Authors:Brian Tilston Smith; Gregory Thom; Leo Joseph; Abstract: Parrots (Order: Psittaciformes) are a diverse clade that is easily distinguishable from other birds. Despite the clear characters that define Psittaciformes (hooked bills, zygodactylous feet, and plumage that is often predominantly green or red), relative morphological uniformity among parrots has made taxonomic classification a fraught endeavor for over a century. Parrot systematics were propelled forward when DNA sequencing data shed insights into higher- and species-level relationships. However, despite these significant advances, major gaps in taxon sampling and uncertainty in relationships remained due to inferring phylogenetic relationships with short fragments of DNA. Recent work using genome-wide molecular markers with nearly complete parrot species-level sampling has brought clarity to many of the remaining outstanding questions on taxonomic relationships. Here, we build on this work by including four additional species to present a taxonomic revision of Psittaciformes better aligned with its evolutionary tree. We infer maximum likelihood and time-calibrated phylogenies for parrots, present accounts for 106 genera, compare how our findings relate to previous work, and highlight future areas of research. The family-group nomenclature we propose reflects deep evolutionary divergences with diagnosable synapomorphies that are commensurate across comparable ranks in psittaciform clades. We erect three new family-group names at the rank of tribe (Brotogerini Smith, Thom, and Joseph, 2024; Neophemini Schodde, Mason, Smith, Thom, and Joseph, 2024; Bolbopsittacini Smith, Thom, and Joseph, 2024). We elevate one tribe to subfamily rank for the cacatuid genus and we restrict usage of the recently introduced tribe Touitini to its type genus . At shallower taxonomic scales, recognition of more rather than fewer genera addresses issues of paraphyly or high discordance in morphological and genomic characters at those levels. We support many reinstatements of older generic names advocated in recent decades, and we further reinstate five valid, available generic names not widely used in recent literature if at all (, , , , ). We advocate the retention of Lesson, 1833, over Wagler, 1832, based on preliminary examination showing substantially more frequent usage of the former. We redraw generic limits in some other cases (e.g., parrotlets and allies) and this includes recognizing fewer genera than recently proposed for the sensu lato ringneck parakeets. Our revised classification of parrots addresses many longstanding taxonomic questions including those that have arisen through the acquisition of genetic data. It provides context for the temporal origins of psittaciform clades and the taxonomic and phenotypic diversification throughout their evolutionary history. We hope that it will be a benchmark guiding further taxonomic study as well as for downstream analyses in many other fields.
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