FOSSIL SNAKEFLY PUPAE FROM ABOUT 100 MILLION YEARS OLD AMBER REVEAL AN UNUSUAL MORPHOLOGY OF THE ANTENNAE

A key aspect of the holometabolan evolutionary success is their metamorphosis. It allows larvae and adults to exploit quite different resources and reduce competition between the two. The often strongly differing morphology of larvae and adults is mediated by the specific intermediate stage, the pupa. Fossil pupae provide valuable information for the reconstruction of the evolutionary history of this so important developmental stage. However, pupae are relatively rarely found in the fossil record, and they seem even less often depicted in the literature. Here, we report two new fossil pupae preserved in about 100 million years old Kachin amber, Myanmar. These represent the first fossil pupae of the group of snakeflies, Raphidioptera. The two specimens resemble modern snakefly pupae in overall morphology and especially in the morphology of the ovipositor. However, they also differ in certain aspects, indicating differences in developmental timing. One specimen is particularly notable for its long, curled antennae. Extant snakeflies have rather short antennae in all life stages. Yet, in the Cretaceous few species have long antennae as adults, and also some larvae are known with rather long antennae. The other pupa has shorter antennae and is preserved in the same amber specimen as another snakefly, a larva with rather long antennae. The new snakefly pupa with its extraordinarily long antennae underpins the exceptional evolutionary radiations in the Cretaceous.