A new species of Peperomia Ruiz & Pav., P. rivulamans Silverst. (Piperacaeae), is described from the Cauca Valley, Colombia. The new species is saxicolous and inhabits forested creek banks. It differs from all other known peltate-leaved species of Peperomia in the following combination of characters: rhizome creeping, with internodes very short (less than 1 cm); petioles very long (to 22 cm); leaves ovate, white on abaxial surface; inflorescences simple (not paniculate) and axillary; floral bracts mucronate, butterfly-shaped, imbricate at their corners, forming a roof above the fertile rachis, with openings for the ovary and anthers, each opening surrounded by four bracts; ovary turbinate, stigma bifid, apical; and fruits sessile, subclavate, not rostrate. Based on its morphology, the new species is placed in Peperomia subg. Tildenia Miq., but a published study of chloroplast DNA has shown that subgenus Tildenia is polyphyletic.