Rondônia Warbling-Antbird

The Rondonia warbling antbird is 11 to 12 cm (4.3 to 4.7 in) long and weighs 11 to 15 g (0.39 to 0.53 oz). Adult males have a black crown with a white central streak and a white supercilium on an otherwise black and white speckled face. Their upperparts are olive-gray with a white patch between the scapulars; the center of the patch has black and white speckles. Their rump is rufous. Their flight feathers are brown with yellowish olive-brown edges and their wing coverts black with white tips. Their tail is brown with pale buff tips to the feathers. Their throat is very pale gray. Their breast and sides are spotted with black and white, their belly's center is white, and their flanks and undertail coverts are rufous. Females have the same pattern but different colors than males. Their crown is streaked with pale buff, their back is lightly streaked pale ochraceous-brown, the interscapular patch is small or absent, and their wing coverts are olive-brown with pale buff tips.

Its range extends from the rio Madeira to rio Roosevelt (in the western Brazilian states of Rondônia and Mato Grosso and the eastern Bolivian departments of Beni and Santa Cruz). It primarily inhabits terra firme evergreen forest, and also várzea, adjacent mature secondary woodland, and the ecotone between forest and savannah. It mostly occurs in dense understorey vegetation at forest edges and within the forest at gaps caused by fallen trees. In elevation it ranges as high as 1,300 m (4,300 ft).

The Rondonia warbling antbird's diet and foraging behavior are not known, but are assumed to be very similar to those of its previous "parent" Hypocnemis cantator.