Changes in the Morphological Diversity of Larvae of Lance Lacewings, Mantis Lacewings and Their Closer Relatives over 100 Million Years.

Neuroptera, the group of lacewings, comprises only about 6000 species in the modern fauna, but is generally assumed to have been more diverse and important in the past. A major factor of the modern-day ecological diversity of the group, and supposedly in the past as well, is represented by the highly specialised larval forms of lacewings. Quantitative analyses of the morphology of larvae revealed a loss of morphological diversity in several lineages. Here we explored the diversity of the larvae of mantis lacewings (Mantispidae), lance lacewings (Osmylidae), beaded lacewings (Berothidae and Rhachiberothidae, the latter potentially an ingroup of Berothidae), and pleasing lacewings (Dilaridae), as well as fossil larvae, preserved in amber, resembling these. We used shape analysis of the head capsule and stylets (pair of conjoined jaws) as a basis due to the high availability of this body region in extant and fossil specimens and the ecological importance of this region. The analysis revealed a rather constant morphological diversity in Berothidae. Mantispidae appears to have lost certain forms of larvae, but has seen a drastic increase of larval diversity after the Cretaceous; this is in contrast to a significant decrease in diversity in adult forms.