We describe a new species of Pristimantis from a cloud forest at 2450–2800 m in the Cordillera Oriental in southern Ecuador (Zamora Chinchipe). The new species has a maximum snout–vent length of 17.9 mm (average SVL of 21 males  =  12.3 mm ± 1.2, and of 19 females  =  15.9 mm ± 1.3). This new species is the second smallest frog from Ecuador and smallest Pristimantis. Morphologically and phylogenetically, the new species is similar to P. caeruleonotus and P. colodactylus. It is distinguished from them and its congeners by its size, tuberculation, a distinct color pattern consisting of tan blotches on dorsum, spots on a brown venter, minute brown spots on anterior and posterior surfaces of the thighs, and other morphological features. Determination of small body size in frogs is discussed and meristic data of 40 minute frogs are compiled.