Something is new—under the moon, at least. Researchers have discovered a species of nocturnal ant with a unique taste for mushrooms.

Many ants live symbiotically with fungi. Some even make occasional meals out of the stuff. But the newly found nomadic species, Euprenolepis procera, which roams the rainforests of Malaysia, is the only ant known whose adults rely on mushrooms—the fruiting bodies of fungi—as their primary source of food.

And eat fungi they do, voraciously consuming a smorgasbord of mushroom species, in one observed instance downing an entire 1.4 ounce (40 gram) toadstool in about three hours. They also have been seen making piles of mushroom bits in their dens, chewing the pieces into a kind of fermented paste for both workers and larvae.

Bert Hölldobler, an ant expert at Arizona State University, called the discovery "sensational." "Nothing like that was known before," says Hölldobler, who noted that the mushroom-eating ants are phylogenetically quite distant from their cousins who use fungi for other purposes, such as nest building.

The findings, published in Naturwissenschaften (Life Sciences)  could have important implications for the community of fungi, because ants are remarkably effective and efficient consumers. They also raise the question of the considerable evolutionary changes that would be necessary for E. procera to develop its peculiar diet.

"The ability to specialize completely on that kind of diet is highly unusual. Few animals are able to live exclusively on fungi," says study co-author Volker Witte, a biologist at Ludwig Maximilians University in Munich.

"Once the ability to digest fungal material is developed, it appears as a great niche with low interspecific competition. However, specific lifestyle adaptations are required to reach such a high degree of specialization," adds Witte, who first  discovered the ants as a doctoral student in the late 1990s but did not notice their strange gustatory preferences until 2006.

Witte and a colleague, Ulrich Maschwitz of Johann Wolfgang Goethe University in Frankfurt have been observing E. procera, for the past two years. Witte is set to return with a team to Malaysia next month to conduct more research on the creatures.

The ants could benefit the fungus they eat by dispersing their spores. But the fungus are out of luck if the ants gobble them before the spores mature. "In the latter case," Witte says, "the fungus is kind of castrated."