Amero-Australian Treefrogs: Hylidae

Physical characteristics: Also known as the Ecuadorian marsupial frog, the Riobamba marsupial frog gets its name from the pouch, or marsupium (mar-SOUP-ee-uhm), on the rear of the female's back. The male has no pouch. The Riobamba marsupial frog is a plump green to brown frog sometimes with darker colored oblong blotches of color on its back. The blotches are outlined in dark brown. Its back is smooth or has a cracked appearance. Its underside is grainy-looking, has a cream color, and is sometimes spotted with gray or brown. The frog has a small head with large, brown eyes and a wide mouth on its The female Riobamba marsupial frog carries her eggs in pouch on her back (Photograph from the Kansas University Natural History Museum. Reproduced by permission.) rounded snout. All four of its short legs have toes with slightly rounded pads on the tips. Males may be a bit shorter than females. Males usually grow to 1.4 to 2.3 inches (3.4 to 5.7 centimeters) from snout to rump, while females reach 1.4 to 2.7 inches (3.4 to 6.6 centimeters) in length. Until 1972, this frog's scientific name was Gastrotheca marsupiata, but that name is now used by a different species found only in Peru and Bolivia.

Geographic range: It lives in northwestern South America among the Andes mountains in parts of Ecuador.

Habitat: It lives along the ground, making its home in mountain fields, farmlands, and even city gardens.

Diet: It eats beetles, as well as other arthropods.

Behavior and reproduction: The Riobamba marsupial frog hides during the day in small openings in rock piles and stone walls and among plant leaves. At night, it becomes active and looks for food on the ground. The frog is most known for the unusual way it has its young. Mating begins when the male calls with a "wraaack-ack-ack" sound and attracts a female. In most frogs, the male sheds fluid, which contains microscopic cells called sperm, over the female's eggs as she lays them. Only after the sperm mixes with the eggs can they start developing into baby frogs. In the Riobamba marsupial frog, the male sheds the sperm-filled fluid, but spreads it on her back behind her pouch. As she lays her eggs, he pushes them through the fluid and into her pouch. A single female may lay sixty-four to 166 eggs at a time. The eggs hatch inside her pouch seventy to 108 days later. The female moves to shallow water, pulls open the pouch, and the tadpoles swim out. The female uses her hind feet to scoop out any stragglers. The tadpoles change into froglets in four to 12 months.

Riobamba marsupial frogs and people: Scientists are interested in the frog because of the unusual way it reproduces.

Conservation status: The IUCN lists this species as Endangered, which means that it faces a very high risk of extinction in the wild. It was once a common species, but now is rare. Scientists are not sure why its numbers have dropped, but they think that the change in its habitat from forests and meadows to farm fields is likely part of the reason. ∎