November 4, 2019 6:18:24 pm
The discovery of a new species, one would imagine, involves trekking into deep forests, miles away from human habitation.
But in a world where forest cover is fast depleting, such discoveries can be closer home. Quite literally. A telling example is that of a new frog species found in a residential area of West Bengal.“In plain sight, in a residential area!” says Jayaditya Purkayastha, part of the team that discovered the amphibian.
While Purkayastha is a Assam-based herpetologist and runs conservation NGO Help Earth, the frog was found in two places in the neighbouring state of West Bengal — Badu, North 24 Parganas District and Khordanahala, South 24 Parganas District. The location has inspired the name of the discovery — Polypedates bengalensis, or the Brown Blotched Bengal Tree Frog belonging to the genus Polypedates — and has now been recognised by Zootaxa, a peer-reviewed international journal.
“Many researchers, drawn towards only pristine and wild areas, often skip urban and semi-urban areas. As a result, one tends to miss such discoveries. This frog has been in plain human sight for god knows how long, and yet it wasn’t discovered,” says Purkayastha. The conservationist, who works primarily with turtles, often receives pictures of frogs, snakes and other reptiles on Whatsapp from people around and even beyond Northeast India, with requests to identify them.
The first picture of the Polypedates bengalensis came to him in late 2016 from Shibajee Mitra, a snake enthusiast in Kolkata. “The moment I saw it then, I knew there was something different about the frog,” says Purkayastha. Frogs of the genus Polypedates — a genus of tree frog found throughout South and Southeast Asia — usually have stripes but not blotches like this one had. “And they are usually yellow, but this one was yellow and brown. I got excited. In taxonomy, the moment we see something even a little different, we are always hopeful that it is something new altogether.”
However, it took Purkayastha nearly two more years for the actual examination to begin. It was only when Kingshuk Mondal, another reptile enthusiast from West Bengal, sent him more photos, collected a sample of the species, and recorded its call, that some serious scientific headway was made. “What was interesting was the call of the frog, which could be “heard well after sunset and continued till after midnight.” While we depend a lot on molecular studies now, in the past, the call was the most important criteria to differentiate between closely related species. This one had a distinct ‘tok tok’ sound,” he explains, adding that this species also had “a continuous series of 6–9 dark brown blotches extend laterally from behind the eye to vent.”
There are 25 other Polypedates species (Polypedates bengalensis is the 26th) around the world. The researchers also coordinated with Indraneil Das of University of Malaysia, known for discovering several other species of Polypedates before. In India, Anirban Chaudhuri of the Wildlife Conservation Society and Guwahati-based Madhurima Das helped in coordination of the project and genetic determination of the frog, respectively.
There are more than 410 frog species in India. The discovery of the Brown Blotched Bengal Tree Frog while hopeful also points to how vulnerable species are in non-protected areas. “Unless you protect the area, species will get lost quickly. On the plus side, we hope that this discovery leads to some visibility of this specific area, and other such areas too. It will give a much-needed boost to the field of urban biodiversity as a whole,” he says.
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