[3] The species' specific epithet honors Arthur A. Allen, who collected the type specimen in 1911 and later founded the Cornell Lab of Ornithology.

[4][5] Grallaria antpittas are a "wonderful group of plump and round antbirds whose feathers are often fluffed up...they have stout bills [and] very short tails".

Adults of the nominate subspecies have a light olive brown forecrown and a slate gray crown and nape with thin blackish edges on the feathers.

Both subspecies have a dark brown iris, a black bill, and vinaceous gray legs and feet.

Subspecies G. a. andaquiensis is found in the upper Magdalena River Valley in Colombia and on both slopes of the Andes in Ecuador as far south as Cotopaxi and Napo provinces.

The species inhabits the understory of humid montane forest, where it favors dense undergrowth in ravines and steep slopes.

[5] The moustached antpitta's breeding season has not been detailed but includes September to November in Colombia and March in Ecuador.

Its nest is a bulky cup made of dead leaves, green mosses, rootlets, and other small fibers, placed in an epiphyte or on a branch.