Telmatobius gigas Vellard 1969

Large, low head, rounded in profile, with a moderately long snout that is slightly subacuminate. Nares are dorsolateral and not protuberant, positioned either halfway between eye and snout tip, or closer to eyes. Eyes are moderately large and oriented anteriorly. Canthus rostralis is not very distinct. Loreal region is concave. Lips are thick and flared. Vomerine teeth are located between the choanae, with each ridge bearing three small, pointed teeth. Tympanum is lacking. Supratympanic fold is present but short and weakly defined. Postcommissural gland is absent. Fingers are not webbed. Fingertips are slightly enlarged. Finger II has slight lateral fringe. Hindlimbs are relatively short and toes are webbed. Skin is rugose and bears small rounded and flattened pustules. Ventral discoidal fold present. Posterior thigh skin slightly loose. Males have nuptial excrescences consisting of thick pads of small black spicules on the inner surface of Finger I. One male had small keratinized spicules on the chest (de la Riva 2002).Dorsal surfaces are olive-green with tiny dark spots on small green pustules (two females), or brown with dark irregular lichenous blotching (males). Flanks shade to beige with pale beige-yellowish pustules. Venter is cream with small gray dots (de la Riva 2002).Tadpoles are the largest recorded for any species of Telmatobius, with the biggest specimen at 109 mm in stage 38. The larval body is oval and depressed. The snout is rounded, with small nostrils that are not raised are located slightly closer to the eye than to the snout tip. The spiracle is sinistral and the vent is dextral. The mouth is anteroventral. The oral disc has a wide rostral gap. Oral papillae are large; ventral marginal papillae are large and conical and present in multiple rows. Beaks are finely serrated. The dorsal and ventral tailfins are roughly equal in height; the dorsal fin does not extend onto the body. The tail tip is rounded (de la Riva 2002).Telmatobius gigas females differ from sympatric T. marmoratus females in having larger size (T. gigas maximum female SVL is 109 mm, vs. 69 mm in T. “marmoratus” (Vellard, 1953), more robust bodies and shorter hindlimbs, mottled ventral coloration (cream with gray mottling in T. gigas vs. uniformly cream in T. “marmoratus”), dorsal coloration (olive-green with tiny dark spots in female T. gigas vs. gray to brown with or without pattern in female T. "marmoratus") and eyes placed frontally (vs. eyes frontolateral in T. "marmoratus"). Telmatobius gigas males have longer snouts and more flared lips than sympatric T. "marmoratus". In addition, Telmatobius gigas can be distinguished from T. culeus (the other giant form of Telmatobius) by a greater head height, larger eyes, less pointed snout, lack of baggy skin on flanks and limbs, and smaller maximum size (109 mm SVL in female T. gigas vs. 134 mm SVL in female T. culeus) (de la Riva 2002).This species was described in 1966 (as a giant-sized subspecies of Telmatobius marmoratus) by Vellard, but Vellard's holotype has not been found in museum collections (de la Riva 2002). A neotype was designated in 1998 from specimens collected at the original type locality (de la Riva 2002).

Endemic to Bolivia. Known only from the type locality in the central altiplano of the Bolivian Andes: the canyon of Río Huayllamarca, Cordillera Huayllamnarca, Carangas Province, Oruro Department, at 3,965 m asl. Found in high-elevation streams running through puna grassland habitat (Stuart et al. 2008). Probably present in other suitable sections of the Río Huayllamarca (the parts with stones rather than sandy bottoms) and other streams within the Serranía de Huayllamarca mountain range (de la Riva 2002).

The Río Huayllamarca flows down through a small canyon before reaching the adjacent plain. At the time of collecting the stream was partially dry, with some pools connected by slowly moving water and often having dense green algae. The female neotype and the biggest tadpoles were found in a deeper pool (>1 m) at the foot of a small waterfall area, which was dry (de la Riva 2002).

Relatively common at the type locality but declining in numbers. Threats include water pollution from agriculture, habitat loss from the diversion of water to use in crop irrigation, and over-collecting for medicinal use against rheumatism. The type locality (the only known locality) is not within a protected area (Stuart et al. 2008).

Telmatobius gigas is a critically endangered species of frog in the family Telmatobiidae. It is endemic to the Huayllamarca River at an altitude of about 4,000 metres (13,000 ft) in the Carangas Province in Bolivia. Its tiny range makes it highly vulnerable to pollution, and it may also be threatened by over-harvesting for medicinal use and the disease chytridiomycosis. As suggested by its scientific name, this is a very large species of frog with a snout-vent length of up to 10.9 centimetres (4.3 in) in females (males are smaller). In the genus Telmatobius, only two other threatened species, the Titicaca water frog (T. culeus) and Lake Junin frog (T. macrostomus), are larger. T. gigas is very closely related to the smaller and more widespread T. marmoratus, and they might be conspecific.