This taxon is Not Recognised as a species by BirdLife International.
L. michahellis and L. armenicus (del Hoyo and Collar 2014) were previously lumped as L. michahellis following a review by the BirdLife Taxonomic Working Group. Prior to that, L. armenicus had been split and L. cachinnans (del Hoyo and Collar 2014) had been lumped with L. michahellis as L. cachinnans following Sibley and Monroe (1990, 1993).
BirdLife International (2016) Species factsheet: Larus michahellis. Downloaded from http://www.birdlife.org on 03/12/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 03/12/2016.