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| South Georgia Gentoo Penguins Pygoscelis poncetii Tyler, Bonfitto, Clucas, Reddy & Younger, 2020 DOI: 10.1002/ece3.6973 Photo by Gemma Clucas |
Abstract
Gentoo penguins (Pygoscelis papua) are found across the Southern Ocean with a circumpolar distribution and notable genetic and morphological variation across their geographic range. Whether this geographic variation represents species‐level diversity has yet to be investigated in an integrative taxonomic framework. Here, we show that four distinct populations of gentoo penguins (Iles Kerguelen, Falkland Islands, South Georgia, and South Shetlands/Western Antarctic Peninsula) are genetically and morphologically distinct from one another. We present here a revised taxonomic treatment including formal nomenclatural changes. We suggest the designation of four species of gentoo penguin: Pygoscelis papua in the Falkland Islands, P. ellsworthi in the South Shetland Islands/Western Antarctic Peninsula, P. taeniata in Iles Kerguelen, and a new gentoo species P. poncetii, described herein, in South Georgia. These findings of cryptic diversity add to many other such findings across the avian tree of life in recent years. Our results further highlight the importance of reassessing species boundaries as methodological advances are made, particularly for taxa of conservation concern. We recommend reassessment by the IUCN of each species, particularly P. taeniata and P. poncetii, which both show evidence of decline.
Keywords: Antarctica, integrative taxonomy, new species, Pygoscelis, Southern Ocean
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| South Georgia Gentoo penguins (Pygoscelis poncetii) live in more northerly habitats where conditions are milder, than their Southern Gentoo cousins, which live on the Antarctic ice. Photo by Gemma Clucas |
Pygoscelis poncetii sp. nov.
Common Name. South Georgia gentoo penguin.
Etymology. Pygoscelis poncetii is named after Sally Poncet, whose body of work has significantly influenced the field of polar biology, particularly in relation to South Georgia.
Diagnosis. Morphologically, P. poncetii can be differentiated from all other species of gentoo by its manus length (mean length = 130.49 mm), being significantly smaller than P. papua (mean length = 135.08 mm, p = .0292) and significantly larger than both P. ellsworthi and P. taeniata (mean lengths = 115.38 mm and 125.27 mm, p < .0001 and p = .0232, respectively). Radius length differentiates P. poncetii (mean length = 52.68 mm) from the larger P. papua (mean length = 58.11 mm, p = .0003) and smaller P. ellsworthi (mean length = 48.90 mm, p = .0039). Genetic comparative techniques (Pairwise FST, heterozygosity, clustering methods) found significant differences among all four species of gentoo penguin with the maximum likelihood phylogeny resolving each species as 100% supported. There are no discernible differences in plumage patterns among the four species.
CONCLUDING REMARKS:
In this paper, we highlight hidden biodiversity within the species P. papua using genetic and morphometric methods, in keeping with recent assessments of hidden species diversity in birds. Our results clearly support the division of gentoo penguins into at least four species. We name a new species of gentoo, P. poncetii, and recommend elevation of three subspecies to species level (P. taeniata, P. papua, and P. ellsworthi). Our results show the importance of reassessing species boundaries as methodological advances are made. These findings have implications for the threat status of these species, and we urge that this diversity is considered in conservation planning for the Southern Ocean.
Joshua Tyler, Matthew T. Bonfitto, Gemma V. Clucas, Sushma Reddy and Jane L. Younger. 2020. Morphometric and Genetic Evidence for Four Species of Gentoo Penguin. Ecology and Evolution. DOI: 10.1002/ece3.6973
