Complex sentence: For many years the genus "Ara" contained additional species but three genera were split out from the genus, "Orthopsittaca", "Primolius", and "Diopsittaca".
Split into simpler sentences: For many years the genus "Ara" contained a number of other species. Three genera have been split out from the genus, "Orthopsittaca", "Primolius", and "Diopsittaca".