A thumb-sized “living fossil” frog that has remained hidden for millions of years has been discovered on a remote mountain range in India.
The starry dwarf frog is a camouflage expert, plunging into leaf litter and blending invisibly into its surroundings when disturbed.
Not only is the species new to science, it is the sole survivor of an ancient frog lineage stretching back millions of years that has evaded discovery until now.
Experts named the frog Astrobatrachus kurichiyana in recognition of its star-like markings and the indigenous people from the hill range where it was found.
Dr David Blackburn, from the Florida Museum of Natural History, US, a member of the team behind the discovery, 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.”
The amphibian, dark brown with a bright orange underbelly, is speckled with pale blue dots giving the impression of stars.
Scientists stumbled onto the frog during a series of expeditions to the Western Ghats, a 1,000 mile-long mountain range along India’s south-western coast that is one of the world’s richest biodiversity hotspots.
It was almost overlooked among 30 different species of frogs, lizards and snakes captured and photographed in one night.
The next morning expedition leader Dr Seenapuram Vijayakumar, from George Washington University, US, spotted another of the frogs nestling in grass.
“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 realise it would become so interesting.”
Years passed before a team could be assembled to examine the frog in detail and describe it.
The results are published in the journal PeerJ.
Scientists in the US analysed the creature’s genetics and used CT scanning to look at its skeleton.
They found that A. kurichiyana was from a previously unknown frog sub-family whose nearest relatives belonged to a group of nearly 30 species native to India and Sri Lanka.
Their last common ancestor was thought to date back tens of millions of years.
The starry dwarf frog still holds onto secrets.
Scientists still do not know its life cycle, the sound of its call, or whether it is threatened or endangered.
Dr Vijayakumar said: “These frogs are relics. They persisted so long.
“This lineage could have been knocked off at any point in time.
“Irrespective of who we are, we should be celebrating the very fact that these things exist.”