We describe a new species ofPristimantisfrom the montane forest of the Río Zuñag Ecological Reserve, upper basin of the Pastaza River, Ecuador.Pristimantismalliisp. n.is characterized by a snout-vent length of 11.6–21.3 mm in adult males (n= 12), 22.6–34.3 mm in adult females (n= 8), and is compared morphologically and genetically withPristimantismiktosand with other relevant species ofPristimantis. The new species is characterized by having skin on dorsum and flanks shagreen, distinctive scapular folds, snout broadly rounded in dorsal view, upper eyelid bearing one or two subconical tubercles and some rounded tubercles, dorsum and flanks light brown to brown, with irregular dark brown marks bounded by dirty cream and groin with irregular yellowish marks.