Australia's newest frog species has a knack for mimicry, but when blending in fails, the tiny "toadlet" employs a different get-out-of-dodge tactic: distraction. When predators are closing in, this frog flashes some thigh.
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The Mahony's toadlet, Uperoleia mahonyi. Image: Sheena Martin/University of Newcastle

University of Newcastle (UN) biologist Dr Simon Clulow discovered the frog, which has been named the Mahony's toadlet (Uperoleia mahonyi), just six miles from the Newcastle airport in New South Wales. This particular find is all the more interesting because the amphibian's genus has been known to science for over a century.

"It's incredible to think this stunning little creature has been living under our noses all this time," says the UN team, noting that the toadlet's marbled underbelly sets it apart from its close kin. "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."

But let's pause here for a second – because we know you might be wondering this: What in the world is a toadlet? And why are we also calling it a frog? While baby toads are sometimes called "toadlets", in this case, the common name refers to a group of frogs with rough, gland-covered backs. The glandular bumps give the amphibians a similar look to European and American toads.

Small enough to sit comfortably on a fingertip, the Mahony's toadlet is particularly good at hiding. In fact, it was only by trained ear that Clulow and his colleagues managed to find one in the first place. "[We were] following the male advertisement or 'mating' call," he says.

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Image: Sheena Martin/University of Newcastle
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Image: Sheena Martin/University of Newcastle
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Image: Sheena Martin/University of Newcastle

The animal's colouration helps conceal it against sand, leaf litter and native grasses, but upon closer inspection, the team discovered that this brindled pattern is accented by four bright swatches of colour on the upper legs. This, Clulow explains, is the mark of a "flasher" frog.

"If a predator comes across the frog, the frog will flash a brilliant burst of orange as it attempts to leap to safety," he says. "This is thought to momentarily startle the predator, helping the frog to survive another day!"

Finding new vertebrate species amidst the urban sprawl is relatively rare, but it does happen – and as we continue to move in on wild habitats, we'll likely see it happen with greater frequency. The Mahony's toadlet can be found in just a few white-sand coves, which of course, also attract human holidaymakers. 

"Coastal areas such as those inhabited by this new species are highly attractive residential development locations," adds Clulow. "Sadly, this threat, combined with the limited distribution of the frog, could result in it being immediately listed as a threatened species." 

And sadly, all around the world, ambibians are facing simlar threats: nearly 40 percent of species are currently in decline or already extinct. Back in September, we said goodbye to the last known Rabbs' fringe-limbed tree frog, a male known as "Toughie", whose story was featured in the film Racing Extinction. Toughie was removed from the wild in 2005, a time with the deadly chytrid fungus threatened to wipe out Panama's amphibians.

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Image: University of Newcastle

Eastern Australia has more recently been identified as a global hotspot of frog decline. Chytrid has also reared its ugly head here, and combined with development and a growing sand mining industry, the region's amphibians are at particular risk.

Under law, ecological surveys must be carried out before areas of developmental interest can be turned over in New South Wales, but this latest addition to the amphibian family shows us just how easily a species can be overlooked. The new frog now shares what's left of its habitat with humans.

"The locality where the frog was initially discovered is a former sand mine rehabilitation area where an environmental assessment would have been carried out," writes the team. "It is unlikely that the species has never been detected, but failure to identify it as an undescribed species highlights the problem of [non-specialists] conducting surveys."