Relatively small antbird with heavily streaked upperparts, spotted chest, and rusty lower back and belly. Inhabits the understory of humid forest, seasonally flooded forest, and tall second growth. Forages in dense vine tangles, and sometimes accompanies mixed-species flocks or attends army-ant swarms. The song is a descending series of 9-10 clear notes ending abruptly. Similar to Rondonia Warbling-Antbird, but Spix's Warbling-Antbird has a black (not gray) mantle and a more heavily streaked breast, while the back of females is less streaked and duller brown.