New Delhi, Feb. 16: A flourescent green frog with ash-blue thighs and black pupils with patches of gold last observed 136 years ago is among five lost amphibians from India rediscovered by zoologists.

The zoologists from several academic institutions searching India’s forests for amphibians documented in the past but unseen for decades have rediscovered five frogs, including the Chalazodes bubble-nest frog last reported from Travancore in 1874.

“It’s got a colour combination I have never ever seen in 27 years of studying amphibians,” said Sathyabhama Das Biju, a zoologist at Delhi University, who is also the coordinator of the nationwide search for lost amphibians.

The Indian effort was part of a search for missing amphibians in 21 countries launched in August last year by the non-governmental body Conservation International and the International Union for Conservation of Nature.

Biju and two Bangalore-based conservation researchers R. Ganeshan and K.S. Seshadri found the Chalazodes bubble-nest frog in the forests of Kodayar near the Kalakkad Tiger Reserve in Tamil Nadu on a November night.

As they walked in the dark with torchlights using sticks to lift clumps of bushes, they were drawn to a cluster of bamboo reeds by the call of what sounded like a frog. A few minutes later, they spotted it on the reed about five feet above the ground.

“It is a secretive animal — it spends most of its time hiding inside the bamboo reeds. It comes out during breeding but lays eggs inside the reeds,” Biju told The Telegraph. The scientists observed one juvenile and three adults.

A British herpetologist had documented the species from Travancore in 1874, Biju said. Scientists believe this frog does not have a free-swimming tadpole stage, but completes development inside the egg.

The amphibian search has also yielded the Anamalai dot frog, the Dehradun stream frog, the Silent Valley tropical frog, and the Elegant tropical frog — each of which had last been observed decades ago and were classified as missing.

“Our knowledge of what we have to conserve is poor. Searching for lost species is an important step towards understanding what we have left to conserve. If we want to save frogs, we first have to find them,” Biju said.

Scientists have been concerned about what appears to be a global decline in the population of amphibians. The 21-country search looked for 100 missing amphibians. It succeeded in finding only four of the 100 missing amphibians. However, it led to the rediscovery of the five amphibians from India and the rediscovery of six frogs in Haiti, including one named Mozart’s frog last seen in 1991.

“Rediscoveries provide reason for hope for these species... but the vast majority of species that teams were looking for were not found,” said Robin Moore, an amphibian expert at the Washington DC-based Conservation International.

Amphibians are important to humans — they eat and control populations of insects that spread disease to humans or damage crops, and they help maintain healthy freshwater ecosystems, according to Conservation International. The chemicals in amphibian skins have been used in the search for new candidate drugs, including one molecule that seems to be 200 times more potent than morphine, it said.

Biju and his colleagues from the Indian Institute of Science, Bangalore, the Zoological Survey of India, and other institutions plan to continue the search for missing amphibians in northeastern India in the coming months.