Scientists have found 12 new species of night frogs living in the lush mountains of south-west India, and rediscovered three that had been thought extinct.
Evolution biologist Sathyabhama Das Biju, from the University of Delhi, said he hopes the discoveries draw attention to amphibians as important indicators of environmental health.
He said that there are now 336 known frog species in India, and that many are threatened by habitat loss.
Night frogs are hard to find as they come out only after dark and during the monsoon season.
Mr Biju and student researchers had to sit in dark tropical forests listening for frog sounds and shining torches under rocks and across riverbeds.
The research is published in the latest issue of international taxonomy journal Zootaxa.