A group of assassin fly pupae preserved in a single piece of Eocene amber

Abstract

Holometabolous insects represent a mega-diverse group of organisms that are dominant in most terrestrial faunas. All holometabolous insects develop via a specific transitory stage between the last larval stage and the adult, called the pupa. While insects in general have a comparably good fossil record, fossils of pupae of holometabolous insects are relatively rare. We report here four pupal specimens preserved in a single piece of amber. These represent pupa stages of assassin flies, Asilidae, and are most likely representatives of Laphriinae. While dipterans are quite common in the fossil record, especially in amber, representatives of Asilidae are comparably rare. Combining the rarity of the systematic group and the rarity of the specific life stage, these fossil remains of assassin fly pupae are extremely unusual; to date only a single specimen has been depicted in the literature. We discuss the importance of our new finding and possible interpretations regarding behavioural aspects of the group enclosed in amber.