Meet the Thorny Tree Frog: a striking new frog species from Vietnam

Males of this newly discovered pink and yellow tree frog are covered in prickly, white-tipped spines.

A new species of frog has just been discovered from the forested mountains of central Vietnam. The species, previously unknown to science, is about 4 cm (2.5 inches) long, and coloured pink and yellow. Most unusually, males of the species sport sharp spines all over their head and back. It’s because of these spines, or ‘thorns’, that the species has been named the Thorny Tree Frog (Gracixalus lumarius).

Discovering the Thorny Tree Frog wasn’t easy, as it is only known from above 1,800 m (~6,000 ft) on the highest mountains in central Vietnam, Mount Ngoc Linh and surrounding peaks. In 2009 and 2010, amphibian biologists from Vietnam and Australia conducted scientific expeditions in these mountains, climbing up steep slopes and rocky streams at night in search of amphibians.

A number of new species have been described from these mountains in the last decade, and almost all of them are found nowhere else on earth. Adapted for life on the cold, wet mountains peaks, many species have evolved in isolation. The Misty Moss Frog (Theloderma nebulosum) and Orange-bellied Leaf-litter Toad (Leptolalax croceus) are other amphibian examples known only from these mountains.

So why the “thorns”? Well, it seems that only male Thorny Tree Frogs sport spines, and that these become bigger and more impressive in the breeding season. So perhaps the spines help females of the species figure out whether or not a male is ready to breed.

Living on the steep sides of a cold, wet mountain, the Thorny Tree Frog has another uncommon adaptation. Instead of laying eggs in a stream or pool, it lays its eggs above small, water-filled hollows in trees. Tadpoles of the species likely develop into frogs in these hollows, safe from most of the predators that lurk in larger water-bodies.

The future of the Thorny Tree Frog, like many Southeast Asian amphibians, is uncertain. With the highest deforestation rate on the planet, the poorly-known amphibians of Southeast Asia are facing some serious and increasing threats. Because the Thorny Tree Frog is likely to be restricted to a small area on the upper slopes of a few mountains, it is likely to be particularly vulnerable to threats such as habitat loss and fragmentation, collection for the pet trade, and climate change. Now that we know the species exists, we hope to ensure its continued survival.

Dr Jodi Rowley
Curator, Amphibian & Reptile Conservation Biology, Australian Museum Research Institute & UNSW Sydney

More information:
Rowley, J. J. ., Le, D. T.T., Dau, V. Q., Hoang, H. D., & Cao, T. T. (2014) A striking new species of phytotelm-breeding tree frog (Anura: Rhacophoridae) from central Vietnam. Zootaxa. 3785: 25–37.