Dusk descended slowly in tones of grey and ink blue: just what wildlife biologist Robin Abraham and his team were waiting for. It was dark in the freshwater swamp they were standing in, under the dense canopies of enormous evergreen Myristica (native nutmeg) trees. Water trickled quietly under a mesh of half-foot-high aerial Myristica roots. Flicking off leeches and swarming mosquitoes, and undistracted by the strong, muddy smell of wild elephants in the vicinity, the team combed the drenched ground and bushes with a torch for some rather under-appreciated denizens of these forests—frogs.
And then they heard it: a call they had never heard before. Trk...trrrrrr. Trk...trrrrrr. A faint call from a low-hanging vine.
The team huddled in excitement: a roughly 5 cm long, rust-brown arboreal frog with little bulbous toe tips and yellow-tinted eyes. It was not a particularly unusual looking tree frog, but it exhibited some rather unique behaviour. Just before mating, for instance, male and female frogs descend to the ground and changed colour to match leaf litter. Rather than laying eggs in water as most frogs do, these choose shallow burrows. Their interest piqued, the team used genetic analysis and confirmed the species was distinct enough to warrant a name of its own. They called it— Mercurana myristicapalustris —after the Myristica swamps they inhabit in the southern Western Ghats of Kerala (and, curiously, also after singer Freddie Mercury).
Fejervarya neilcoxi.
Taxonomy resurrected
Mercurana is just one of a staggering 130 new amphibians that have been discovered in the Western Ghats since the year 2000. Of India’s 405 amphibians—including frogs, toads, caecilians (limbless amphibians) and salamanders—239 are found in the Western Ghats, a 150 million-year-old mountain range that hugs the country’s western coast. Just last month, a team of batrachologists (frog biologists) from Delhi University, lead by Sathyabhama Das Biju, added four more to this list: the Manoharan’s, Kadar, Neil Cox’s and CEPF Burrowing Frogs.
So why the sudden spurt in new discoveries from this mountain range? The reasons are many. In the past, physical characteristics were all that many biologists used to rely on to identify species, with the result that many were labelled wrong. Advances in science today have ensured that detailed and comparative studies of frog genes, behaviour, calls (a field of study known as bioacoustics) and physical characteristics are possible.
“Integrating molecular [genetic], morphological and behavioural methods of study has increased accuracy in identifying species better,” says Biju. His team has identified more than 80 new amphibians in India. Only if new species are markedly different from closely-related species and existing, higher taxonomic groupings (such as genus and family) are they assigned to new genera and families. Biju’s team has discovered one new family, Nasikabatrachidae , which comprises the purple or pig-nosed frog, and four genera that are found only in the Western Ghats.
This resurrection of amphibian taxonomy has been crucial, says Abraham. “Better access online to type specimens of previously described taxa in open access forums such as the Biodiversity Heritage Library and Archive.com has also helped,” he adds. Also, while field studies in the past took place only during the day, most researchers today do not hesitate to work at night, which is when amphibians are active. “Observing breeding habits [in the wild] and documenting life-histories of various amphibian species has helped identify crucial behavioural differences,” says Abraham. “Technology and gear that we use to study frogs in field are incomparable to what we had 20 years ago,” says batrachologist Gururaja K.V., faculty at the Srishti Institute of Art, Design and Technology in Bangalore, Karnataka.
Fejervarya kadar.
However, not every species described today is necessarily new, cautions Abraham. “We demonstrated that the recently described Raorchestes emeraldi , for instance, is the already-known Raorchestes flaviventris , which was described 132 years ago. Similarly, other recently described species would also warrant critical examinations.”
What’s in a name?
But how do these discoveries matter? Discerning taxonomic status is the crucial first step to understanding amphibian ecology and evolution better. “It helps us ask more detailed questions, which can be vital for conservation,” says Gururaja. These include aspects of species ecology including frog behaviour. It was Mercurana’s unique egg-laying behaviour, for instance, which raised doubts that it could be a different species, and not the commonly-found one it resembled. “It is important to see how traits such as parental care and related behaviour evolved because it tells us how frogs adapt to their surroundings; and in turn helps us see how they can adapt to changing climates,” he adds.
“Negative effects of anthropogenic climate change are very likely,” says Abraham. “Studies to understand their effects on amphibian life-histories is vital.” Being restricted to small areas or ‘microhabitats’, even small changes in temperature could sound the death knell for frogs. But currently, it is habitat loss that is the most pressing concern. Many new frog species are found outside protected areas and in human-dominated ones, including in backyards. Two of the new species discovered by Biju’s team—the Kadar and CEPF Burrowing Frogs—could be facing serious anthropogenic threats and may require immediate conservation attention. Similarly, the Myristica swamps of Kerala that are home to Mercurana are one of the most threatened ecosystems in the Western Ghats.
A combination of amphibian taxonomy, ecology and evolution is crucial not just for conservation but also to understand the role of frogs in the ecosystem. “Amphibians are natural pest control agents and bioindicators,” says Gururaja. High insect populations could decimate crop produce and affect humans directly, but frogs keep them under control. Amphibians also have porous skin, which means that any pollution in the local ecosystem will affect them first: thus they are great bioindicators and reflect the health of an ecosystem. But these roles have often been overlooked.
There has been more focus on charismatic species, and frogs and other smaller life forms have been ignored. But attitudes towards amphibians seem to be shifting. “There is an increased enthusiasm towards studying frogs now. Complacency is not a luxury for batrachologists; every frog you see may be a new species,” says Gururaja.
