Possible long-proboscid insect pollinators from the Early Permian of Russia

Insect pollination is one of the hallmarks of flowering plants.1 Bees, moths, flies, and some other pollinators evolved elongate siphonate mouthparts for sucking concealed nectar and occasionally other liquids.2 How-ever, it is clear from the fossil record that insects with similar adaptations appeared long before the mid -Cretaceous radiation of angiosperms. These insects most probably used their proboscis to reach pollination drops and other sugary fluids that were hidden in the cones of extinct gymnosperms, pollinating them in the process.3-6 The vast majority of these gymnosperm-associated long-proboscid insects have been reported from the Middle Jurassic to the Early Cretaceous, i.e., the time interval that immediately predated the advent of flowering plants.7 By contrast, the Paleozoic stage of the co-evolution between long-proboscid insect pol-linators and plants has remained poorly understood. Here, we report a putative pollination mutualism involving long-proboscid holometabolous insects (Panorpida: Protomeropidae) from the Early Permian of Russia (ca. 283-273 Ma). Their elongate mouthparts have very similar morphology to those of some present-day nectarivorous Coleoptera and Hymenoptera and probably served to imbibe micropylar secretions from the semi-closed ovulate organs of the gymnosperms of a peltaspermalean affinity that have been found in the same locality. This is the earliest record of insects with siphonate-like mouthparts, which could indicate that the complex interactions between pollinators and gymnosperms predate the first flowering plants by over 100 Ma.

Automated summary

Insect pollination is a characteristic of flowering plants. Fossil records show that insects with elongate siphonate mouthparts, similar to those seen in present-day nectarivorous beetles and hymenopterans, existed long before the flowering plants. These insects most likely used their proboscis to obtain pollination drops and sugary fluids from cones of extinct gymnosperms. A recent discovery in Russia of long-proboscid holometabolous insects from the Early Permian provides evidence of a pollination mutualism with gymnosperms, suggesting that the complex interactions between pollinators and gymnosperms predates the first flowering plants by over 100 million years.