The unusual scientific name of Brown-backed Antwren honors the Scandinavian ornithologist Jon Fjeldså. This species is highly restricted in range, being confined to southeastern Ecuador and extreme north-central Peru, where it is found in lowland evergreen forest on nutrient-poor soils, both on terra firme and, to a lesser extent, in seasonally flooded areas. Our provisional knowledge suggests that it prefers areas with a high density of palms in the understory. Like other species of Epinecrophylla, the Brown-backed Antwren is a dead-leaf specialist and forages in singles, pairs or as small family groups, but usually within mixed-species flocks, which are typically led by a species of Thamnomanes antshrike. Brown-backed Antwren is a member of the Epinecrophylla haematonota complex, all of which formerly were included in a single broad species, "Stipple-throated Antwren". The males of all members of this group have black and white spots, or stippling, on the throat. The males of most species in this group have a rufous back; the two exceptions are Brown-backed Antwren and Foothill Antwren (Epinecrophylla spodionota), of the lower slopes of the Andes. Brown-backed Antwren apparently is most closely related, however, to Rufous-backed Antwren (Epinecrophylla haematonota), which geographically replaces it in the lowlands of eastern Peru and western Brazil.