Kielmeyera ferruginosa, a new species of Calophyllaceae from the Atlantic Forest of southern Bahia, is here described and illustrated. The species is critically endangered and can be easily distinguished from other Kielmeyera species by the rusty coloration of the trunk and branches, orange-colored latex, and the occurrence in flooded areas. It differs from the other species of the section Prolifera by the leaves with secondary veins relatively more distant from each other and prominent on the abaxial surface. Diagnostic characters and the state of conservation of the new species are discussed, and an identification key for K. ferruginosa and related species from series Rupestres and Neglectae is provided.