Three-Toed Toadlets: Brachycephalidae

This family includes some of the smallest frogs in the world. Depending on the species, adults grow to just 0.3 to 0.8 inches (0.8 to 2 centimeters) long from the tip of the short, rounded snout to the end of the rump. Although the frogs are small, they have somewhat chunky, strong-looking bodies. Their front legs are thin and end in two, sometimes three, stubby toes. They have the bones for the other two toes under their skin, but these toes do not show. Their hind legs likewise show only three, sometimes four, very short toes. Each toe bone in the four feet is shaped like a "T" at the tip. The skeleton is also a bit odd in these frogs because it has no middle chest bone, or sternum, but does have a covering of bone across the front of the chest. Most species also have bony plates, or shields, under the skin of the back. The shield attaches to the backbone. Because of this shield, the three-toed toadlets are sometimes called saddlebacks. The southern three-toed toadlet does not have the shield.

Several of the frogs in this family, including the southern three-toed toadlet and some of the pumpkin toadlets, are bright orange. The pumpkin toadlet is sometimes yellow instead. The southern three-toed toadlet has black patches along its sides, parts of its legs, and around its eyes. Other frogs in this family are shades of brown and blend into the background a bit better.

Scientists either group all six species into one genus, called Brachycephalus or put two of the species in their own genus, named Psyllophryne. As of 2002, many scientists now use only Brachycephalus because they think all six species are very closely related. At one time, scientists thought that the three-toed toadlets should be part of the "true toad" family, named Bufonidae. When they took a closer look, however, they found that the toadlets were missing an organ that the true toads have. It is called Bidder's organ and is a small growth of female-type tissue on part of the male's reproductive system.