Phaethornis aethopygus is a hermit hummingbird recorded along the Tapajós River in Brazil. The study examined specimens and field records from the river’s eastern bank.
The specimens examined in the study had white margins on the outer tail feathers. The authors also reported plumage differences related to age and sex.
At the eastern-bank localities, it was recorded in terra firme forest, including areas along streams; the paper also mentions records from disturbed sites.
An extinction-risk assessment has not been added yet.