The spotted bamboowren is 13.5 cm (5.3 in) long. Males weigh 10.5 to 13 g (0.37 to 0.46 oz), and one specimen thought to be a female weighed 11.5 g (0.41 oz). The adult male's head and upper back are gray, and the lower back brownish. The throat and upper breast are whitish to buff, merging to buff on the lower breast and belly. The back, wings, and belly are sprinkled with small white, brown, or black spots. The adult female is similar, but the top of the head and upper back are brown, and the upper breast buffy.
The spotted bamboowren is endemic to the Atlantic Forest biome of Brazil and Argentina. Its range extends from southeastern Minas Gerais and western Espírito Santo through Rio Grande do Sul in Brazil into Argentina's northern Misiones Province. It might also occur in southeastern Paraguay, though the South American Classification Committee of the American Ornithological Society (AOS) has not confirmed that.
As its name implies, the spotted bamboowren is usually found in bamboo, typically at the edge of dense forest, but also in tangles of vines and other dense foliage. In the northern part of its range it is found from 600 to 1,000 m (2,000 to 3,300 ft) elevation and in the south from 300 m (980 ft) up.
The spotted bamboowren typically feeds around 2 m (6.6 ft) above ground in bamboo and branches but up to 7 m (23 ft) in vine tangles. It occasionally forages on the ground. Its principle prey is insects and insect larvae.
The spotted bamboowren's breeding phenology has not been studied.
The IUCN has assessed the spotted bamboowren as Near Threatened. Its range is restricted to the southern Atlantic Forest, a biome that has undergone extensive clearing for agriculture and human settlement. Its population is unknown but is believed to be decreasing. It does, however, inhabit a few protected areas.
