Neuroptera (lacewings) is today a rather small lineage of Holometabola. These representatives of Insecta have mostly predatory larvae with prominent venom-injecting stylets formed by upper and lower jaws. These impressive larvae can be found not only in the modern fauna, but sometimes also as fossils, predominantly preserved in amber. Here we report a new specimen of a lacewing larva from Miocene Mexican amber, most likely a larva of an owlfly (Ascalaphidae) with large prominent stylets, each with three teeth. These stylets arise from a more or less square-shaped head (in dorsal view) that has distinct eye hills with at least three simple eyes (stemmata) each. The trunk is rather short. Trunk segments possess finger-like protrusions carrying numerous setae, which could have been used to attach camouflaging debris to it. Remarkably, the specimen represents only the second report of a lacewing from Miocene Mexican amber, and the first larva. Additionally, we review the Miocene record of lacewing larvae. It includes otherwise only fossils preserved in Dominican amber and remains rather scarce, with only eight specimens in the literature so far. While there seem to be additional specimens in private collections, the overall number is astonishingly low compared to the numbers in Eocene and Cretaceous ambers. Ecological and taphonomic factors possibly explaining the rarity of lacewing larvae in Miocene amber are discussed here.
When a vertebrate carcass begins its decay in terrestrial environments, a succession of different necrophagous arthropod species, mainly insects, are attracted. Trophic aspects of the Mesozoic environments are of great comparative interest, to understand similarities and differences with extant counterparts. Here, we comprehensively study several exceptional Cretaceous amber pieces, in order to determine the early necrophagy by insects (flies in our case) on lizard specimens, ca. 99 Ma old. To obtain well-supported palaeoecological data from our amber assemblages, special attention has been paid in the analysis of the taphonomy, succession (stratigraphy), and content of the different amber layers, originally resin flows. In this respect, we revisited the concept of syninclusion, establishing two categories to make the palaeoecological inferences more accurate: eusyninclusions and parasyninclusions. We observe that resin acted as a “necrophagous trap”. The lack of dipteran larvae and the presence of phorid flies indicates decay was in an early stage when the process was recorded. Similar patterns to those in our Cretaceous cases have been observed in Miocene ambers and actualistic experiments using sticky traps, which also act as “necrophagous traps”; for example, we observed that flies were indicative of the early necrophagous stage, but also ants. In contrast, the absence of ants in our Late Cretaceous cases confirms the rareness of ants during the Cretaceous and suggests that early ants lacked this trophic strategy, possibly related to their sociability and recruitment foraging strategies, which developed later in the dimensions we know them today. This situation potentially made necrophagy by insects less efficient in the Mesozoic.
Hybotidae fly species, also known as dance flies, in Cretaceous ambers have been described from Lebanon, France, Myanmar, Russia, and Canada. Here we describe Grimaldipeza coelica gen. et sp. n., and recognize another two un-named species, in Spanish amber from the middle Albian El Soplao and lower Cenomanian La Hoya outcrops. The fore tibial gland is present in the new genus, which is characteristic of the family Hybotidae. We compare Grimaldipeza coelica gen. et sp. n. with the holotypes of Trichinites cretaceus Hennig, 1970 and Ecommocydromia difficilis Schlüter, 1978, and clarify some morphological details present in the latter two species. Further taxonomic placement beyond family of the here described new genus was not possible and remains incertae sedis within Hybotidae until extant subfamilies are better defined. We provide new paleoecological data of the hybotids, together with paleogeographical and life paleoenvironmental notes. A table with the known Cretaceous Hybotidae is provided. Furthermore, the La Hoya amber-bearing outcrop is described in detail, filling the information gap for this deposit.
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