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Cretaceous Bug With Weirdly Exaggerated Antennae Discovered In 99-Million-Year-Old Amber

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Katy Evans

Managing Editor

clockFeb 28 2020, 15:49 UTC

The strange new species of leaf-footed bug has antennae nearly twice as long as its body. Bao-Jie Du et al., 2020

Researchers in China have discovered a strange type of Cretaceous bug with exaggerated antennae stuck in 99-million-year-old amber. In fact, it’s so weird, it’s been declared a brand new species.

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For a bug just hanging out on a tree in the Cretaceous period, getting swallowed up by yellow tree goop spelling your inevitable doom doesn’t sound like a good thing at the time, but 100 million years later, it can make the difference between disappearing into the annals of history or fame and glory.

This insect, incredibly preserved in a block of amber found in Myanmar in 2018, is a member of the large and common Coreidae family of insects, known as leaf-footed bugs. However, it’s the first-ever report of a leaf-footed bug in amber, and only the second member of the Coreoidea superfamily to be preserved like this.

Though it has similar characteristics to another Coreidae genus Chariesterus, the researchers describe it as “markedly different from all previously described fossil Coreidae in the scale of the antennal exaggeration,” in their paper available to view on the pre-print server bioRxiv.

"We were surprised when we first examined the specimen. We have never seen such a peculiar antenna, whether in extant species, fossils or ambers," author Da-Wei Huang told IFLScience. "It was confirmed as a new species after a review of the relevant literature in order to ensure accuracy."

Close-up of the antennae. The scale bar is 1mm. Bao-Jie Du et al., 2020

Magnusantenna wuae, literally meaning “large antenna”, has the biggest and fanciest antennae of any other known species of Coreidae, and although they make the bug stand out, they may have also been its downfall.

"With the development of angiosperms [flowering plants], sufficient food resources provide the possibility for the nymph to develop such large antennae," Huang said. "Since the Cretaceous, the prosperity of angiosperms has promoted the rise of herbivorous and carnivorous insects, birds and so on, which limited the survival resources of the nymph and increased the number of predators. In addition, the large appendages probably made it move slowly, which would have been a disadvantage when fleeing a predator."

Its extreme antennae are 12 times the size of its head, about as long as its total body length, with four segments ending in huge (for this bug, at least) petal-shaped flaps. The specimen trapped in this amber tomb is a juvenile insect, known as a nymph, but the researchers hypothesize that these enlarged antennae would carry on into adulthood and be used as displays in mating behavior.

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"The large and delicate antenna can promote long-distance chemical communication, reduce the risk of predation, and even may play a role in sexual display, thereby enhancing the adaptability to the environment," Huang said.

The development of prominent antennae as a characteristic is little known in ancient insect species as not many are encased in amber for our perusal. But, expanded antennae have evolved many times in different insect groups, usually in males, and are a common characteristic of displaying sexual fitness – much like impressive antlers of stags. 

Reconstruction of what Magnusantenna wuae would have looked like. Bao-Jie Du et al., 2020

Interestingly, the researchers also suggest the expansive feelers may have had a large number of olfactory receptors that would have made M. wuae particularly good at locating females over long distances. This, you would think, would make them prime candidates for survival, but the researchers point out the large appendages may have made them more visible to predators too.

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The obvious argument against the antenna being used for sexual display is that they appear to be fully formed in the juvenile already. However, the researches are also hedging their bets that the unusual appendages could have been used as a defense against predators too.

Camouflage is common in insects – whether it’s mimicking bark, fading into foliage or looking like something else entirely. Misdirection is a more unusual defense mechanism, but it is still found in the animal kingdom, when a particular part of a creature’s body is designed to attract the attention of a predator, so as to protect the more vital parts. The researchers suggest these leaf-like flaps may have been used just for that, and that is why they are so far away from the bug’s body.

Their shape and lack of bright pigment could also mean it was a leaf-mimic, using its petal or leaf-shaped flaps to disguise itself as part of the scenery. Without more examples, we may never know why this tiny bug developed such a far-out set of feelers. 


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