaemus and R. ariel (del Hoyo and Collar 2014) were previously lumped as R. vitellinus following SACC (2006) and a review by the BirdLife Taxonomic Working Group, and before then were split as R. vitellinus, R. culminatus and R. citreolaemus following Sibley and Monroe (1990, 1993).
BirdLife International (2016) Species factsheet: Ramphastos vitellinus. Downloaded from http://www.birdlife.org on 05/12/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 05/12/2016.