An exceptional biodiversity hotspot in Africa has yielded yet another new species of mammal. The giant elephant shrew, found by accident in the dense forests of central Tanzania's Udzungwa Mountains, is the first such mammal to be discovered in more than 126 years.

Elephant shrews (not related to true shrews) – or sengi – are a small group of unusual African mammals distantly related to elephants, sea cows and aardvarks.

In 2002, Galen Rathbun, a behavioural ecologist and sengi expert at the California Academy of Sciences in San Francisco, US, received an email from a biologist claiming to have seen a sengi unlike any known species.

Rathbun was dubious. "Visual observations of an animal that runs like the wind in the deep forest are often dicey," he told New Scientist. "I get several a year. So I kind of put it in the back of my mind."

Camera traps

But then in 2005, Francesco Rovero of the Trento Museum of Natural Sciences in Italy, sent him clearer evidence. Rovero had set out automatic camera traps in the Udzungwa Mountains to monitor small antelope known as duikers, and these cameras had captured images of the purported new sengi.

That persuaded Rathbun to see for himself, and he and Rovero mounted an expedition in March, 2006.

Within half an hour of entering the forest, the researchers came across a half-eaten specimen lying on the trail and knew they had discovered a new species. Over the next two weeks, they sighted 40 live individuals and collected four other specimens.

The new sengi, named Rhynchocyon udzungwensis, is about the size of a rabbit, weighing about 700 grams, with a long hairless nose, deep maroon-coloured fur ("the colour of a beer bottle", says Rathbun) and long, spindly legs.

Pristine habitat

Like other sengis, it eats ants, worms, and other small invertebrates on the forest floor, flicking them out of the leaf litter with its long tongue.

The new sengi is the fifth new mammal species – and at least the 25th new vertebrate – to be discovered in the Udzungwa Mountains in the last decade.

This makes the mountains a biodiversity hotspot almost unparalleled in Africa, says John Watkin, who oversees east African programmes for Conservation International, an environmental group based in Washington, DC, US, that helped fund Rathbun's expedition.

The Tanzanian government has set aside the entire mountain range as a protected area. "It's fairly pristine," says Rathbun. "It's not logged, it's not hunted heavily. But the human pressures in Tanzania are immense, so there's a lot of concern for the habitat."

Journal reference: Journal of Zoology