Telmatobius culeus

Telmatobius culeus, commonly known as the Titicaca water frog, is a medium-large to very large and endangered species of frog in the family Telmatobiidae. It is entirely aquatic and only found in the Lake Titicaca basin, including rivers that flow into it and smaller connected lakes like Arapa, Lagunillas and Saracocha, in the Andean highlands of Bolivia and Peru. In reference to its excessive amounts of skin, it has jokingly been referred to as the Titicaca scrotum (water) frog. It is closely related to the more widespread and semiaquatic marbled water frog (T. marmoratus), which also occurs in shallow, coastal parts of Lake Titicaca, but lacks the excessive skin and it is generally smaller (although overlapping in size with some forms of the Titicaca water frog). In the late 1960s, an expedition led by Jacques Cousteau reported Titicaca water frogs up to in outstretched length and in weight, making these some of the largest exclusively aquatic frogs in the world (the exclusively aquatic Lake Junin frog can grow larger, as can the helmeted water toad and African goliath frog that sometimes can be seen on land). The snout–to–vent length of the Titicaca water frog is up to , and the hindlegs about twice as long. Most individuals do not reach such sizes, but are still big frogs. Titicaca water frogs of the largest and typical form, upon which the species was first described, usually have a snout–to–vent length of and weigh less than . This typical form tends to inhabit relatively deep water in eastern Lake Titicaca, but a minority of the individuals in the Coata River (which flows into far western Lake Titicaca) are similar. Several other forms are found at shallower depths in Lake Titicaca, in smaller lakes that are part of the same basin, and in rivers and streams that flow into Titicaca. These tend to be smaller in size with a snout–to–vent length of and historically they were recognized as separate species (T. albiventris and T.