But one thing sets the Vietnamese croaker apart from any known species on Earth: As a baby, it boasts a pair of black fangs, earning it the world's best amphibian nickname: vampire flying frog.

"Fangs have never been seen before in a tadpole," said Bryan Stuart, a Raleigh scientist who is part of a team that discovered it. "This is such an exciting time to be an amphibian biologist."

Stuart is the curator of amphibians and reptiles at the N.C. Museum of Natural Sciences, which will hold its annual Reptile and Amphibian Day on March 12.

Speaking from his office where he keeps a Gila monster rescued from an Arizona swimming pool, Stuart focuses much of his work in Southeast Asia, where he also trains biologists to identify and inventory new species.

Since 2008, he and a pair of scientists from Australia and Vietnam have been hunting the Vietnamese Langbian Plateau for undiscovered amphibians.

Among the four new species, they located a frog that stretches only about 2 inches long as an adult, and can steer its body while gliding from branch to branch in search of bug prey.

It lays its eggs in rain-filled holes, normally as high as the uppermost branches. But the scientists were lucky enough to spot some at eye-level, where the fanged young frogs were discovered.

In the December edition of the journal Zootaxa, Australian scientist Jodi Rowley described, "most notably, a pair of keratinized hooks on the edge of the lower labium that face away from the mouth."

But more than just a fancy new frog, the find in Vietnam signals wide frontiers full of undiscovered species, amphibians in particular.

By 2006, more than 6,600 species of amphibians had been identified, most of them toads and frogs. That's about 50 percent more than were known in 1985.

Part of the reason for the amphibian explosion is that regions once unavailable for sampling are now open to researchers, Stuart says. Another is the technology used to identify new species, both through DNA and through acoustic tools that detect their calls. Frogs recognize each other through noises, while humans have always picked them out by sight.

"When you look at these amphibians in your hand, they look the same," Stuart said. "We've missed them."

The habitat in Vietnam where the vampire frogs have been found is increasingly threatened by coffee plantations as demand grows for Vietnamese beans.

But the frogs collected by Stuart and his colleagues - eight in all - were found in a protected national park area. It isn't known how abundant they are in this location, or even what their tadpole fangs are used for. By the time the rhacophorus vampyrus reaches adulthood, the fangs fall out.

This, however is certain: "They don't suck blood," Stuart said.