The Norfolk Island Green Parrot and New Caledonian Red-crowned Parakeet are distinct species

Abstract

The Norfolk Island Green Parrot and New Caledonian Red-crowned Parakeet were first described in the middle of the last century as subspecies of the widespread New Zealand Red-crowned Parakeet (C. novaezelandiae). Molecular phylogenetic analyses of all extant taxa of Cyanoramphus, except the Kermadec Island Parakeet (C. novaezelandiae cyanurus), reveal that the Norfolk Island Green Parrot, previously C. n. cooki, and New Caledonian Red-crowned Parakeet, previously C. n. saisetti, are highly divergent from all other members of the genus. We therefore elevate them to full species status as C. cooki and C. saisetti respectively. In our DNA sequencing study, two highly distinct, statistically well supported monophyletic clades were identified for both taxa under maximum likelihood, maximum parsimony and minimum evolution analyses. Both taxa are well separated from the C. novaezelandiae clade. The New Caledonian taxon is basal and may be the most ancient of all extant Cyanoramphus species. Levels of uncorrected percentage sequence divergences among mitochondrial (mtDNA) control region DNA sequences ranged from 7.80 to 9.55% between the New Caledonian Red-crowned Parakeet and other recognised congeneric species. The corresponding sequence divergence for the Norfolk Island Green Parrot from other Cyanoramphus species was 3.18—6.44%. Interspecific comparisons of Cyanoramphus species normally range from 2.03 to 7.93% (the latter two ranges do not include comparisons with the New Caledonian Redcrowned Parakeet). The mtDNA sequence data of both Norfolk Island and New Caledonian taxa fulfil criteria for their designation as species under the Phylogenetic Species Concept.