Scientists have stumbled across a new species of flying frog—on the ground.

While hiking a lowland forest in 2009, not far from Ho Chi Minh City (map), Vietnam, "we came across a huge green frog, sitting on a log," said Jodi Rowley, an amphibian biologist at the Australian Museum in Sydney and lead author of a new study on the frog.

Rowley later discovered that the 3.5-inch-long (9-centimeter-long) creature is a relatively large new type of flying frog, a group known for its ability to "parachute" from tree to tree thanks to special aerodynamic adaptations, such as webbed feet, Rowley said. (Also see "'Vampire Flying Frog' Found; Tadpoles Have Black Fangs.")

Rowley dubbed the new species Helen's flying frog, in honor of her mother, Helen Rowley, "who has steadfastly supported her only child trekking through the forests of Southeast Asia in search of frogs," according to a statement.

The newfound species—there are 80 types of flying frogs—is also "one of the most flying frogs of the flying frogs," Rowley said, "in that it's got huge hands and feet that are webbed all the way to the toepad."

"Females even have flappy skin on their forearms to glide," added Rowley, who has received funding from the National Geographic Committee on Research and Exploration. (National Geographic News is part of the National Geographic Society.) "The females are larger and heavier than males, so the little extra flaps probably don't make much of a difference," she said.

As Rowley wrote on her blog, "At first it may seem strange that such a fantastic and obvious frog could escape discovery until now—less than 100 kilometers [60 miles] from an urban centre with over nine million people."

Yet these tree dwellers can easily escape notice—they spend most of their time in the canopy, she said.

Flying Frog on the Edge

Even so, Helen's flying frog won't be able to hide from development near Ho Chi Minh City, which may encroach on its existing habitats.

So far, only five individuals have been found in two patches of lowland forest hemmed in by rice paddies in southern Vietnam, Rowley said. The animals can probably tolerate a little bit of disturbance as long as they have large trees and temporary pools, she added.

But lowland forests are among the most threatened habitats in the world, mostly because they're so accessible to people, and thus chosen for logging and development. (Get the facts on deforestation.)

"While Helen's flying frog has only just been discovered by biologists," Rowley wrote, "unfortunately this species, like many others, is under great threat from ongoing habitat loss and degradation."