Until the early 2000s, White-masked Antbird was known from the unique holotype collected in what is now Peru, but the species had been speculated to be a hybrid because of the lack of subsequent sightings in the intervening half century. Its rediscovery in the department of Loreto, and subsequent records in Amazonas, all at localities in northeast Peru north of the Marañón, has revealed White-masked Antbird to be a highly distinctive and obligate ant-following antbird (Thamnophilidae). Its plumage is largely deep rufous with a black head and white mask. White-masked Antbird inhabits the understory of low-elevation forest, both in white-sand varillales and hilly terra firme on poor soils. Due to its small range, White-masked Antbird currently is listed as Near Threatened.