Subscribe
In a surprising discovery, scientists have identified two frog species native to Sri Lanka thriving in a mountain range in India. The Sri Lankan golden-backed frog (Hylarana gracilis) and Sri Lankan shrub frog (Pseudophilautus regius), previously unknown from India, were found in the Eastern Ghats.
A team of researchers from Zoological Survey of India (ZSI) and the Andhra Pradesh Biodiversity Board made the discovery.
The two amphibians are not new species, but their presence in the Eastern Ghats sheds light on the region's ancient connection to Sri Lanka. The researchers believe the frogs may have dispersed roughly 10,000 years ago, when a land bridge with forests existed between the Indian mainland and Sri Lanka.
Geological events like fluctuating sea levels and changes in monsoons likely isolated these frog populations, leading to their disjunct distribution today, with a gap of nearly 700 kilometres between their known habitats.
The Sri Lankan golden-backed frog lives in freshwater, whereas the Sri Lankan shrub frog develops directly. In a directly developing frog, an adult produces eggs that hatch into young ones who grow into adults without passing through the tadpole stage of development.
K P Dinesh, a scientist involved in both studies, stated that both findings are significant from a biogeographic and evolutionary perspective.
“The golden-backed frog was discovered from Sri Lanka in 1829 and commonly found in that country. After nearly two centuries, the same freshwater-associated frog (genetic divergence of 0.2 to 1 per cent) has been rediscovered in India’s Eastern Ghats,” he said.
Despite unconfirmed reports of the species in the region, deoxyribonucleic acid (DNA) barcoding revealed genetic evidence that matches its Sri Lankan counterpart.
The Sri Lankan Shrub Frog, on the other hand, was first discovered in Sri Lanka in 2005. Almost two decades later, the species has been discovered at an aerial distance of 700 km in India's Eastern Ghats.
The studies genetically confirm the same species from both countries, with variations in morphology such as colour and minor genetic differences.
“The unique aspect of the frog is that a conventional amphibian life cycle stages include eggs, free-swimming tadpoles, semi-terrestrial young ones (imago) and land-living adults, but species of Brown-eared Shrub Frogs are ‘direct developing’, which means there is no free-swimming tadpole stage in this group of frogs and miniature adults emerge directly from eggs,” Dinesh said.
Sri Lanka has 75 shrub frog species, whereas India's Western Ghats only have three. The authors stated that all species are endemic to their respective landscapes.
At present, the Eastern Ghats are known to have 28 amphibian species, compared to 253 documented species in the Western Ghats and 455 species throughout India. The discovery of amphibians in the Eastern Ghats adds value to the region because they are considered ecological indicators of a pristine and healthy ecosystem.
India has 19 species of golden-backed frogs, 11 of which are endemic to the country. The new discovery represents the 20th species of freshwater.
In a press release, lead author Bharath Bhupathi stated that the frog species was discovered next to a pond in the forest and was thought to be a new species. However, morphological and DNA barcoding confirmed the species as Sri Lankan golden-backed frog.
Dhriti Banerjee, director of ZSI, stated the discovery supports historical sea level changes that occurred during the late Pleistocene period (nearly 2 million years ago), when land between India and Sri Lanka was connected and amphibians migrated.
