[2] It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, and Suriname.

[3] The blackish antbird was described by the German ornithologists Jean Cabanis and Ferdinand Heine in 1860 and given the binomial name Percnostola nigrescens.

Females have rufous-tinged olive-gray crown, upperparts, and wings with a white interscapular patch.

The subspecies are found thus:[9][10][11][12][13] The blackish antbird inhabits a variety of densely vegetated but somewhat open landscapes.

These include the edges of terra firme, várzea, and transitional evergreen forest and gaps within them.

[9] The blackish antbird's diet has not been detailed but is known to include a variety of insects and probably also spiders.

Single birds, pairs, and family groups usually forage on the ground or within about 5 m (16 ft) of it though occasionally higher.

It seldom joins mixed-species feeding flocks; it only rarely attends army ant swarms and spends little time with them.

Male blackish antbirds of the nominate subspecies sing "a single low 'wup' followed by short rattle of variable length...that usually becomes less intense".

The "[p]reference of all races for second-growth and edge habitats renders them less vulnerable to disturbance than are most antbirds".