An insect locked in Cretaceous-era amber has bizarrely wide and long antennae that may have been used to confuse predators or help disguise these insects as they foraged on branches.
“This may be a new type for insect antennae,” says Bao-Jie Du at Nankai University in China. She says she got a shock when she first examined the 99-million-year-old specimen in 2018. Amber collected in northern Myanmar contains a beautifully preserved juvenile Magnusantenna wuae, an insect from the Coreidae family, also known as leaf-footed bugs or squash bugs (pictured above).
This nymph’s antennae are more exaggerated than those of all other species in the Coreidae family. Du had never seen anything quite like it.
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The far-out feelers are about as long as the insect’s body and adorned with flap-like structures that fan out to more than four times wider than the bug’s head. The antennal flaps look a little like large fish scales or young leaves.
The big question is why they evolved. Du and her colleagues suggest that they might have been used for displays during mating behaviour or perhaps as false targets so that a predator would miss the true body of the insect in an attack. They also argue that the antennae would have been extra sensitive, given their large surface area.
“It’s lovely,” says Max Barclay at the Natural History Museum in London. “It’s an extreme version of something we’re familiar with.” However, he says a sexual function is unlikely since the antennae already seem to be well-developed in the juvenile insect.
“I think it’s a leaf-mimic,” he says. With no sign of bright pigment on the antennae, Barclay suggests they may have allowed the insect to disguise itself as a twig with tiny leaves while it sucked the sap out of a branch. Predators would presumably miss it and move on.
Du argues that such spectacular antennae might have incurred a cost, slowing the insect’s movement or even making it more conspicuous to predators. She says that could have doomed the survival of the bug, and may be why we don’t see such extreme appendages on this insect’s modern descendants.
But Barclay disagrees. Large features on an animal can sometimes prove problematic when their environment changes – for example, the Irish elk’s gigantic antlers are thought to have become a hindrance when the climate warmed around 8000 years ago, causing dense forests to grow.
In the case of this Cretaceous insect, though, no such stumbling block is obvious. “I don’t believe that evolution produces, over thousands of generations, structures that are harmful,” says Barclay.
Reference: bioRxiv, DOI:
