A fossil trapped in Myanmar amber reveals the mysterious origins of glowing insects

A strange worm fossil found trapped in amber in Myanmar is shedding new light on the origin of the glowing insects, scientists say.

Various fish, mushrooms and deep-sea insects are capable of emitting light in a phenomenon called bioluminescence. In the world today, most bioluminescent organisms belong to the order Coleoptera, particularly the larger family Elateroidea, which includes fireflies, click beetles and their relatives.

Most insects of this species have soft bodies, but it is difficult to find fossils and trace the origin of bioluminescence.

Therefore, the early evolution of bioluminescence in fireflies is largely unknown, say researchers from the Chinese Academy of Sciences.

Fossil fireflies are particularly rare, with a solitary example dated earlier to the Mesozoic era of dinosaurs 252 to 66 million years ago.

Burmese amber containing the fossil firefly from about 145 to 65 million years ago, which represents a transitional stage in the evolution of its species, was only found in 2021.

Researchers from the Chinese Academy of Sciences say the fossil insect represents a new genus and species called Flammarionella hehaikuni.

A distinctive feature is the oval-shaped sensory receptors. Researchers say the ancient worm probably also had special organs for detecting smell.

The light-emitting organ near the tip of its abdomen closely resembled that of the modern earthworm.

“The light organ near the abdominal apex of Flammarionella resembles that found in light-producing fireflies,” the researchers say.

This contrasts with the light organs of other species of beetles belonging to the cretophengoda group.

The study confirms that the characteristics that allowed fireflies to grow have remained evolutionarily stable. “The growing fossil record of lampyrids provides direct evidence that the impressive light displays of fireflies were already established by the late Mesozoic,” say the scientists.

The findings also show that even during the time of the dinosaurs there were several types of light organs among insects.

The researchers hope that future fossil discoveries may shed further light on the evolution and mechanisms behind the origin of insect bioluminescence.