In 1760 the French zoologist Mathurin Jacques Brisson included a description of the red-capped cardinal in the supplement to his Ornithologie based on a specimen collected in "America".

[2] Although Brisson coined Latin names, these do not conform to the binomial system and are not recognised by the International Commission on Zoological Nomenclature.

[3] When in 1766 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the twelfth edition he added 240 species that had been previously described by Brisson in his Ornithologie.

Linnaeus included a terse description, coined the binomial name Tanagra gularis and cited Brisson's work.

This distinctive taxon was determined a different species, as suggested by the lack of hybridization with P. g. gularis in the limited area of overlap in southern Venezuela.

In pattern the juvenile resemble the adults, but the upperparts are dusky-brown, the head is deep brownish-buff (darker on the cap), the bill is entirely black and the iris is pale, dull creamy-yellow.

The red-capped cardinal has been recorded to breed at least from June to September in northern South America but at Sacha Lodge at the Napo River (Ecuador) an adult was seen feeding a fledgling shiny cowbird (a brood parasite) in late March.

These have a background colour varying between whitish and dull olive and have dense dark brown flecks and blotches, heavier at the blunt end.