What looks like a small, bumpy stone, but chirps and hops like a cricket? The newly discovered stone leaf-litter frog (Leptolalax petrops)!
I spotted my first member of this species back in 2013, during scientific expeditions in northern Vietnam. A tiny frog, only about 3cm long, was perched on a rugged limestone outcrop covered in lush green vegetation. I’d caught its eyes shining back at me in my torch light, and climbed up to get a closer look. Staring eye to eye with the bumpy frog, I had a hunch that this little critter belonged to a species that was yet to be named.
In 2013, my colleagues and I set off with support from the National Geographic Society on two expeditions in search of rare, poorly-known and previously unknown species of amphibian in northern Vietnam. We targeted forests that had never been surveyed for amphibians and we climbed up steep forested hills and through rivers, camping in the forest at night and searching for frogs by torchlight at night (read my blog posts about the expeditions).
Each expedition lasted about two weeks and was a collaboration between biologists and students from Vietnam and Australia. Because frogs tend to be out and about most after rain, we surveyed when most sane people would avoid camping at all costs—the sweltering and mostly rainy monsoon season. Every night, we recorded all the frogs that we saw—from huge green flying frogs to the tiniest brown frogs hiding among the rocks.
After the two expeditions were completed and we’d returned home, we knew right away that we had found many rare and poorly-known frogs, but we’re only now getting answers on the last bit—figuring out which species were unknown to science.
The stone leaf-litter frog is one of the frogs that I suspected was new as soon as I laid eyes on it. Although there are much flashier frogs in the area, I’ve somehow fallen in love with the small, brownish frogs known as “leaf-litter frogs,” and so spend my time scouring the ground for them when I’m in the forest.
The species are pretty difficult to tell apart, but I’d never seen a leaf-litter frog with such bumpy, stone-like skin (females in particular are really bumpy—males are a little smoother). They looked like little gargoyles perched on the limestone rocks!
Lucky for me, during the expeditions, males of the stone leaf-litter frog, excited by the recent rains, were doing their best to attract females, allowing me to record the unique, high-pitched chirp of the males of the species (listen below). Most leaf-litter frogs have calls that resemble those of a cricket, and this species is no exception, but thankfully they sound like a slightly different kind of cricket—further evidence that they were different from other species. A look at their DNA back in the lab confirmed that these little gargoyles were indeed an unknown species. And now they’ve just been named (in this scientific publication)!
The discovery of the stone leaf-litter frog is just the tip of the iceberg when it comes to the unknown biodiversity of these forests. There’s an amazing number of plants and animals still to be discovered there—and unfortunately the forests are fast disappearing. It’s a race against time to discover the creatures that live in these mysterious forests and to ensure that they still have their forest homes in the future.