Long-headed predators in Cretaceous amber—fossil findings of an unusual type of lacewing larva

Abstract

Lacewing larvae (Neuroptera) are known to be fierce predators which are morphologically highly specialised for a raptorial lifestyle. Mandibular-maxillary stylets are characteristic for all larvae of this group; these stylets can be extraordinarily massive. Despite these distinct sucking-piercing stylets, also other extreme features occur in some ingroups, such as an extremely elongated neck. In larvae of thread-winged lacewings (Crocinae) the neck can reach up to about one third of the body length; they are also called ‘long-necked antlions’. Even though the larvae of living neuropteran species show a variety of conspicuous morphologies today, indeed 100 million years ago, in the Cretaceous, Neuroptera seems to have had an even more “experimental phase”. Several larval specimens are known so far especially in Myanmar, Spanish and Lebanese amber from the Cretaceous with unique and unusual character combinations not found in any group living today. We describe here ten new fossil findings of one of these types of larvae with elongated head capsule in Myanmar amber, previously only known from a single specimen. We compared the head shapes of the new specimens with those of 190 specimens of other lacewing larvae and discuss further implications of our findings, especially making functional comparisons with long-necked antlions.

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 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 ]), 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...…”

The first fossil false click beetle larva preserved in amber

“…In contrast to that, the already known fossil larva of Eucnemidae strongly resembles modern-day larvae (Chang et al 2016). Therefore, the group Eucnemidae emphasizes again how the large diversity of larvae in the Cretaceous fauna is structured: already very modern appearing morphologies (Chang et al 2016;Wang et al 2016;Haug et al 2018) cooccur with now extinct morphologies (Badano et al 2018;Haug et al 2020a, b;Zippel et al 2021); the latter ones include also animals with distinct mixes of features. Such "chimera"-type morphologies are likely "experimental" morphologies of an early phase of diversification of a lineage (Haug et al 2019a, b;Baranov et al 2020).…”

An Expanded View on the Morphological Diversity of Long-Nosed Antlion Larvae Further Supports a Decline of Silky Lacewings in the Past 100 Million Years

“…Quantitative morphology offers a framework for overcoming both problems, facilitating a comparison of larval forms throughout the fossil history of a group. Such a comparative frame has been used for various lineages of lacewings [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”