Amber fossil suggests ancient beetle pollinated evergreen cycads

Aug. 16 (UPI) -- A newly analyzed amber fossil has offered the earliest evidence of a plant-pollinator relationship between cycads and insects.

Pollinators bring to mind flowering plants. Modern pollinators, bees and butterflies, are seen flying from flower to flower. But before angiosperms emerged, a group of evergreen gymnosperms called cycads dominated the landscape.

Those cycads didn't boast flowers, they did have pollen. And as the newly described amber fossil revealed, ancient boganiid beetles helped transport that pollen.

"Boganiid beetles have been ancient pollinators for cycads since the age of cycads and dinosaurs," Chenyang Cai, research fellow at the University of Bristol, said in a news release. "Our find indicates a probable ancient origin of beetle pollination of cycads at least in the Early Jurassic, long before angiosperm dominance and the radiation of flowering-plant pollinators, such as bees, later in the Cretaceous."

Cai first encountered the amber fossil while conducting research at the Chinese Academy of Sciences' Nanjing Institute of Geology and Palaeontology. To Cai, the beetle's large mandibles with bristly cavities looked like they were designed specifically to carry cycad pollen.

Cai cut and polished the piece of amber to get a clearer view of the beetle inside. Under the microscope, he spotted tiny pollen grains. Liqin Li, an ancient pollen expert at the Chinese Academy of Sciences, confirmed the pollen grains belonged to an ancient cycad species.

Cycads are still present today. They are often mistaken for palms or ferns. Millions of years ago, cycads were much more abundant and diverse.

The latest research -- published this week in the journal Current Biology -- suggests boganiid beetles played an important role in enabling cycad diversification.

As phylogenetic analysis by Cai and his colleagues revealed, cycad pollination ran in the family. One of the beetle's close relatives, Australian paracucujus, pollinated an ancient Australian cycad species, Macrozamia riedlei.

The amber fossils suggests the cycad-beetle relationship has deep roots in evolutionary history. Scientists believe other ancient cycad pollinators are out there waiting to be discovered.