Eyebrowed Hemispingus
Formerly treated in Hemispingus but recently found to be part of the Thlypopsis clade. Races can be organized into three groups in two ways: either “superciliaris group” with yellow underparts, “leucogastra group” with white underparts, and single-taxon “urubambae group” again with yellow underparts (no intergrades between groups found); or, as followed here, “chrysophrys group” with yellow eyebrow, “superciliaris group” as above but plus the disjunct urubambae and minus chrysophrys, and the “leucogastra group”. “Leap-frog” plumage pattern (yellow underparts in populations on each side of grey population) and supercilium yellow in far N and white elsewhere are curious circumstances, suggesting that more than one species is involved, but vocally they are very alike. Race leucogastra misspelt in HBW/BirdLife Checklist. Seven subspecies currently recognized.
Taken from: hbw.com.