Novelties in Rapatea (Rapateaceae) from Colombia

Rapatea isanae, from the upper Isana [Içana] river, Guianía Department, Colombia, is described and illustrated, and its morphological relationships with allied species are discussed. This taxon is remarkable for Rapatea in its small stature (15-30 cm tall) and leaves, and it is only the second species with white petals in a genus that otherwise has only yellow petals. It is most closely R. spruceana, with the base of the leaf blade gradually tapering from the intergrading into the petiole, and the bractlet of the spikelet and sepal shape. However, this new species differs from R. spruceana in its shorter size, sparse verrucose on the lower surface, the length of the attenuate portion of the involucral bracts, and the shape and color of the petals. It also has similarities to R. longipes and R. modesta in its ventricose sheath-leaf, inflorescence shape, and bractlets equal in length. A previously described species from Colombia is restablished (i.e., R. modesta), and one variety is elevated to the rank of species (i.e., R. paludosa var. sessiliflora to R. sessiliflora). An updated key to the all twenty five species of Rapatea, and an abstract in Kuripaco are also provided.