Pygoscelis adeliae
Pygoscelis antarctica
Pygoscelis papua
†Pygoscelis tyreei (fossil)
†Pygoscelis calderensis (fossil)
†Pygoscelis grandis (fossil)
The genus Pygoscelis ("rump-legged") contains three living species of penguins collectively known as "brush-tailed penguins".[2]
Mitochondrial and nuclear DNA evidence suggests the genus split from other penguins around 38 million years ago, about 2 million years after the ancestors of the genus Aptenodytes. In turn, the Adelie penguins split off from the other members of the genus around 19 million years ago.[3]
A 2020 study found that the gentoo penguin may actually comprise a species complex of 4 similar but genetically distinct species: the northern gentoo penguin (P. papua), the southern gentoo penguin (P. ellsworthi), the eastern gentoo penguin (P. taeniata), and the newly-described South Georgia gentoo penguin (P. poncetii).[4][5] However, in 2021 the International Ornithological Congress recognized these as being subspecies of P. papua.[6]
A study has estimated that there are about 3.79 million pairs of Adélie, 387,000 pairs of gentoo, and 8 million pairs of chinstrap penguins in their particular areas, making up 90% of Antarctic avian biomass (Black, C. E. 2016). [7]