Abstract
Simple SummaryAmong insects, the group Neuroptera (lacewings) appears to be less well known to most people, at least in comparison to beetles, butterflies, or wasps. Nowadays, about 6000 species of lacewings are known, but the fossil record yields a large number of further representatives, hinting to a possibly larger role lacewings played in ecosystems of the past. Especially the larvae of lacewings (most prominent examples are antlions) exhibit a large morphological diversity, with fossils exhibiting many peculiar morphologies not known from the modern fauna. Lacewing larvae are well recognisable as such by their prominent jaws, also called stylets. In this study, we analysed the change of larval diversity in different lacewing groups based on the shape of these stylets together with the heads. Our results point to a complex pattern of diversity changes in Neuroptera from 100 million years ago until today.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.
Highlights
Lacewings seem to be lesser-known representatives of the group Insecta, at least in comparison with butterflies, beetles, or wasps
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 considered all available depictions of larvae of the groups Dilaridae, Berothidae, Rhachiberothidae, Mantispidae, and Osmylidae
Summary
Lacewings seem to be lesser-known representatives of the group Insecta, at least in comparison with butterflies, beetles, or wasps. As in many piercing-sucking mouthparts, those of lacewing larvae face a significant mechanical challenge: to penetrate the surface of a prey item it is necessary to produce a counteracting force, otherwise the predator pushes itself back when attempting to pierce the prey, or just pushes the prey away from itself. The solution for this challenge in most lacewing larvae is simple: counteracting mouthparts. When such stylets snap together with the prey between them, the force produced by one stylet counteracts that of the other one, leaving no resulting force pushing back the predator, instead transmitting this force onto the prey surface, penetrating it
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