Leaping their way through Borneo’s dense rainforest vegetation, frogs are the ‘forest’s barometers’. Abundant and easy to observe, their sensitivity to ecological and climate change makes them excellent indicators for assessing forest condition.1
Borneo amphibians
Meet Borneo’s organic barometers
Caption: In 2008 scientists found out that the up to 7cm long Bornean flat-headed frog (Barbourula kalimantanensis) is the world?s first lungless frog. Instead of lungs, this unique species breathes entirely through its skin. Other organs can be found in the place lungs would normally be, which makes the overall appearance of the frog flatter. As well as a larger surface area with which to absorb more oxygen, scientists believe this flatter and more aerodynamic shape allow the frogs to maneouvre more capably in the fast flowing streams the species inhabits in the Kalimantan rainforest, in the Heart of Borneo.
The species was first discovered in 1978 and is currently listed as Endangered on the IUCN Red List of Threatened Species. It is known only from two locations in the middle of the Kapuas River Basin, where the species is threatened by pollution from mining activities.
Irregulary distributed on Borneo
While amphibians are ubiquitous in Borneo, their distribution on the island is far from uniform. For instance, some 2/3 of all known Borneo amphibian species are found in Gunung Mulu National Park (Sarawak, Malaysia), including the visually striking Wallace’s flying frog (Rhacophorus nigropalmatus).Some species show very restricted ranges, such as Philautus saueri, which is known from no more than 5 locations in Sabah, Malaysia.2 This species has the unique habit of placing its eggs and larvae in the receptacles of pitcher plants (Nephentes species).3
Creative solutions for survival
Other frog species lay their eggs along rivers, or store them in tree cavities where rainwater has accumulated, about 1 m - 4 m from the ground. Such is a technique developed by the lowland tree frog (Rhacophorus harrissoni), found below 250 m in altitude.4Amphibians in all sizes
Equally impressive is the sheer variety of forms and adaptations seen in this wildlife group. For example, amphibians range in size from the tiny sharp-snouted bush frog (Philautus ingeri) - about 3.6 cm in length for males5 - to the giant river toad (Bufo juxtasper) - up to 30 cm in size. 6Forest camouflage
Much less conspicuous than its giant relative, the Malayan horned frog or horned toad (Megophrys nasuta) blends in a remarkably convincing way with the surrounding vegetation.By changing its colour, it mimics the colour of leaves on the forest floor. This frog’s physical characteristics help it to hide, with sharply pointed protuberances above each eye that reinforce its camouflage.
Recently discovered
- Kalophrynus eok, a new frog species in the Kelabit Highlands of Sarawak (North Central Borneo). These ground dwelling animals are also called ‘Sticky frogs’ as they secrete a sticky, poisonous mucus when attacked.
- Philautus erythrophthalmus, the dwarf red-eyed tree frog from Sabah, at 1,550 m above sea level in a montane oak forest. Species of this genus are unusual in that tadpoles do not develop in the water.
- Ansonia anotis, a species of the Ansonia toad group in the highlands of Sabah. In contrast to other Ansonia toad, this new species does not have a hearing organ and the tadpole stage has a distinct abdominal sucker, which it may use for climbing.
- The discovery of the Bornean flat-headed frog in the middle of the Kapuas River basin some years ago was quite spectacular, since this species represented a family of frogs previously unknown from Borneo. But this species may be lost before it is well observed. The area where it occurs is now highly disturbed due to illegal gold mining.
More than 3 species discovered every month during the past 15 years
Between 1995 and 2010 more than 600 species have been discovered - that is 3 species each and every month.
Download
Wallace’s flying frog
This large species has black, green and yellow patterns, and characteristic webbed feet that allow it to glide from one tree to another. The only time it is found on the ground is during mating, when it constructs a bubble nest.
A colour-changing flying frog
This unique frog was found 1,650m above sea level in Gunung Mulu National Park, Sarawak, in the Heart of Borneo. The species is known only from the Tapin Valley near a small stream in the area, making it highly endemic.
Tiny, with males growing to just 3.5cm, the Mulu Flying Frog as it is commonly known has a small pointed snout and is unusual in that the species has bright green skin at night but changes colour to display a brown hue during the day.
Tiny, with males growing to just 3.5cm, the Mulu Flying Frog as it is commonly known has a small pointed snout and is unusual in that the species has bright green skin at night but changes colour to display a brown hue during the day.
read more
references
1 Iskandar D. 2004. The amphibians and reptiles of Malinau Region, Balungan Research Forest, East Kalimantan. CIFOR: Bogor.
2 IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. Accessed 10 April 2006.
3 UNEP/WCMC. Gunung Mulu National Park. Accessed 10 April 2006.
4 IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. Accessed on 10 April 2006.
5 Asean Regional Centre for Biodiversity Conservation. BISS – Philautus ingeri. Accessed online on April 9 2006.
6 Iskandar D. 2004. The amphibians and reptiles of Malinau Region, Balungan Research Forest, East Kalimantan. CIFOR: Bogor.
2 IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. Accessed 10 April 2006.
3 UNEP/WCMC. Gunung Mulu National Park. Accessed 10 April 2006.
4 IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. Accessed on 10 April 2006.
5 Asean Regional Centre for Biodiversity Conservation. BISS – Philautus ingeri. Accessed online on April 9 2006.
6 Iskandar D. 2004. The amphibians and reptiles of Malinau Region, Balungan Research Forest, East Kalimantan. CIFOR: Bogor.
