Newly discovered fanged frog gives birth to tadpoles

BERKELEY, Calif., Jan. 2 (UPI) -- While there is some variation on the theme, for most of the 6,000 species of frog the basic reproductive formula is the same -- a female lays eggs during mating and the male fertilizes the egg with his sperm.

"But there are lots of weird modifications to this standard mode of mating," Jim McGuire, a biologist at the University of California, Berkeley, told BBC News.

One of those modifications was adapted by Limnonectes larvaepartus, a species of frogs newly discovered by a team of scientists led by McGuire.

"This new frog is one of only 10 or 12 species that has evolved internal fertilization, and of those, it is the only one that gives birth to tadpoles, as opposed to froglets or laying fertilized eggs."

While the new frog is the only one boasting live-birthed tadpoles, it's not the only Limnonectes species. There are at least 25 types of Limnonectes frogs among the rainforests of Indonesia's Sulawesi Island, but L. larvaepartus is one of only four species to be collected and studied so far.

"This is, you know, another pretty crazy reproductive mode that's evolved within frogs," McGuire told NPR. "And so, you know, frog biologists are turned on by that sort of thing."

Researchers still aren't sure how the new species internally fertilizes the eggs. Some species of frogs use their tail as a sort of makeshift penis, pushing their sperm into their mate. But L. larvaepartus doesn't have this capability.

"They're relatively dull frogs, actually," Ben Tapley, a herpetologist at the Zoological Society of London, told BBC News. "To find out something totally surprising about a frog you would barely notice in the forest is really cool."

The strange new species of frog is profiled in the latest issue of the journal PLOS ONE.