(Reuters) - A new species of frog, whose groin flashes orange to scare away predators, has been discovered in Australia.

When biologist Simon Clulow spotted the frog's unusual marble pattern on its belly, he knew it could be a previously unknown species, a find made all the more unusual as it was not in a remote habitat but on land close to an airport.

"Nowadays many new discoveries are based primarily on genetics, that is, the frogs look similar to other known species but when we analyze them in the lab we find they differ genetically," said Clulow, of the University of Newcastle, Australia.

"It's almost unheard-of to pick up a vertebrate in the field and know instantly, based on appearance alone, that it is a new species."

The species, found at Oyster Cove near Newcastle Airport in New South Wales, has been dubbed uperoleia mahonyi, or "Mahony's Toadlet", in honor of Clulow's mentor, frog expert and conservationist Professor Michael Mahony.

Although a frog rather than a toad, the word "toadlet" was added because the glands on its back look like those found on some toads in Europe and the Americas.

"They are highly secretive. Individuals remain well camouflaged and hidden under grass, leaves and sand," Clulow said, adding that the best way to find them is by following their mating call, an audible "squelch" of less than a second.

When confronted by predators, the frog extends its legs and flashes its orange groin, which Clulow believes briefly startles predators, allowing it to escape. His findings, with co-authors, is published in peer-reviewed journal Zootaxa.

(Reporting by Reuters Television; Editing by Robin Pomeroy)