‘Mammoth Weevil’ Found Preserved in Mid-Cretaceous Amber

A fossilized long-bodied weevil found in mid-Cretaceous amber from northern Myanmar represents a new tribe, genus and species and dates back some 100 million years.

Rhamphophorus legalovii. Image credit: Poinar & Brown, doi: 10.1016/j.cretres.2021.104948.

Rhamphophorus legalovii. Image credit: Poinar & Brown, doi: 10.1016/j.cretres.2021.104948.

Weevils are plant-eating beetles known for their elongated snouts. They are usually small, less than 6 mm in length, and herbivorous.

Over 97,000 species of weevils are currently recognized. Well-known North American species are the boll weevil that attacks cotton, the alfalfa weevil and the strawberry root weevil.

Weevils with straight antennae are categorized as primitive weevils, and those whose antennae feature an elbow-like bend are known as true weevils.

The new species, named Rhamphophorus legalovii, is a primitive weevil with an 11-segment antenna.

“We call the male specimen a ‘mammoth weevil’ because of its ‘monstrous trunk’ — also known as the weevil’s rostrum or beak,” said Professor George Poinar Jr., a researcher in the Department of Integrative Biology at Oregon State University.

Rhamphophorus legalovii probably wielded its trunk as a weapon while in combat with other males over females.”

Rhamphophorus legalovii was is 5.5 mm long, almost half of which is head and rostrum. It likely lived on the ground rather than in trees.

“It had extended middle foot segments that might have increased its ability to grasp plant surfaces or better reach its foes during fights for females. It would be interesting to know if females also had this feature,” Professor Poinar said.

Rhamphophorus legalovii belongs to the sub-family Cimberidinae, consisting of particularly long-nosed weevils whose physical characteristics are developed like highly specialized tools.

Of the 70 known species of Cimberidinae, many are sexually dimorphic — males and females look quite different from one another. Thus the female of Rhamphophorus legalovii probably had a much shorter rostrum.

Professor Poinar and his colleague, Alex Brown, placed the new species in the newly-established tribe Rhamphophorini in the family Nemonychidae, whose members are known as pine flower weevils.

“The story of the family’s ancient history is told by species in Mesozoic amber deposits, although no extinct or extant species with such elongated rostrums are known,”

“The larvae and adults of many nemonychids eat pollen from developing male cones of pines and other conifers.”

A paper on the findings was published in the journal Cretaceous Research.

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George Poinar Jr. & Alex E. Brown. 2021. A new tribe, genus and species of weevil, Rhamphophorus legalovii gen. et sp. nov., (Coleoptera, Nemonychidae, Rhamphophorini tribe nov.) in mid-Cretaceous Burmese amber. Cretaceous Research 127: 104948; doi: 10.1016/j.cretres.2021.104948

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