Last month, a study led by Delhi University’s department of environmental studies described a new genus of an old-world tree frog called Rohanixalus from the Andaman Islands, named after the Sri Lankan taxonomist Rohan Pethiyagoda.
Frogs of the new genus have a small and slender body ( about 2 to 3 cm long), a pair of contrastingly coloured lateral lines on either side, brown specks scattered throughout the upper body, and lay light green coloured eggs in arboreal bubble nests.
Among their many interesting behavioural traits are remarkable maternal care—the mother attends to the egg clutches until hatching and assists in the release of the tadpoles into water.
The identification of this new genus has created ripples in amphibian research and highlighted so much that is left to be discovered in the amphibian world. The research work was carried out by SD Biju, professor and researcher, Delhi University, along with a team of researchers from the Zoological Survey of India–Andaman and Nicobar Regional Centre, National Centre for Cell Science and scientists from Indonesia, China and Thailand.
Frogs are among most fascinating creatures because of their distinct croaks; their ability to camouflage, long leaps—more than 20 times their body length for some species; their bulging eyes and diversity in skin colour, texture and size. Most importantly, frogs are bio-indicators which essentially means they are extremely sensitive to pollution. Their abundance or decline can easily tell you if a wetland or water body is polluted or clean. Almost every child has a memory of following frogs in the monsoon, but such interactions are on the decline especially in urban areas because the number and diversity of frogs face a grave threat from habitat loss.
Based on an assessment by the International Union for Conservation of Nature (IUCN)t, among frogs and toads, 20 are critically endangered; 35 are endangered and 22 vulnerable. Over 260 species (includes all species) are either not evaluated or in data-deficient status according to Gururaja KV, adjunct scientist at the Gubbi Labs.
“This also indicates that for a majority of species we do not have any precise data on population size. And in the last 20 years, we have added over 200 new species to India’s list, which is about 40% of the total species in India,” he said.
Other estimates suggest that one in every three amphibian species is facing extinction with habitat loss being the primary risk to their existence. “All over the world, amphibians (frogs, salamanders and caecilians) are the most threatened group of vertebrates. One-third of all known amphibian species, or in other words one in every three species, are facing extinction threats. Yes, among the known threats, habitat loss is one of the major causes for amphibian decline worldwide. Other significant threats include climate change, chytrid fungus, and pollution,” said Biju.
Interestingly, despite the steep decline in their numbers and diversity, science is bringing to light fascinating new species of frogs every year in India. Over the last two years, a frog subfamily, many frog genera, and species have been discovered across many landscapes of the Western Ghats, which is a biodiversity hotspot on the Chota Nagpur Plateau, lowlands of the Andaman Islands and the Naga-Chin hills in the northeast.
“Last year, researchers discovered a new burrowing frog species, Sphaerotheca magadha, from a semi-urban agricultural habitat in Chota Nagpur Plateau. There was also the discovery of a new ancient subfamily, the starry frog (Astrobatrachinae: Astrobatrachus kurichiyana) from high elevation forests in the Kurichiyar hill range in the Western Ghats…Interestingly, there was also a new genus: the mysterious narrow-mouthed frog (Mysticellus franki) discovered in a road-side puddle from Camel’s Hump, a few km from the previous ancient frog. This year, researchers reported the discovery of an old lineage: Muduga leaping frog (Walkerana muduga) from the high elevation of Elivalmalai mountain north of Palghat Gap in the Western Ghats,” said Vijaykumar SP ecologist from Indian Institute of Science.