The shrew-like animal, Paucidentomys vermidax, has fang-like upper incisors which are useless for gnawing and no back teeth. It lives exclusively on earthworms.
A newly discovered 'toothless' rat species represents a new step in rodent evolution
P. vermidax was found in remote rainforest on the Indonesian island of Sulawesi.
It shares some characteristic with insectivorous shrew rats from the Philippines but has taken an evolutionary step further by completely dispensing with chewing molars.
Dr Kevin Rowe, from Museum Victoria in Australia, a member of the discovery team, said: "There are more than 2,200 rodent species in the world and until this discovery all had molars in the back of their mouth and incisors at the front.
"This is an example of how species, when faced with a new ecological opportunity, in this case an abundance of earthworms, can evolve the loss of traits that were wildly successful in previous circumstances."
P. vermidax is described in the latest issue of the Royal Society journal Biology Letters.
The creature has a rat-like tail but a long, thin nose similar to a shrew's. Its only teeth are its incisors, which in the upper jaw end in twin points. The Latin derived genus name Paucidentomys means "few-toothed mouse" and the species name vermidax means "devourer of worms".
Co-author Anang Achmadi, from Museum Zoologicum Bogoriense in Indonesia, said: "The specialised incisors of rodents give them the distinct ability to gnaw - a defining characteristic of rodents worldwide. In having lost all teeth except a pair of unusually shaped incisors that are incapable of gnawing, this new rat is unique among rodents."
Dr Rowe said the find was a reminder that wild habitats can still harbour undiscovered species.
Article courtesy of Yahoo News