Telmatobius culeus, commonly known as the Titicaca water frog or Lake Titicaca frog, is a medium-large to very large and endangered species of frog in the family Telmatobiidae. It is entirely aquatic and found only 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.