World's Smallest Vertebrate: Tiny Frogs Discovered in New Guinea

LSU's Chris Austin recently discovered two new species of frogs in New Guinea, one of which is now the world's tiniest known vertebrate, averaging only 7.7 millimeters in size -- less than one-third of an inch. It ousts Paedocypris progenetica, an Indonesian fish averaging more than 8 millimeters, from the record. Austin, leading a team of scientists from the United States including LSU graduate student Eric Rittmeyer, made the discovery during a three-month long expedition to the island of New Guinea, the world's largest and tallest tropical island.

Austin, curator of herpetology at LSU's Museum of Natural Science and associate professor of biological sciences, is no stranger to discovering new species, having described numerous species previously unknown to science, including frogs, lizards and parasites.

The research, which will be published in PLoS One, on Jan. 11, includes a second species of diminutive frog newly named Paedophryne swiftorum that is only slightly larger than Paedophryne amanuensis, averaging only about 8.5 millimeters in body size.

Austin's work, supported by the National Science Foundation, highlights an interesting trend among the discovery of extremely small vertebrates.

"The size limit of vertebrates, or creatures with backbones, is of considerable interest to biologists because little is understood about the functional constraints that come with extreme body size, whether large or small," said Austin.

With more than 60,000 vertebrates currently known to man, the largest being the blue whale with an average size of more than 25 meters (75 feet) and the smallest previously being the small Indonesian fish averaging around 8 millimeters, there was originally some thought that extreme size in vertebrates might be associated with aquatic species, as perhaps the buoyancy offers support and facilitates the development of extremism. However, both new species of frogs are terrestrial, suggesting that living in water is not necessary for small body size.

"The ecosystems these extremely small frogs occupy are very similar, primarily inhabiting leaf litter on the floor of tropical rainforest environments," said Austin.