A new species of carnivore has been discovered in Madagascar, conservationists have said.

The cat-sized, speckled-brown mammal belongs to a family of mongoose-like animals found only on the island nation and is probably one of the most threatened carnivores in the world, researchers said.

The species, named Durrell’s vontsira (Salanoia durrelli), was identified by researchers from the Durrell Wildlife Conservation Trust, the Natural History Museum, Nature Heritage and Conservation International.

The animal was first spotted swimming in a lake by a team from the Durrell Wildlife Conservation Trust in 2004 while they were surveying bamboo lemurs.

After briefly examining the animal, the team suspected they had found a new species and took photographs of it.

Subsequent analysis of specimens of another species, the brown-tailed vontsira, in the Natural History Museum’s collections, showed that they had found a new species.

It is the first new species of carnivorous mammal to be discovered in 24 years.

Fidimalala Bruno Ralainsasolo, a conservation biologist working with Durrell who originally captured the new carnivore in the lake, said: “We have known for some time that a carnivore lives in the Lac Alaotra marshes, but we’ve always assumed it was a brown-tailed vontsira that is also found in the eastern rainforests.

“However, differences in its skull, teeth and paws have shown that this animal is clearly a different species with adaptations to life in an aquatic environment.

“It is a very exciting discovery and we decided to honour our founder, the world-renowned conservationist Gerald Durrell, by naming this new species after him.”

But the conservationists warned the animal’s habitat of the Lac Alaotra marshes, where the Alaotra grebe has recently been declared extinct, is highly threatened by agricultural expansion and pollution, burning and invasive plants and fish.