They are active at night and difficult to spot. They call from elevated branches or from under dense vegetation, making it very difficult to spot them.

However, a joint team of biologists from University College Dublin, Ireland, Natural History Museum, London, and University of Delhi have discovered four new species of horned frogs from the Northeast after 14 years of research.

“They are most easy to find after dusk because we can follow their vocal cues and shine torch to focus on our field of view. One of the most awesome experiences I had with horned frogs was finding the individual of the original Megophrys major. I heard its call from a distance of 700 metres. I knew that it was a big Megophrys male so I followed it carefully until I discovered it calling from a leaf behind leaves in a torrent hill stream. I was elated,” said Rachunliu G. Kamei of the department of life Sciences at Natural History Museum.

The scientists named the four new Indian species as the Himalayan horned frog (Megophrys himalayana), the Garo white-lipped horned frog (Megophrys oreocrypta), the yellow spotted white-lipped horned frog (Megophrys flavipunctata) and the giant Himalayan horned frog (Megophrys periosa).

The four species were found at different places in Arunachal Pradesh, Meghalaya and Nagaland.

The discovery is the result of scholar Stephen Mahony’s PhD research, carried out under the supervision of Emma Telling and S.D. Biju, professors of University College Dublin, Ireland, and University of Delhi, respectively. “Megophrys is a group of frogs that are widely distributed in tropical Asia. The group comprises a of total 83 species. In India, there are 16 Megophrys species, including the four new ones found in the region and in Bengal,” Biju said.

“They have unique fleshy horn-like projections on the upper eyelids. Megophrys frogs are primarily forest dwellers and are usually found in and around streams. These frogs breed in water and have unique tadpoles with a funnel-like mouth,” he added.

The study was published as a monograph in the scientific journal, Zootaxa.

Mahony said the discovery was made when the biologists were investigating a group of six closely-related species of horned frogs that are poorly known scientifically and have been subject to over 150 years of extensive confusion about its identities. The four new frogs were once thought to be a single wide-ranging species called Jerdon’s white-lipped horned frog that was considered to be found from the mountains of the Northeast.

However, after taking a closer look at this large forest frog, and using DNA analyses, the scientists discovered that it actually represents a bunch of species that superficially look quite similar but differ in some subtle ways. They are also genetically distinct and found in different regions.

“Our discovery highlights the need to carry out systematic research in the Northeast India to fully understand and conserve its unique frog fauna,” Biju said.