Spix's warbling antbird

Spix's warbling antbird is 11 to 12 cm (4.3 to 4.7 in) long and weighs 10 to 14 g (0.35 to 0.49 oz). Adult males of the nominate subspecies 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; their nape and back have black and white streaks. Their rump is rufous. Their flight feathers are rufescent brown with yellowish olive-brown edges and their wing coverts black with white tips. Their tail is rufescent 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, the interscapular patch is small or absent, their nape and back are streaked buff, black, and white, and their wing coverts are olive-brown with pale buff tips. Subspecies H. s. implicata is similar to the nominate but less deeply rufescent and with more muted black and white streaking. Males of H. s. affinis are more heavily marked than those of implicata but females are less heavily marked.