Aussie scientists discover new mammal the ‘slender rat’ on Indonesian island

A new and unique mammal discovered on the Indonesian island of Sulawesi has been named the slender rat.

Aussie scientists were part of the international team that made the discovery on the slopes of a remote mountain, Museum Victoria advised.

The slender rat, whose scientific name is Gracilimus radix, forages among the roots of trees and had not been previously documented in any scientific collections.

With anatomy so unique, the rat has been described as a new genus, which the museum said is a "step above a new species in the taxonomic rank".

The rat is most closely related to the carnivorous Sulawesi water rat, which was described by the same team in 2014.

However, it appears to be omnivorous, Museum Victoria's Dr Kevin Rowe said.

"The differences between Gracilimus radix and its closest relative, the water rat, Waiomys mamasae, are astounding; one has evolved for swimming and one for life on land, yet in evolutionary terms they are sisters," he said.

The slender rat is the third genus and fourth new species discovered by the same team on Mount Gandangdewata in the past four years.

Last year, the hog-nosed rat was discovered.

The discoveries demonstrate the island’s great value in terms of biodiversity, Dr Rowe said.

Sulawesi has no formal protection by the Indonesian government, but its forest have been protected by the local Mamasa people for generations, the museum said.

"Sulawesi Island is a global biodiversity hotspot and the location of this discovery, Mount Gandangdewata, is one of the hottest areas for diversity on Sulawesi," Dr Rowe said.

"It contains the largest continuous tract of old growth forest left on the island which is home to at least 27 species of rodent – twice what we see elsewhere on the island."

Other members of the team that made the discovery are Museum Zoologicum Bogoriense's Dr Anang Achmadi and the Louisiana State University Museum of Natural Science's Dr Jacob Esselstyn.

Dr Achmadi will return to the mountain to conduct a survey and prepare a formal report aimed at stating the case for formal conservation, which will be handed to the country's forestry department.

The team's research on the new discovery will also be published in the next edition of the Journal of Mammalogy.