A tiny little frog that looks almost the same as another species has just been revealed from the imperiled forests of Southeast Asia

Sometimes looks can be deceiving. Although nearly identical in appearance to another species, a new species of Asian Leaf-litter Frog (Leptolalax isos) has just been identified from the hilly forests of Cambodia and Vietnam. First seen by biologists in 2006, revealing its identity took detailed comparisons of body size, advertisement calls and DNA. The discovery of Leptolalax isos adds to our knowledge of the rich and threatened biodiversity of Southeast Asia.

Leptolalax isos
Leptolalax isos Image: Jodi Rowley
© Australian Museum

In 2006, my colleagues and I came across a small brown frog species and an even smaller brown frog species in Virachey National Park in northeastern Cambodia. At the time, we weren’t too sure of the identity of either of these frog species. In 2010, after examining museum specimens, DNA and recorded advertisement calls, we described the smaller of the two as the Musical Leaf-litter Toad (Leptolalax melicus), after its rather melodious call. The larger of the two small brown frogs took additional detective work, and finding more individuals of the species in neighboring Vietnam to convince us that it was a new species, and not the similar-looking Firth’s Leaf-litter Frog (Leptolalax firthi). We named it Leptolalax isos because of this similarity ("isos" means equal or like in Greek).

The new species of frog is less than 3 cm long, lives in forest from ~650–1100 m elevation and breeds in small rocky streams northeastern Cambodia and adjacent Vietnam. Unfortunately the forests in which it depends are being lost due to logging, agricultural expansion and hydroelectric projects.

The discovery of Leptolalax isos adds to our ever-increasing knowledge of the biodiversity of Southeast Asia. Given the high rate of forest-loss throughout the region, even within officially protected areas, it’s vital to have a more accurate understanding of the patterns of biodiversity throughout the region, so that we can ensure that our limited conservation resources go to the places and the species that need it most. This little frog is just the latest piece in the biodiversity puzzle of the region, but its discovery will hopefully help inform biodiversity management in the area.

Dr Jodi Rowley, AMRI

More information:
Rowley, J.J.L., Stuart, B.L., Neang, T.,Hoang, H.D., Dau, V.Q., Nguyen, T.T. & Emmett, D.A. (2015). A new species of Leptolalax (Anura: Megophryidae) from Vietnam and Cambodia. Zootaxa 4039: 401–407.

This research was supported by grants from the ADM Capital Foundation, The John D. and Catherine T. MacArthur Foundation, the Annie Alexander Endowment, Museum of Vertebrate Zoology, University of California, Berkeley, Conservation International and a STMVQG 06G14-16 project.