The two-inch-long (five-centimeter-long) black insects are shrouded in mystery—all of the wasp specimens caught so far have been dead.
"I'm not certain any researcher has ever seen one alive, but they are very bizarre-looking," said study co-author Lynn Kimsey, an entomologist at the University of California, Davis, who co-discovered the insect.
"It's the extreme version of the [larrine wasp] subfamily they belong to."
Larrine wasps typically dig nests for their eggs and larvae in open, sandy areas. The adults grow no longer than an inch (2.5 centimeters)—making the newly discovered Megalara garuda the "king of wasps," according to the study authors.
Wasp Males' Spiky Jaws
Female M. garuda wasps look like most other wasp species, but the males grow long, sickle-shaped jaws.
The males' flattened faces and large, spiked jaws may be clever adaptations to protect a nest that contains vulnerable larvae, she suggested.
"Other wasps of the same species often rob burrows for food, and parasites try to get in there, too," she said. "There's a serious advantage to having the nest guarded. This may be how the male helps guarantee his paternity."
In general, "we don't know what this wasp does," Kimsey said. "But it probably feeds its larvae grasshoppers or katydids, like other wasps in its subfamily."
"Mythical" Wasp Under Threat
Kimsey and co-author Michael Ohl, of Berlin's Humboldt University, caught their first glimpse of the new wasp in Indonesia's Museum Zoologicum Bogoriense, where the bugs had been kept in storage since 1930. Ohl also found unidentified specimens at the Humboldt Museum in Berlin.
On a 2009 expedition, the team found more wasps at a cacao plantation in the southeastern mountains of Sulawesi. In naming M. garuda, the team looked to the national symbol of Indonesia: a mythical half-human, half-bird creature in the Hindu religion called Garuda.
Although as many as a hundred thousand species of insects may live on Sulawesi, Kimsey suspects "only half have names."
But the fates of these species—including the newfound wasp—are in jeopardy. Since the 1960s forests in the region have been increasingly leveled to plant several types of crops. (Read about rain forest threats.)
"The place where we collected wasps is slated to be an open-pit nickel mine," Kimsey said.
"Just thinking about it makes me sick to my stomach."
The new giant-wasp study recently appeared in the journal ZooKeys.