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

Giant hummingbirds (Patagona spp.) are extraordinarily large but nondescript hummingbirds whose taxonomy has been muddled for two centuries. Patagona systematics 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 name gigas (Viellot 1824) and subspecies name peruviana (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 of P. gigas appears 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. The peruviana lectotype 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. Redefining peruviana to 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 name chaski was introduced concomitantly with the definitive discovery of the two Patagona species 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 of peruviana and adoption of chaski, 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.