Ruthven's Frog: Allophrynidae

Ruthven's frog is a metallic brown color, sometimes yellow- or gray-brown, with darker marks and lighter yellow-brown or gold stripes down each side of the back. The back of its long body is scattered with tiny spikes, or spicules (SPIK-yuhlz), that are partly buried in the skin. The spicules in males are larger than those in females. Because of the spicules, which look somewhat like warts, people often describe this frog as toadlike. It has large eyes that bulge from each side of its head. The head becomes flatter toward the front. Its front and back legs are thin, and the toes end in rounded pads. The front legs often have noticeable light-colored spots that extend onto the chest and throat. Light-colored spots also cover the lower part of its head around the mouth. Often, the sides of the body and parts of the legs have a pink, see-through appearance.

Males have a dark, unspotted area on the throat that remains hidden except when they call. During calling, this area, called a vocal sac, blows up to a large size—at least the size of the head and sometimes much larger. The females grow slightly larger than the males. Females typically reach 0.85 to 1.20 inches (2.2 to 3.1 centimeters) long from snout to rump, and males usually grow to 0.8 to 1 inch (2.1 to 2.5 centimeters) in length.

Discovered in 1926, the single species of Ruthven's frog has at one time or another been listed in five different frog families, including the true toads, the glass frogs, the leptodactylid frogs, the tree frogs, and its own separate family, as it is listed here. Scientists have found no fossils to study. The confusion in the listing of this frog's family comes from the fact that the frog has some features of all of the different families. For example, its toe bones are T-shaped at the tips, which scientists once thought was like the toes of the glass frogs or possibly the tree frogs. Studies since then showed that the toe bones of Ruthven's frogs are actually slightly different than those of either the glass or the tree frogs.

During the mating season, male Ruthven's frogs call from plants and trees above ponds, and females lay their eggs in the water, which is the same situation as seen in the tree frogs. Like true toads, Ruthven's frogs have no teeth. In fact, the scientific name of Ruthven's frogs, Allophryne, means "other toad," because it was thought to be a new kind of true toad.

Ruthven's frog's full scientific name is Allophryne ruthveni. Like many other species of plants and animals, the second part of its name refers to a person or to the place where it was collected. In this case, the name refers to Alexander Ruthven, a noted herpetologist (her-peh-TOL-eh-jist) who was very active in the first half of the twentieth century. A herpetologist is a person who studies amphibians and reptiles. Ruthven, who was curator of the Division of Reptiles and Amphibians at the University of Michigan Museum of Zoology, led eighteen of the museum's expeditions to places throughout the United States, Mexico, Central America, and South America.

In 2002, a group of scientists compared the DNA of Ruthven's frogs to the DNA of other frogs. DNA is a string of chemicals that provides the instructions for making a living thing. By comparing the DNA of different organisms, scientists can tell how similar they are. The comparison showed that Ruthven's frogs may be most closely related to the glass frogs and perhaps should be considered members of that family. Until more studies are done, however, many scientists list Ruthven's frogs as the lone members of its own family, called Allophrynidae, while some others still place it in the family Hylidae. In 2003, scientists In 2002, a group of scientists compared the DNA of Ruthven's frogs to the DNA of other frogs. The comparison showed that Ruthven's frogs may be most closely related to the glass frogs and perhaps should be considered members of that family. (Illustration by Dan Erickson. Reproduced by permission.) discovered what they believe may be a second species of Ruthven's frog. It is black with bright white and yellow spots and has two bulging eyes, one on each side of its head.