New species of rat redefines rodents

22 August 2012

Title:Evolutionary novelty in a rat with no molars

Authors:Jacob A. Esselstyn, Anang Setiawan Achmadi, and Kevin C. Rowe

Journal:Biology Letters

Rat

Scientists have discovered an extraordinary species of rodent in Indonesia unlike any other on Earth. The almost toothless, worm-eating rat, described in Biology Letters this week, is unable to gnaw or chew.

The discovery of this new rodent illustrates how the process of evolution can lead to the loss of previously successful traits in species faced with new opportunities; in this case a rat who has lost the ability to gnaw or chew, due to an abundance of earthworms.

“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,” said Dr. Kevin Rowe, Senior Curator of Mammals, Museum Victoria, and member of the team of scientists who discovered the new species.

The scientific name for the new species Paucidentomys vermidax reflects its dental and dietary adaptations, Paucidentomys meaning “few-toothed mouse” and vermidax meaning “devourer of worms”.

“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,” explained Mr Anang Achmadi, Curator of Mammals at Museum Zoologicum Bogoriense, and research colleague of Dr Rowe.

“While we face a global crisis of biodiversity loss, this new species reminds us that we are still in an age of biodiversity discovery. Wild habitats where new species wait to be discovered are still out there,” said Dr Rowe.

“In the mountains of Sulawesi, where we discovered Paucidentomys, healthy forests still nurture rare and remarkable species, however, they are isolated patches imperilled by expanding logging, mining, plantations and other human activities.”

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