New extreme morphologies as exemplified by 100 million-year-old lacewing larvae

Abstract

Larvae of the group Holometabola (beetles, wasps, flies, moths and others) differ significantly in their morphology from their corresponding adults. In most larvae, appendages and other structures protruding from the body (antennae, palps, legs, trunk processes) appear less elongate than in their corresponding adults, providing the impression that these larvae are restricted to a certain degree in developing more elongate structures. We provide here numerous counterexamples of larvae of lacewings (Neuroptera). These include different forms of elongated antennae, mandibles, maxillae, labial palps, legs, trunk processes and neck regions. Most of these examples are larvae preserved in different types of 100 million-year-old amber. The longest neck region was found in an extant specimen. All these examples demonstrate that certain branches of Neuroptera indeed had larval forms that possessed strongly elongated structures. Hence there is no principal constraint that hinders holometabolan larvae to develop such structures.