Taxonomic status of Cyanoramphus parakeets on the Auckland Islands and implications for the validity of the orange-fronted parakeet as a discrete species

Cyanoramphus parakeets are a key biogeographic element of the Pacific. Many of these parakeets are, however, endangered, with ongoing conservation management hampered by the unresolved taxonomic status of some populations. We used modern and ancient DNA (mitochondrial DNA control region) to assess the taxonomy of the Auckland Islands populations of red-crowned (Cyanoramphus novaezelandiae novaezelandiae) and yellow-crowned (Cyanoramphus auriceps) parakeets. Our analyses show that both red-crowned and yellow-crowned parakeets on the Auckland Islands are nested within the mainland New Zealand diversity of the two species. However, we also found an orange-fronted parakeet (Cyanoramphus malherbi) mitochondrial DNA lineage within the genome of both of these species in the Auckland Islands population. Further sampling of historic orange-fronted parakeet museum skins showed that the orange-fronted morphotype is paraphyletic with respect to mitochondrial haplotype, which is probably caused by hybridisation or incomplete lineage sorting. In light of this, we review and critically assess the taxonomic history of the orange-fronted parakeet, and address whether the species was historically present on the Auckland Islands.