Taxonomy, nomenclature, and identification of the giant hummingbirds (Patagona spp.) (Aves: Trochilidae)

Abstract

Giant hummingbirds (Patagonaspp.) are extraordinarily large but nondescript hummingbirds whose taxonomy has been muddled for two centuries.Patagonasystematics were redefined in a study of migration, physiology, and genetics by Williamson et al. (2024), revealing two species with divergent genomes and seasonal range overlap: Southern Giant Hummingbird (P. gigas) and Northern Giant Hummingbird (P. chaski). However, the taxonomy and nomenclature of the genus need to be reconsidered in light of its newly-clarified biology and species limits. The species namegigas(Viellot 1824) and subspecies nameperuviana(Boucard 1893) were both described based on multiple syntypes. Here, we designate a lectotype for each name and we critically consider the identity and usage of each. The lectotype ofP. gigasappears to be a Southern Giant Hummingbird, albeit from unknown provenance, and the historic and ongoing usage of this name has been restricted to that entity. Theperuvianalectotype appears to be a Northern Giant Hummingbird, but usage of the name throughout history has involved misdiagnosis and misapplication to entities that comprise variable mixtures of the two giant hummingbird species. Redefiningperuvianato match Northern Giant Hummingbird would shift the entity to which this name has referred, sowing confusion due to its non-universal meaning. By contrast, the species namechaskiwas introduced concomitantly with the definitive discovery of the twoPatagonaspecies and their taxonomic limits, morphology, physiology, migration, genetics, and year-round distributions. The Principle of Priority (Art. 23) of the International Code of Zoological Nomenclature provides a mechanism to suppress problematic senior synonyms. We invoke Art. 23.9.3 and urge suppression ofperuvianaand adoption ofchaski, the only name that applies specifically and uniquely to Northern Giant Hummingbird. Lastly, we report misidentified specimens in major museum collections, and we provide comprehensive information on species identification and seasonal ranges for these cryptic species.