Mosesia ovalis n. sp. (Digenea: Phaneropsolidae) is described based on one specimen found in the intestine of a green manakin (Pipridae: Xenopipo holochlora Sclater, 1888) collected in the Cordillera Azul National Park, Peru. Mosesia ovalis n. sp. differs from the morphologically similar species Mosesia mosesi (Travassos, 1921) and Mosesia chordeilesia McMullen, 1936 in its body shape and proportions, the shape of its testes, and the extent of its ceca. The morphological description of the new species, and notes clarifying some morphological features of Mosesia mosesi, the type species of Mosesia, are provided.