[2] It is endemic to Papua New Guinea and only known from the vicinity of its type locality on the southern slope of Mount Sapau in the Torricelli Mountains, West Sepik Province.

The fronts of the thighs and groin have conspicuous series of bright orange spots.

[1] The male advertisement call is a rapid train of 5–7 pulsed, barking notes.

[1] Hylophorbus proekes is known from primary lowland and lower montane rainforests of Mount Sapau at elevations of 450–1,150 m (1,480–3,770 ft) above sea level.

Males call while hidden under leaves, but sometimes also from exposed sites on the ground.