The species Paucidentomys vermidax found on the Indonesian island of Sulawesi is 'unique' among rodents as it has no chewing molars, the Daily Mail reported.
The creature has fang-like upper incisors which are useless for gnawing and no back teeth.
It lives exclusively on earthworms which it sucks out of the ground at the foot of the jungle with its long snout.
"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," Dr Kevin Rowe, from Museum Victoria in Australia, a member of the discovery team, said.
"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," Rowe was quoted as saying by the paper.
The creature has a rat-like tail but a long, thin nose. Its only teeth are its incisors, which in the upper jaw end in twin points.
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"The specialised incisors of rodents give them the distinct ability to gnaw - a defining characteristic of rodents worldwide," co-author Anang Achmadi, from Museum Zoologicum Bogoriense in Indonesia, said.
"In having lost all teeth except a pair of unusually shaped incisors that are incapable of gnawing, this new rat is unique among rodents," Achmadi added.
The discovery was published in the Royal Society journal Biology Letters.