Posts on Amphibians

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.

References:

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

Borneo Rainbow Toad Rediscovered

10 July 2012

This time last year Borneo’s amazing biodiversity again made widespread news with the rediscovery of the long lost Borneo Rainbow Toad. In July 2011 researchers from the University of Malaysia Sarawak (UNIMAS) led by herpetologist Dr. Indraneil Das made an extraordinary find in the mountains of western Sarawak. Three small amphibians were observed in the branches of a tree, and upon close inspection these were revealed to be none other than Ansonia latidisca, a species which had not been seen since 1924.

Measuring up to 5 cm in length, this toad is one of the largest and certainly most colorful in the genus Ansonia. Although the dorsum is richly patterned with green, yellow, purple, and brown with red-tupped warts, the general appearance is somewhat “mossy” and this may serve to camouflage the animal from potential predators.

The rediscovery of this species brings some much-needed hope in the face of ever-increasing worldwide amphibian extinctions, particularly as Conservation International had previously listed the Borneo Rainbow Toad as one of the “world’s top 10 most wanted frogs” in their Global Search for Lost Frogs in 2010. Nevertheless, amphibians remain the most threatened group of vertebrates on the planet, with severe threats coming from habitat loss, climate change, and the dreaded chytrid fungus (Batrachochytrium dendrobatidis).

Photographs are still scarce of this elusive species, and little is known of its life cycle, behavior, or remaining popultion.

Ansonia latidisca


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