A chestnut brown snake with white and black streaks sits coiled up on a dirt floor.

The new species has been named Joseph's racer, Platyceps josephi, after a late colleague of the researchers ©Surya Narayanan 

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New species of snake described with the help of a 185-year-old painting

A new snake species has been described from the Indian state of Tamil Nadu.

Now known as Joseph's racer, the new species was first collected in the mid-nineteenth century. But confusion around this snake goes back over two centuries as it had been mixed up with another similar species found across the rest of India. 

The discovery started when in 2016 a colleague of Museum associate Dr Deepak Veerappan collected a snake from Tamil Nadu that looked different from the widespread species normally thought to be found in the area.

A quick assessment of the reptile, looking at both its morphology and genetics, confirmed it was likely a new species to science.

But little did Deepak and his colleagues know that they'd just pulled at a thread that would unravel a mix-up of snake species that stretched back some 200 years.

'This new species isn't like other new species that are described, because it has a very checkered past in terms of the literature,' explains Deepak. 'Since it is so widespread, many people have studied these snakes and given them lots of different names.

'But one of the biggest problems is that the names between two of the most common species of snakes found in India have been frequently confused.'

This confusion can be traced back to a scientist called Albert Günther, who worked at the Museum between 1875 and 1895. It was Günther who first mixed up the two species and for the following 150 years people have just continued to follow this without questioning it.

'It wasn't easy to discover this,' says Deepak.

The full paper is published in the journal Vertebrate Zoology.

A tangle of snakes

The species of snake that has caused all this confusion is the banded racer, previously known as Argyrogena fasciolata. The description of this species was, in part, based on snake skins collected in 1796, which are now in the Museum's collections.

This gave Deepak the extraordinary chance to go back to these original collections and reassess the snakes. 

A painting of a snake along with a nest of its elongated eggs.

The beautiful paintings from 185 years ago were so detailed that they allowed Deepak and his colleagues to use them in the description of the new species. Source: Library and Archives, Natural History Museum, London

But what Deepak found showed just how much of a tangle there was surrounding these old descriptions. None of the skins collected in 1796 were from the banded racer, but instead belonged to a completely different species called the wolf snake.

'It took a while for us to untwine this whole thing,' explains Deepak. 'It would have been impossible without the snake skins collected by Patrick Russel, who was a Scottish naturalist based on the east coast of India in the late 1700s.

'When I measured all of them we realised that they were all too small, and none of them matched the racer description.'

Following the thread through history brought Deepak and his colleagues to a series of natural history paintings produced in 1836 by a Danish physician and zoologist named Theodore Cantor.

Cantor was working for the British East India Company, during which time he used this position to become the first western scientist to collect and scientifically describe many species, including the Siamese fighting fish and king cobra. 

He also collected paintings of many of these animals, including snakes. The paintings are now held at the Museum (B.H. Hodgson's collection) and the Bodleian Library in Oxford (Cantor's collection)., which allowed the team to study the pictures in exquisite detail.

These paintings are so detailed that even the number of scales on the snake's heads can be counted, which can be used as a way to tell species apart.

It turned out that some of the snake paintings drawn 185 years ago were misidentified. By comparing them with actual specimens the painted snakes were eventually identified as banded racers, and played a key role in resolving the confusion and helped in describing the new species.

A  brown snake with a lighter, cream underbelly and balck eye sits coiled on the ground.

The original banded racer is now known as Playceps plinii, and can be found throughout much of India ©Pratyush Mohapatra

After wading through the rest fof the literature surrounding the banded racer, including reassessing over 400 different accounts of the snake, Deepak and his team confirmed that the racer was not just a single species as had long been thought.

Two species out of one

The original banded racer is now known scientifically as Platyceps plinii. This is the most common racer species found across much of India and has been given a new scientific name as through all this research they even found it to belong to a different genus.

It also helps to clear up all previous confusion that has arisen from a huge range of different names being given to the one snake. 

The new species is now known as Joseph's racer, Platyceps josephi. The species has been found to have a much more restricted distribution, found only in the south-eastern state of Tamil Nadu, which may have an impact on the snake's conservation.

'They live in dry savanna-like habitats,' explains Deepak. 'You could even go so far as to say in some areas it is semi-arid desert because there are not even small trees, just dry scrub.

'The Joseph's racer is not particularly common. We have given a recommendation based on their distribution and the data available that it is most likely a Vulnerable species because of its restricted distribution.'

This work highlights the importance of clearing up these historical muddles, as researchers now know that the species from Tamil Nadu is different and could face threats to its continued survival.

It also shows just how important all aspects of collections are. The work relied not only on specimens of snakes in jars, but also skin collections made 225 years ago and paintings held in the library, all combining to clear up one issue of taxonomy.