Potamites flavogularis sp. nov. is described from the Napo and Tungurahua Provinces around 1800 m elevation in eastern Ecuador. The new species is closely related, sibling, and sympatric to Potamites cochranae to which it has been previously confused. It is characterized by the absence of isolated basal flounces of spines and presence of calcareous spinules on flounces of the hemipenis, a short (1,30–1,41 times SVL) and slightly compressed tail without tubercles, tympanum slight-ly recessed, subimbricate ventral scales, lateral body scales lacking conspicuous enlarged tubercles, four longitudinal rows of dorsal tubercles, 6 transverse series of ventral scales, absence of intercalated scales along sides of tail, and absence of tubercles on sides of neck and gular regions. Like their congeners, the new species was found close to vegetation surround-ing streams in primary and secondary forests.