A tiny thumbnail-sized new frog species has been discovered in India’s Western Ghats, a ‘hotspot’ for amphibian discoveries.
The frog’s constellation-like markings makes it an exceptionally good camouflager among the wet leaves of its habitat.
This may explain why it has escaped notice for so long, say scientists.
The new species is the only member of an ancient lineage that goes back tens of millions of years and also represents the discovery of a new subfamily.
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A tiny thumbnail-sized new frog species has been discovered in India’s Western Ghats. The frog was named Astrobatrachus kurichiyana, after the ‘starry’ constellation-like markings on its body and the indigenous people of the Kurichiyarmala hill range that it inhabits
The new species has been named Astrobatrachus kurichiyana, after its ‘starry’ body markings and the indigenous people of the Kurichiyarmala hill range where it was found.
The frog is not only a new species, its family tree it also represents a new subfamily that has been classified by scientists as Astrobatrachinae.
Dr David Blackburn, the associate curator of herpetology at the Florida Museum of Natural History who led on the latest study of the frog, said: ‘This is an oddball frog – it has no close sister species for maybe tens of millions of years.’
‘With frogs, there are still ancient lineages out there awaiting discovery. This gives us one more puzzle piece to think about deep time.’
Only a handful of the new species has been found in the a 1,000-mile-long mountain range along India’s southwestern coast, a challenge given its camouflaging skills, say researchers.
The frog has distinct pattern made of a dark brown body speckled with pale blue dots and a bright orange underbelly that allows it blend stealthily with wet leaf litter.
Dr Seenapuram Palaniswamy Vijayakumar, lead author of the study and postdoctoral fellow at George Washington University, said: ‘The coloration was the first thing that stood out to me, these starry patterns with a blue tinge.
‘We hadn’t seen anything like this before.’
The frog is not only a new species, its family tree it also represents a new subfamily that has been classified by scientists as Astrobatrachinae
The dwarf frog nearly got overlooked in the pile of new species discoveries that Dr Vijayakumar and his then supervisor Dr Kartik Shanker made during their expeditions to the Western Ghats some years ago.
Dr Vijayakumar and Dr Shanker, associate professor at the Indian Institute of Science, designed a meticulous study, covering multiple elevations, habitats and hill ranges to record and map the region’s frogs, lizards and snakes.
‘When we started sampling, we realized we were digging up a huge treasure,’ Dr Vijayakumar said.
This was one among 30 species we captured one night, and while I took photos of it, none of us paid much attention to it.’
The next morning, on a chilly, wet stroll over the grasslands – watching the ground for leeches – Dr Vijayakumar spotted another of the unusually patterned frogs.
‘I picked it up and said, ‘Hey, this is the same guy I photographed in the night,” he said. ‘As a greedy researcher, I kept it, but at that point in time, it wasn’t too exciting for me. I didn’t realize it would become so interesting.’
The latest study from US researchers, years after scientists in India first visited the West Ghats mountain range, examined both the genetic makeup of the new species through DNA sequencing and CT scanning that revealed its skeleton and other internal features
The latest study from Dr Blackburn and colleagues in the US, years after the scientists from India first visited the mountain range, analysed the frog’s genetics and CT scanned the frog, revealing its skeleton and other internal features.
Dr Blackburn added: ‘I’ve never physically seen this species we’ve put all this effort into describing.
‘Once specimens are digitised, it really doesn’t matter where they are. The strengths that Ed and I could contribute to the team – comparative anatomy – were things we were able to do digitally.’
The researchers compared the starry dwarf frog’s bone structure to other frog species from the Western Ghats that have been imaged as part of the openVertebrate project, known as oVert, an initiative to scan 20,000 vertebrates from museum collections.
The area of Western Ghats in India is a ‘hotspot’ for frog discoveries, and its creatures are among the smallest in the world. New species of found in recent years include the Vijayan’s Night Frog (pictured) which are tiny enough to fit on a fingernail
Florida Museum associate scientist Dr Edward Stanley, who took the CT scans, said: ‘We have this deep bench of CT data that makes collections amassed over hundreds of years instantaneously available, not just to researchers, but to anyone with a computer’.
The team found that the frog’s closest relatives are the family Nyctibatrachidae, a group of nearly 30 species native to India and Sri Lanka.
But their last common ancestor could date back tens of millions of years.
‘These frogs are relics. They persisted so long. This lineage could have been knocked off at any point in time,’ Vijayakumar said. ‘Irrespective of who we are, we should be celebrating the very fact that these things exist.’
Scientists have found many ancient lineages of frogs in the Western Ghats, whose biodiversity stems from its history and distinct geography.
India, once part of Africa, split from Madagascar about 89 million years ago and drifted northeast, eventually colliding with the Asian mainland and giving rise to the Himalayas.
But its long isolation as an island provided fertile ground for the evolution of new life forms and may have sheltered species that disappeared elsewhere.
WHAT IS GENOME SEQUENCING?
It is the process of determining the complete DNA sequence of an organism’s genome at a single time.
A genome is an organism’s complete set of genetic instructions written in DNA.
Each genome contains all of the information needed to build that organism and allow it to grow and develop.
With advances in technology and falling costs of sequencing, scientists are able decipher these sequences with increasing speed.
They can be used to show the evolution of an organism and how it changed over time.
This is especially true of the Western Ghats, which is much like a network of islands, Vijayakumar said. The elevated region has been cross-sectioned into separate hill ranges by millions of years of erosion and climatic changes.
‘It’s a perfect scenario for cooking up new species,’ he said.
One question he and Blackburn are interested in exploring further is whether peninsular India’s frogs are the descendants of African ancestors or whether they first originated in Asia and then moved south.
Finding ancient lineages like Astrobatrachinae can help fill in in the region’s distant biological past, but the starry dwarf frog maintains many mysteries of its own.
Researchers still do not know its life cycle, the sound of its call or whether the species is threatened or endangered.
Dr Vijayakumar said when study co-author Dr K.P. Dinesh of the Zoological Society of India returned to the hill range where the frog was first found, ‘he searched the whole forest floor and hardly saw any individuals. This frog is so secretive. Just one hop into the litter, and it’s gone.’
The past decade has seen a huge increase in the number of new amphibian species described from the region of Western Ghats.
Of the 1,581 new species of amphibians found globally in 2006-2015, the highest number were from the Brazilian Atlantic Forest, followed by the Western Ghats-Sri Lanka biodiversity hotspot, with 103 species described alone from the Western Ghats region.