Telmatobius culeus, commonly known as the Titicaca water frog, is a very large and critically endangered species of frog in the family Telmatobiidae. It is entirely aquatic and only found in Lake Titicaca and rivers that flow into this lake in South America. While the lungs are greatly reduced, this frog has excessive amounts of skin, used to help the frog respire in the high altitude in which it lives. In reference to its excessive amounts of skin, it has also jokingly been referred to as the Titicaca scrotum water frog.