The missing wings on an ‘alien’ beetle pose an evolutionary mystery

The insect in the small specimen collection at Lund University in Sweden looked out of place.

“OK, this is a joke” Vinicio Ferreira, insect taxonomist and evolutionary biologist, he told himself. “It’s a joke.”

The beetle — just a tenth of an inch thick and found in 1991 in Oaxaca, Mexico, among the leaf litter of a pine and oak forest at an elevation of more than 9,500 feet by naturalist Richard Baranowski — was definitely male. But one of the animal’s defining characteristics was missing: the hard anterior shell known to scientists as the elytra.

After careful analysis, Dr. Ferreira described the insect this month in the Zoological Journal of the Linnean Society as a previously unknown but “extraordinary” species of elytraless beetle: Xenomorphon baranowskii.

“Boom. We found this really weird animal. The ‘alien’ beetle,” said Dr. Ferreira, choosing a name that honored Dr. Baranwoski and also brought to mind the “Alien” from his sci-fi film franchise favorite.

“Finally we found one. I think it’s very exciting,” she said Michael Ivi, curator of entomology at Montana State University who was not involved in the research. “This is an incredible beast.”

“We can’t do much yet, but until this discovery we didn’t know there was anything to look for,” he added.

Wings consume a lot of energy, so over the course of evolutionary history, many insect species have independently lost the ability to fly. But there are more than half a million known beetle species, and until now all have had at least some form of hard anterior elytra. Even in cases where it is not used for flight and is fused together, this shell-like wing cover is thought to be one of the keys to the beetle’s survival. It protects their soft body and gets them into small crevices and out of dangerous situations.

In the case of Dr. Ferreira’s alien beetle, he and his colleagues speculate that stopping flying and losing its elytra could be a protective measure to avoid being blown away by large gusts of wind at the high altitudes where they inhabit.

Dr. Ferreira has also linked the species to a little-known evolutionary trend he and others studied called paedomorphosis. In this phenomenon, adult females of some beetle species retain some of their juvenile characteristics, look more like larvae, and sometimes even lose their wings. The winglessness of male Xenomorphon baranowskii resembles what has been found in females of those beetle species.

But typically, male beetles use their power of flight to chase females far and wide to mate. So if paedomorphosis was already perplexing in female beetles, it makes even less sense that a male beetle would not develop wings as an adult. “It’s the most extremist example of paedomorphosis,” said Dr. Ferreira.

“It’s not so great for you to be a paedomorph,” he added, as it leaves individual beetles more vulnerable to threats and unable to get very far. But, her team speculates, losing its front wings and the ability to move could allow a beetle species to become more specialized and more successful in occupying a tiny geographic niche.

These findings could serve as an example of how extremely adaptable beetles have been throughout their evolution, a trait that makes them one of the most successful animals on the planet. “This is an extreme situation,” he said Robert Anderson, a Canadian Museum of Nature researcher who was not involved in this study. “This is obviously very out there in terms of weirdness.”

The description is also based on a single Xenomorphon specimen, and while entire insect species are often described from one-off discoveries, researchers know virtually nothing else about the animal. Its DNA cannot be studied, there is no data on its life history, and there is no record of what females of this species might be like. The next step would be to go up that Mexican mountain in hopes of finding more elytra-less beetles.

“I honestly knew it was going to happen one day,” said Dr. Ferreira. “It’s really baffling, but anything is possible with beetles.”