Restinga Antwren is a small passerine, described only as recently as 1990 (Gonzaga and Pacheco 1990), and considered to be the only bird species endemic to restinga (an ecosystem associated with Atlantic Rainforest). The species has a very restricted distribution, occurring only in seven municipalities of Rio de Janeiro State, Brazil. Most of its range has been under legal protection since 2011 (Costa do Sol State Park), although the habitat of the antwren is fragmented and under very high anthropogenic pressure. Habitat loss due to real estate development is the main threat to this species. Restinga Antwren is categorized as Critically Endangered at the national level and Endangered in global and regional levels. Because of this, an Action Plan was developed in 2010. Despite the small range of its distribution, the species is locally abundant. Males and females differ in plumage, and are usually observed foraging in pairs. Information on the biology and ecology of Restinga Antwren has been increasing, particularly in the last decade.