Males have two very long white and black tail feathers, glossy blue head and neck, small beak and a black body.

Females have fewer blue feathers on their head as well as shorter tails.

Until 1930, Barnes's astrapia (and all the other hybrid birds-of-paradise) were thought to be species and were named as such.

Barnes's astrapia was named Astrarchia barnesi by Iredale in 1948, under the presumption that it is a species.

[1] Barnes's astrapia lives in the montane forest of Papua New Guinea, where the ranges of the parent species overlap on a small part of the Hagen Range and Mount Giluwe, usually at 2,300–2,600 m asl.