During an ongoing monograph of Piperaceae from the Ducke Reserve in Manaus, Amazonas, Brazil, two unknown climbing species of Piper were discovered and are here described, illustrated, compared to similar species; an identification key to the climbing species of Piper of Brazil is also provided. Piper naiadense is characterized by pubescent parts with down-curved trichomes, elliptic to lanceolate leaf lamina that have an acute base and acuminate apex and with 4 to 5 pairs of secondary veins arising along the lower half of the midrib, short inflorescences (1.1–1.5 cm long), a pilose rachis, and sessile, crescent-shaped floral bracts. Piper paulobocanum is glabrous except for the pilose abaxial side of the lamina, which are lanceolate to ovate, black-dotted, with an obtuse base and an attenuate apex with 9 to 10 secondary veins arising along the entire midrib, inflorescences that are 2.8–4 cm long, with an apiculum, glabrous rachis, and stipitate, crescent-shaped floral bracts, that are pilose along the margin and on the stalk, and with a keel along the upper side.
