A McMaster University biologist has found an odd new species — a nearly toothless rat — in a remote Indonesian rainforest.

Jacob Esselstyn was doing research on the island of Sulawesi when he came across what is now known as the toothless shrew rat. The rat has no molars, just some sparse incisors.

“It's not that uncommon to find a new species, but it's uncommon to find something that strange,” said Esselstyn, a post-doctoral fellow at McMaster.

The rat's diet consists mainly of earthworms, which means it likely evolved over millions of years to have no teeth, Esselstyn said.

Jake Esselstyn does research on the island of Sulawesi.

He was on Sulawesi, known for its diverse ecology, with fellow researchers Anang Achmadi and Kevin Rowe when he found the unusual rat in one of their bucket traps.

Esselstyn's excitement caused him to holler so loudly that Achmadi ran up the hill, thinking he'd fallen and hurt himself.

“We said a lot of words you can't quote,” he said.

The specimen was dead, so Esselstyn photographed it, preserved it and deposited it at a museum for others to study. They have only seen one other, and have never seen a live one.

Esselstyn is now working on getting DNA from other species on the island to find the rat's nearest relative. That will give him a sense of how quickly the rat evolved.

The team's findings were published in a recent issue of the journal Biology Letters. The rat's scientific name is paucidentomys vermidax, which means “few toothed mouse, devourer of worms.”

The world is in the midst of a “massive extinction crisis,” Esselstyn said, which makes new species discoveries all the more important.

“We're losing biodiversity left and right, and we don't even know what we're losing if we haven't documented it,” he said. “The more we know about what's out there, the more we can know where to focus conservation efforts.”