Researchers say they've found a new kind of frog that might be the smallest such amphibian living outside the Americas.
The pea-sized frog, dubbed Microhyla nepenthicola, measures between 10.6 and 12.8 millimeters in length, making it small enough to live inside puddles that accumulate in pitcher plants in the forests of the Southeast Asian island.
Despite the frog's small size, Robin Moore, amphibian conservation officer with Conservation International, says the tiny species represents a big scientific discovery.
"Such small species are very interesting because they've really reached the boundaries of what is possible in the animal world," Moore said. "These are some of the smallest tetrapods -- or four-legged organisms -- in the world."
"Their size is very interesting from an evolutionary point of view," Moore added. "What it allows these frogs to do is exploit new habitats."
In this case, the miniature frogs use their small size to live inside a pitcher plant -- a kind of flora that feeds off of decomposing organic matter that it collects inside a pitcher-shaped chalice.
The frogs lay their eggs on the plant, and the tadpoles mature in puddles inside the plant's pitcher.
While the plant provides a safe habitat for the frogs, it's unclear what, if anything, the tiny amphibians give back to their botanical abode.
"I'm not sure if [the pitcher plant] is getting much out of it, but maybe the tadpoles or the frogs are excreting things into the water that the plant is using as a food source," Moore speculated.
Just a handful of species of frogs are thought to be smaller, such as Brazil's gold frog and Cuba's Eleutherodactylus iberia. And this newfound frog is the smallest such animal in the Old World, the researchers wrote in an article in Zootaxa (PDF).
The diminutive frogs are so tiny they were once overlooked by scientists.
Lead researcher Indraneil Das told The Christian Science Monitor that scientists had actually discovered the frog more than 100 years ago but "presumably thought they were juveniles of other species."
Thankfully, for Das, these puny frogs happen to have big voices.
Das and his research partner, Alexander Haas, were in Kubah National Park when they heard the tiny frogs making calls (listen here) -- a behavior only exhibited by adult frogs.
Das eventually trapped one specimen in a clean white diaper he had brought along for his baby son, according to the New York Post.
"It's the call that actually gave it away," Moore said.