Amanoa marapiensis, a new species endemic to Pará State, Brazil, is described, illustrated, and discussed. It is morphologically similar to A. steyermarkii from Venezuela, but it differs in its more congested inflorescence, chartaceous leaves with entire margins, slightly revolute near the base, and the network of shiny, translucent “islands” and isolated punctations that are visible with a loupe, especially on the abaxial surface, as well as the scarcely evident secondary veins. The species was collected in an area of difficult access, by helicopter, as part of the RADAMBRASIL Project, at an altitude of 350 m. A revised key to the Neotropical species of Amanoa is presented.