Cretaceous chimera – an unusual 100-million-year old neuropteran larva from the “experimental phase” of insect evolution

Abstract

Neuropteran insects possess very distinct larval stages with prominent paired piercing sucking stylets and a specialised sclerite, the neck, between the head and the first thoracic segment. Some larva of Crocinae (Nemopteridae) are further specialised by possessing a very elongated neck region. The fossil record has already provided a large variety of neuropteran larvae, yet so far a truly long-necked form was missing. Here we report such a fossil larva, with an elongated neck region from 100-million-year old Burmese amber. The specimen possesses a unique combination of characters unknown in any modern or fossil neuropteran larva. Besides the elongated neck it possesses three distinct teeth in the stylets, a character mostly known in larval forms of owl flies (Ascalaphidae) and ant lions (Myrmeleontidae), and a slender trunk as known in aphid lions (larvae of the groups Chrysopidae and Hemerobiidae). We must therefore conclude that the fossil species must have evolved certain characters in convergence to other lineages of Neuroptera resulting in a chimera-like morphology. We discuss possible interpretations of character evolution of larvae within Neuroptera.