[3] The white-shouldered antbird was described and illustrated by the German naturalist Johann Baptist von Spix in 1825 and given the binomial name Thamnophilus melanoceps.

[5] A year later the same authors determined that by the principle of priority the older genus Akletos, which had been introduced by the Polish ornithologist Andrzej Dunajewski in 1948, was proper.

Adult males are mostly black with a small white patch on their shoulder that is usually visible only in flight.

[8][9][10][11][12][excessive citations] The white-shouldered antbird is a bird of the western Amazon Basin.

It is found from Meta Department in south-central Colombia south through eastern Ecuador into northeastern and east-central Peru as far as northern Ucayali Department and east into western Brazil as far as the Japurá and Juruá rivers.

It mostly favors the shrubby vine-tangled areas immediately adjoining rivers and to a lesser extent similar edges of forest away from water.

It typically forages singly, in pairs, or in family groups in dense vegetation, mostly on the ground and within about 5 m (16 ft) above it.

[8][9][10][11][excessive citations] The white-shouldered antbird's breeding season has not been defined but appears to span July to February in Ecuador.