White-bellied Antbird is a terrestrial insectivorous antbird (family Thamnophilidae) found in lowland Neotropical forests from eastern Panama to northeastern Brazil. The Spanish common name is hormiguero ("antbird") ventriblanco (literally "white-bellied"). The generic name is derived from the Greek Myrmeco- ("ant") + -izo ("ambush"). The specific epithet is derived from the Greek longi- ("long") + -pes ("foot"or "leg"). The scientific name is a misnomer - White-bellied Antbird does not consume ants or follow army ant (Eciton burchellii) swarms, nor does it have particularly long legs relative to other terrestrial insectivores. It is a socially monogamous species that exhibits duetting behavior between mates. It builds a cup-shaped nest near the ground with a modal clutch size of two eggs (Austin-Bythell 2013).
White-bellied Antbird is dimorphic and the four currently recognized subspecies are geographically variable in plumage. In general, males have warm rufous upperparts with a black throat, a gray supercilium that extends down the sides of the neck, and a white belly. In contrast, females lack the black throat patch, instead having light cinnamon/brown underparts, and also have black spotting of varying intensity on the wing coverts. Differences in morphology and vocalizations of the four subspecies suggest that White-bellied Antbird may comprise more than one species, although further research on the evolutionary relationships among the subspecies is needed to validate this idea.
White-bellied Antbird possesses a comparatively wide, but also highly disjunct range across northern South America, entirely north of the Amazon, with a small extension of its range into easternmost Panama. A shy species, it can be difficult to observe without the use of a playback. It prefers dense, tangled vegetation at the edges of forest and near clearings and light gaps. Furthermore, it is relatively tolerant of fragmentation, and is more common in second-growth habitats and drier, deciduous forests.