X‐ray microtomography and phylogenomics provide insights into the morphology and evolution of an enigmatic Mesozoic insect larva

Abstract

Fossils sometimes show unusual morphological features absent in living organisms, making it difficult to reconstruct both their affinity and their function. We describe here a new lacewing larva, Ankyloleon caudatus gen. et sp.n. (Neuroptera) from the Cretaceous amber of Myanmar, characterized by an abdomen unique among insects, with ‘tail‐like’ terminal segments bearing a ventral pair of vesicles. Phase‐contrast X‐ray microtomography reveals that these structures were dense and equipped with a median duct, suggesting that they were likely pygopods used for locomotion, holding the position through adhesive secretions. Our phylogenetic analyses, combining genomic and morphological data from both living and fossil lacewings, proved critical to placing Ankyloleon gen.n. on the lacewing tree of life as an early representative of the antlion clade, Myrmeleontiformia. These results corroborate the view that derived myrmeleontiform lacewings ‘experimented’ with unusual combinations of features and specializations during their evolutionary history, some of which are now lost. Zoobank registration: urn:lsid:zoobank.org:pub:0C0AC565‐1AC9‐42CC‐831D‐EDA38BA36F64

The Morphological Diversity of Antlion Larvae and Their Closest Relatives over 100 Million Years

“…The impression of a more diverse lacewing fauna in the past is provided by numerous fossils, especially from the Mesozoic (e.g., [46][47][48][49][50][51][52][53][54][55][56]), but also from the Cenozoic era (e.g., [57][58][59][60][61][62]). These fossils include numerous different types of lacewing larvae (e.g., [26,47,50,52,), among them being also larvae that have been interpreted as representatives of the combined group including Myrmeleontidae and Ascalaphidae [47,50,52,57,62,86]. Some of these larvae have more precisely been interpreted as offshoots of the direct evolutionary lineage towards the combined group [50].…”

“…The group traditionally termed Ascalaphidae has in some analyses been resolved as being an ingroup of Myrmeleontidae (i.e., Ascalaphidae being nested within Myrmeleontidae [ 23 ] and renamed Ascalaphinae [ 24 ]). Alternatively, Myrmeleontidae has been resolved as being an ingroup of Ascalaphidae (e.g., [ 25 , 26 ]). The monophyly of a combined group including all representatives traditionally considered Myrmeleontidae and Ascalaphidae seems to not have been challenged.…”

High morphological disparity of neuropteran larvae during the Cretaceous revealed by a new large species

“…The Cretaceous has yielded many unusual-looking neuropteran larvae with morphological characters greatly exceeding the known disparity of the group (e.g. Wang et al 2016;Badano et al 2018Badano et al , 2021Haug et al 2019aHaug et al , b, c, 2020bHerrera-Flórez et al 2020;Hörnig et al 2020, and K. hui also represents such a case. All the evidence indicates that the new larva was a fierce and voracious predator and hunted using a classic example of a lie-in-wait or ambush tactic.…”

“…Furthermore, some Cretaceous lacewing larvae display unique morphological modifications and/or evidence of specialized behaviours that have never been found among living Neuroptera, e.g. predation or kleptoparasitism of web-spinning spiders (Liu et al 2016), liverwort mimesis (Liu et al 2018b) and 'tail-like' terminal segments (Badano et al 2021). Moreover, many fossil lacewing larvae possess a combination of characters different from extant families, making it hard to determine their exact systematic position (Wang et al 2016;Badano et al 2018;Haug et al 2019aHaug et al , b, c, 2020bHerrera-Flórez et al 2020;Hörnig et al 2020;Badano et al 2021).…”

Lepidopteran caterpillars in the Cretaceous: were they a good food source for early birds?

“…In lepidopterans, this differentiation may be easily reco gnised, not least due to the famous children's book "The very hungry caterpillar" (Carle 1969). The larvae, caterpillars, are highly specialised feeding machines (as many other larvae, see discussion in Badano et al 2021) and with this, some of them represent severe pests, destroying enormous amounts of plants. The adults are beautiful entities praised for their importance as pollinators.…”