The discovery of the tailless burrowing caecilians was made by a team of international scientists led by Professor SD Biju from Delhi University, the Proceedings of the Royal Society of London reported.

The scientists conducted soil surveys at 238 sites, beginning in 2006.

The caecilians, said to superficially resemble earthworms, are one of the three categories of amphibians. They live hidden in the ground and are among the least explored orders of the amphibians.

“Scientists performed DNA analysis of the specimens and confirmed that it is an entirely new family,” Biju said.

The new family has been named Chikilidae and the new species, Chikila, derived from Garo, a tribal language spoken in the region.

Researchers estimate that the newly discovered caecilians evolved separately from other species of caecilians more than 140 million years ago.

The new family is of ancient lineage whose closest relatives occur in Africa, a relationship established hundreds of millions of years ago before India broke away from Africa and collided with Asia creating the Himalayan mountain range.

“The work is a significant contribution to the understanding of vertebrate evolution and biogeography,” Biju said.

Scientists also said the discovery highlighted north-eastern India as a poorly studied region likely to harbour additional ancient lineages of organisms found nowhere else on Earth.