Telmatobius carrillae Morales, 1988, is a riparian frog inhabiting an altitudinal range of 3,680–4,718 m asl in the Central Peruvian Andes. Snout–vent length at metamorphosis is 21.6 mm; minimum size at maturity is 35.3 mm in males and 40.0 mm in females; and maximum size recorded 53.5 mm and 60 mm, respectively. Variation in size is accounted for by pronounced sexual size dimorphism and sex-independent increase in size along an altitudinal gradient (Bergmann cline). Dorsal and ventral color pattern varies considerably from locality to locality rendering this character unreliable for species diagnosis. Most skin features (e.g., width of skin layers, gland size and frequency) showed a considerable range of covariation with ontogenetic stage, sex, and SVL. The absence of serous glands with large granules, a character state shared with Batrachophrynus spp., is confirmed for T. carrillae. However, analysis of the altitudinal ranges of telmatobiine frogs with and without serous glands with large granules suggests that the apparent synapomorphy of Batrachophrynus spp., and T. carrillae may alternatively constitute a response to the ecological demands of high-altitude habitats rather than a phylogenetic signal.