The forests of central Vietnam adjacent Cambodia are home to five new frog species that have hopefully been discovered in the nick of time.

The biodiversity of some of the most threatened ecosystems on the planet remains poorly-known. It’s a race against time to discover and document the biodiversity in these areas so that we can make informed conservation decisions. Recently, expeditions by amphibian biologists into the forests of Vietnam and Cambodia have resulted in the discovery of five new frog species. Identified largely by their chirping calls and their DNA, these tiny new frog species are further evidence that the forests in which they live are hiding a greater biodiversity than currently known. Because if this, forest loss in these areas is likely to result in an even greater biodiversity loss than we realise.

Asian Leaf-litter Frogs (genus Leptolalax) are small and brown and sound like crickets. To find one, you’ll have to trek into dense evergreen forest and quite possibly crawl on your hands and knees in the rocky headwaters of streams in Southeast Asia. Once you find one, they’re rather tricky to identify, having very few distinguishing characteristics (a small brown frog looks a lot like other small brown frogs).

Five new species of Asian Leaf-litter Frog
Top row: The Brilliant Leaf-litter Frog (Leptolalax ardens) and the Kalon Leaf-litter Frog (Leptolalax kalonensis). Bottom row: The Pale Leaf-litter Frog (Leptolalax pallidus), the Spotted Leaf-litter Frog (Leptolalax maculosus), and the Ta Dung Leaf-litter Frog (Leptolalax tadungensis). Image: Dao Tran, Jodi Rowley, Pedro Peloso
© Dao Tran, Jodi Rowley, Pedro Peloso

This is quite possibly why species discovery in Asian Leaf-litter Frogs has lagged behind many other groups of frogs, and the smallest of the frogs (the “Leptolalax applebyi group”) weren’t discovered until 2009. While their appearances can mask their true diversity, it's their faint cricket-like calls and DNA that really helps in figuring out who’s who (and who’s new).

In recent years, teams of amphibian biologists have painstakingly combed the forest floor looking for the 2-4cm frogs in the Leptolalax applebyi group. These new surveys, combined with detailed analysis of DNA, advertisement calls and morphology (body size and shape, plus colour and pattern) has resulted in us just describing an additional five new species in the group- the Brilliant Leaf-litter Frog (Leptolalax ardens), the Kalon Leaf-litter Frog (Leptolalax kalonensis), the Pale Leaf-litter Frog (Leptolalax pallidus), the Spotted Leaf-litter Frog (Leptolalax maculosus), and the Ta Dung Leaf-litter Frog (Leptolalax tadungensis).

Each new species appears to be restricted to individual drainage basins, and much of the forest in which they would have occurred in the past has already been lost. The region continues to experience high rates of deforestation, even within protected areas, and it is likely that each of these species are threatened with extinction. Undescribed species in this group likely occur in nearby unsurveyed forests and some may have already been lost (see my previous blog Gone before we know they exist).

Some of the most biodiverse places on earth are under immediate threat. In order to make informed conservation decisions aimed at stemming this loss, we need to know what species occur where and how biodiversity varies across the landcape. Our current lack of knowledge of the biodiversity of these imperiled ecosystems is hindering our conservation efforts. These five tiny new brown frogs are just the tip of the iceberg when it comes to unknown biodiversity, but demonstrate just how much remains to be discovered, and just how much we stand to lose.

Dr Jodi Rowley

More information:
Rowley, J. J. L., Tran, D. T., Le, D. T. T., Dau, V. Q., Peloso, P. L. V., Nguyen, T. Q., Hoang, H. D., Nguyen, T.T., & Ziegler, T. (2016). Five new, microendemic Asian Leaf-litter Frogs (Leptolalax) from the southern Annamite mountains, Vietnam. Zootaxa. 4085: 63–102.