Vocal Sac-Brooding Frogs: Rhinodermatidae

The family of vocal sac-brooding frogs has only two species: Darwin's frog and Chile Darwin's frog. Both of these little frogs have flattened heads that come to a fleshy point at the tip of the snout. With their large eyes and thin, nearly beak-shaped snout, these frogs almost have a bird-like face. The pointy snout tip is especially noticeable because it comes at the end of two ridges, one found on each side of the body and extending from nearly the rump all the way to the snout. Another fainter ridge runs along the upper lip to the bottom of each large, gold-colored eye and down each front leg. The front legs are shorter than the hind legs, but all four are slender. The toes on the front feet have no webbing, but most if not all of the hind toes are at least partially webbed. Both species have a bump, or tubercle (TOO-ber-kul), on each hind foot. Their bodies may be light brown, reddish brown, brown, light green, or dark green, sometimes with brown, gray, or green markings. At least part of the underside, usually including the hind legs and lower part of the belly, is black with large white spots or blotches.

Although the two species look much alike, they are slightly different. The Chile Darwin's frog has webbing between all of the toes on its hind feet, while the Darwin's frog does not have any webbing between its outer two hind toes. In addition, the tubercles on the hind feet of the Chile Darwin's frog are larger than those on the Darwin's frog.

The two members of this family are small frogs. A male Darwin's frog grows to 0.9 to 1.1 inches (2.2 to 2.8 centimeters), and the female reaches 1 to 1.2 inches (2.5 to 3.1 centimeters). The Chile Darwin's frog is slightly larger. The male grows to 1.2 inches (3.1 centimeters), and the female reaches 1.3 inches (3.3 centimeters) in length. The males and females of both species look much alike except during the breeding season when the male's chest may be puffed up with eggs or tadpoles.