Hymenolobium discolor W. Rodrigues & N. Mattos, nova espécie de Leguminosae da Amazônia.The authors describe the new amazonian species, Hymenolobium discolor W. Rodrigues & N. Mattos, closely related to H. complicatum Ducke, from which it differs mainly by the discolor leaves, the smaller size of the floral pieces, as too by the ovary densely sericeous.