The Bornean flat-headed frog has no lungs and breathes entirely through its skin. It is one of the discoveries of a project to conserve one of the oldest rainforests in the world. (David Bickford/World Wildlife Fund/Associated Press)

A lungless frog, a frog that flies and a slug that shoots love darts are among 123 new species found in Borneo since 2007 in a project to conserve one of the oldest rainforests in the world.

A report by the World Wildlife Fund on the discoveries also calls for protecting the threatened species and equatorial rainforest on Borneo, the South China Sea island that is the world's third-largest and is shared by Malaysia, Indonesia and Brunei.

"The challenge is to ensure that these precious landscapes are still intact for future generations," said the report released Thursday.

The long-tailed slug, Ibycus rachelae, uses 'love darts' made of calcium carbonate to pierce and inject a hormone into a mate to increase the chances of reproduction. (Peter Koomen/World Wildlife Fund)

The search for the new species was part of the Heart of Borneo project that started in February 2007 and is backed by the WWF and the three countries that share the island.

The aim is to conserve 220,000 square kilometres of rainforest that was described by Charles Darwin as "one great luxuriant hothouse made by nature for herself."

Explorers have been visiting Borneo for centuries, but vast tracts of its interior are yet to be biologically explored, said Adam Tomasek, leader of WWF's Heart of Borneo project.

"If this stretch of irreplaceable rainforest can be conserved for our children, the promise of more discoveries must be a tantalizing one for the next generation of researchers to contemplate," he said.

The zebra-striped Eirmotus insignis is another recent discovery in Borneo. (CK Yeo/World Wildlife Fund, /Associated Press)

The scientists' discoveries include the world's longest known stick insect at 56.7 centimetres, a flame-coloured snake and a frog that flies and changes its skin and eye colour. In total, 67 plants, 29 invertebrates, 17 fish, five frogs, three snakes and two lizards and a new species of bird were discovered, said the report.

Borneo has long been known as a hub for monster insects, including giant cockroaches about 10 centimetres long.

Notable among the species discovered are:

• A snake that has a bright orange, almost flame-like, neck colouration that gradually fuses into an extraordinary iridescent and vivid blue, green and brown pattern. When threatened it flares its nape, revealing bright orange colours.
• A frog that breathes through its skin because it has no lungs, which makes it appear flat. This aerodynamic shape allows the frogs to move swiftly in fast flowing streams. Although the species was discovered in 1978, it was just recently that scientists found the frog has no lungs.
• A high-altitude slug found on Mount Kinabalu that has a tail three times the length of its head. They shoot calcium carbonate "love darts" during courtship to inject a hormone into a mate. While resting, the slug wraps its long tail around its body.

The Heart of Borneo, the core island area the conservation effort targets, is home to 10 species of primate, more than 350 birds, 150 reptiles and amphibians and a staggering 10,000 plants that are found nowhere else in the world, the report says.

This snake, Dendrelaphis kopsteini, is one of the recent discoveries from Borneo. When threatened it flares its nape, revealing bright orange colours against a background of vivid blue, green and brown. (Gernot Vogel/World Wildlife Fund/Associated Press)