Chuck Bednar for redOrbit.com – Your Universe Online
A new species of fanged frog found on the Indonesian island of Sulawesi gave birth to live tadpoles–something extremely rare in frog species.
Limnonectes larvaepartus was discovered this summer by University of California, Berkeley herpetologist Jim McGuire when he picked up what he thought was a male frog, only to find dozens of newborn tadpoles in his hands, as well.
For McGuire, this was direct evidence that female L. larvaepartus gives birth to live tadpoles instead of laying eggs, making it another in a dozen frog species in the world that give birth through internal fertilization.
“Almost all frogs in the world – more than 6,000 species – have external fertilization, where the male grips the female in amplexus and releases sperm as the eggs are released by the female,” said McGuire. “But there are lots of weird modifications to this standard mode of mating. This new frog is one of only 10 or 12 species that has evolved internal fertilization, and of those, it is the only one that gives birth to tadpoles as opposed to froglets or laying fertilized eggs.”
According to McGuire, frogs have evolved a tremendous variety of reproductive method over the years. In most cases, males fertilize eggs after the female lays them, but California’s tailed frogs and some other species have developed ways to fertilize eggs inside the female’s body.
There are also several other reproductive variations in frogs. Some frogs, for instance, carry eggs in pouches on their backs, while others brood tadpoles in their vocal sac or mouth and still others transport their young in pits on their back, the researchers said. The females of some now extinct species even swallowed their eggs and later gave birth to froglets through their mouths.
“The new species,” the university explains, “seems to prefer to give birth to tadpoles in small pools or seeps located away from streams, possibly to avoid the heftier fanged frogs hanging out around the stream. There is some evidence the males may also guard the tadpoles.”
McGuire and his colleagues note that fanged frogs were named because of the two fang-like projections that extend from their lower draw and are used in fighting. They believe that there may be as many as 25 species of these frogs living on Sulawesi, though the five-to-six gram L. larvaepartus is just the fourth to be formally identified.
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