New Species of Gliding Frog from Borneo

18 September 2013

Few animals seem to encapsulate the magical qualities of the Bornean jungle more than gliding frogs. Armed with huge webbed feet and flaps of skin along their limbs, these colorful amphibians sport the uncanny ability to paraglide down from the tree tops and even change directions in mid-flight. Once, during a visit to the canopy walkway in Danum Valley Conservation Area in Sabah, I witnessed firsthand just how effective the gliding ability of these frogs can be. Upon arriving at a tree platform in the middle of the walkway, perhaps 50 meters above the forest floor, I noticed a small orange frog (Rhacophorus pardalis) perched on one of the wooden planks near the edge. As I approached for a closer look it abruptly leapt off the platform and I watched as it soared down through the air, carved a wide arc around a lower tree and disappeared into the forest below.

Several gliding frog species occur in Borneo, all in the genus Rhacophorus and all equally charming with their gaudy colors and oversized (seemingly ungainly) floppy feet. The most well-known is undoubtedly the large and spectacular Wallace’s Flying Frog (Rhacophorus nigropalmatus), made famous by Alfred Russel Wallace’s description and illustration in The Malay Archipelago. Smaller, but no less attractive is the Harlequin Flying Frog (Rhacophorus pardalis) which is perhaps the most common of the species, being found all across the island around muddy pools of water in the forest.

Last month a scientific paper published in Current Herpetology brought to light an entirely new species, the Bornean Gliding Frog (Rhacophorus borneensis). Perhaps the most colorful of all the Rhacophorids, R. borneensis is a pale lime-green with an orange underside and interspersed with patches of black and brilliant sky-blue. This frog had been known previously from a few scattered collections and photos from Sarawak and Sabah, but was thought to belong to the Javan Flying Frog (Rhacophours reinwardti). The new research compared both color patterns, size, and DNA, and showed that the Bornean specimens are indeed distinct from R. reinwardti, which is now believed to occur only in Java.

Rhacophorus borneensis

Like other gliders, R. borneensis is a true tree frog, and it is believed to live almost its entire adult life in the forest canopy, descending to pools of water only to breed and lay eggs. Simply judging by how rare encounters with this species are, its visits to ground level are probably even more infrequent than R. nigropalmatus or R. pardalis. The presence of R. borneensis in the forest is often only detected by the distinctive call of the male, sounding somewhat like a woodpecker drumming on a hollow tree.

So far the life-history of the Bornean Gliding Frog remains almost completely unstudied, but further research is certainly warranted for this newest member of Borneo’s magnificent gliders.


M. Matsui, T. Shimada, A. Sudin. A New Gliding frog of the Genus Rhacophorus from Borneo. Current Herpetology, August 2013; 32(2): 112-124.

The Nature of Sulawesi: Guided Tour 3-20 August 2013

17 September 2013

During our epic 3-week traverse of Sulawesi and Halmahera the group bravely faced bloodsucking leeches, overgrown trails, and several flooded rivers, but were well rewarded with some incredible sightings of rare flora & fauna. Some highlights of the trip included: close encounters with tarsiers and macaques in Tangkoko, a very rare sighting of a Lowland Anoa, and reaching the summit ridge of Gunung Lumut after several days of hiking to find the remarkable pitcher plant Nepenthes hamata.

A selection of images from the trip:

Macaca nigra nigraNepenthes hamataEurystomus azureusBabyrousa celebensis
Agalmyla sp.Gehyra marginataLitoria sp.Gunung Kiematabu
Nepenthes eymaeLitoria infrafrenata infrafrenataTodiramphus diopsXylotrupes ulysses clinias
Nepenthes glabrataBabalus depressicornisThe Nature of Sulawesi guided tour 2013Turacoena manadensis

Additional photos from the trip can be found at Rainforest Expeditions with Chien Lee on Facebook.

A new tour to Sulawesi has been scheduled for February-March 2014. Please inquire for further details.

New Species of Bornean Slow Loris

15 December 2012

The sight of a Slow Loris (Nycticebus menagensis) staring down at you from the rainforest canopy, its eyes brightly illuminated by your headlamp, is always an exciting find. It was only three weeks ago, whilst I was on a nocturnal foray with a group of photographers in the jungles bordering Sarawak and Kalimantan, that I had my most recent encounter with a loris. Unfortunately, these nocturnal primates are nowhere abundant and sightings of them uncommon at best, due in part to patchy distributions and also sadly, capture for the pet trade.

A new paper in American Journal of Primatology presents a dramatic new view of the loris diversity in Borneo. Previously, three subspecies of loris were known from the island: N. m. bancanus, N. m. borneanus, and N. m. menagensis, which differed from each other in fur coloration and body size. However, taking into account other recent findings in loris diversity, the reseachers of the present paper undertook a thorough investigation on the variation of Bornean lorises, which had never been studied in great detail.

After critically examining a number of museum specimens and carefuly comparing their morphology and corresponding geographic locations, they concluded that there were not three, but four distinct loris types on Borneo, and went further to elevate each of these to its own species status. Thus the presently recognized species now include: N. bancanus, N. borneanus, N. menagensis, and the new N. kayan.

Several months ago I received an email from Dr. Anna Nekaris, who heads The Little Fireface Project, a non-profit organization dedicated to loris research and conservation. She pointed out that one of the animals which I had photographed in Sarawak several years ago represented the newly described Nycticebus kayan (pictured below). Specifically, the Kayan Loris can be distinguished from other Bornean lorises by a combination of features including its highly contrasting and distinctive face mask.

Nycticebus kayan

Like all lorises, the Kayan Loris is primarily nocturnal and feeds on a variety of insects and soft fruits. Lorises are also unique among primates in that they possess a venomous bite which is used in self-defense. The bite can cause fever, pain, and swelling, and in people who happen to be allergic the results may even be fatal. One Sarawakian who I met in Mulu National Park, had to be hospitalized for several days after being bitten when handling a wild loris.

Although more research, including genetic studies, remains to be done on Bornean lorises, the new discovery helps not only to shed light on the variations of these nocturnal primates, but also is a testament to the amazing diversity which is continuing to be revealed within Southeast Asian rainforests.


R. Munds, S. Ford, K.A.I. Nekaris. Taxonomy of the Bornean Slow Loris, with New Species Nycticbus kayan (Priamtes Lorisdae). American Journal of Primatology, December 2012; DOI: 10.

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