Molecular systematics of two enigmatic genera Psittacella and Pezoporus illuminate the ecological radiation of Australo-Papuan parrots (Aves: Psittaciformes).

The platycercine parrots of Australia, usually recognized as the Platycercinae or Platycercini, are the broad-tailed parrots and their allies typified by the rosellas Platycercus spp. Debate concerning their circumscription has most recently centerd on the position of four genera, Neophema, Neopsephotus, Pezoporus and Psittacella, the last two having never been adequately included in sequence-based analyses. We use broad taxon sampling, mitochondrial and nuclear DNA sequence data from seven independent loci (two linked mitochondrial loci and six nuclear loci), and both gene tree and species tree approaches to reconstruct phylogenies and so determine the systematic placement all four genera. Analyses of two data sets, one of 48 taxa and five loci and one of 27 taxa and the same five plus three additional loci produced broadly congruent and consistently well-resolved phylogenies. We reject placement of any of these four genera within core platycercines. Pezoporus is closely allied to Neophema and Neopsephotus. These three genera are the likely sister group to core platycercines and we advocate their recognition as a subfamily. Psittacella is the sole extant representative of a lineage that branched very early in the history of Australo-Papuan parrot fauna and is not closely related to any of the mostly south-east Asian and Indonesian psittaculine taxa with which it is more often linked. We present a revised view of the extraordinary phylogenetic, phenotypic and ecological diversity that is the adaptive radiation of Australo-Papuan parrots. Finally, our analyses highlight the likely paraphyly of Mayr's (2008) Loricoloriinae.