[5] It was later, and for a long time, considered a subspecies of the then warbling antbird Hypocnemis cantator sensu lato.

[3] In the 2007 paper, Isler et al. noted that each might represent a full species but conservatively recommended that they be treated as subspecies pending further investigation.

In addition, they suggest that the westernmost population of implicata probably represents a new subspecies or species that they call taxon novum.

Their flight feathers are rufescent brown with yellowish olive-brown edges and their wing coverts black with white tips.

Subspecies H. s. implicata is the westernmost; it is found between the rios Madeira and Tapajós and its tributary Teles Pires.

The nominate is found from the Tapajos/Teles Pires east to the Rio Xingu and south into north-central Mato Grosso state.

H. s. affinis is found from the Xingu east to the Rio Tocantins and south into eastern Mato Grosso.

The species inhabits the edges of terra firme and várzea evergreen forest, the transition zone between them, and adjacent mature secondary woodland.

[8] The diet and foraging behavior of Spix's warbling antbird are not known in detail, but it feeds primarily on insects and spiders.