A Thumbnail-sized frog discovered

A research team has discovered a new frog species in the Western Ghats mountain range along the west coast of India. On a night stroll through a ‘shola’ forest fringed by high grasslands, the researchers from Indian Institute of Science (IISc) Bangalore spotted the thumbnail-sized frog sitting next to a leaf litter.

“At first glance, its bright orange belly, light blue starry spots on the sides of the body and triangular fingers set it apart from other frogs in the forest,” K. P. Dinesh, one of the researchers, now at the Zoological Survey of India in Pune, told Nature India. The frog is an expert hider. It can hop into a leaf litter at the slightest disturbance, he said.

The researchers have named the frog Astrobatrachus kurichiyana – from the Greek ‘astro’ for star and ‘batrachus’ for frog, and kurichiyana after the Kurichiyan tribe of Wayanad district in Kerala, where the frog was found1.

“This frog is a unique and exciting new find,” said S. D. Biju, a zoologist from the University of Delhi in New Delhi, who is not involved with the research. This discovery, he said, once again highlights that the Western Ghats is an important biodiversity hotspot, especially for amphibians.

This, along with discoveries of other frog species, could help us understand the patterns of diversification among the Western Ghats frogs, Biju added.

The frog first came to light in 2010 when S. P. Vijayakumar, then a doctoral student at IISc, noticed and collected it from the forest. Closer inspection in the lab revealed that this frog didn’t match the shape, size and colours of other frogs from the Western Ghats. The researchers realised that they needed to study the frog’s genes and bone structure to reveal its identity.

They consulted US-based experts David Blackburn from the University of Florida for bone studies, and Alex Pyron at the George Washington University for genetic evolutionary history. A. kurichiyana’s relatives, they found, belong to the family Nyctibatrachidae, a group of more than 30 frog species native to India and Sri Lanka.

Genetic analysis revealed that the new frog possibly diverged from its nearest relatives about 60 million to 70 million years ago, making it one of the oldest lineages in the Western Ghats, says Kartik Shanker, co-author of the study. This dates back to a time when India, after parting company with Africa and Madagascar, drifted north-east as an island before colliding with the Asian mainland, giving rise to the Himalayas.

Such a long isolation as an island made India a fertile ground for the evolution of new life forms, sheltering species that disappeared elsewhere. One such hotspot is the Western Ghats, which, much like a network of islands, supported myriad life forms, including the newly discovered endemic frog species, the researchers said.

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