Search

Summary A hallmark of animals that are eusocial, or those with advanced sociality, is reproductive specialization into worker and queen castes [ 1–3 ]. In the most derived societies, these divisions are essentially fixed and in some arthropods, include further specialization—a tripartite system with a soldier caste that defends the colony [ 1 ]. Eusociality has originated numerous times among insects but is believed to have appeared first in the termites (Isoptera), in the Early Cretaceous [ 4 ]. However, all termites known from the Cretaceous have, until now, only been winged reproductives (alates and dealates); the earliest soldiers and definitive workers were known from just the Miocene (ca. 17–20 million years ago [mya]) [ 4 ]. Here, we report six termite species preserved in Early Cretaceous (ca. 100 mya) amber from Myanmar, one described as Krishnatermes yoddha gen. et sp. nov., comprising the worker/pseudergate, winged reproductive, and soldier, and a second species, Gigantotermes rex gen. et sp. nov., based on one of the largest soldier termites yet known. Phylogenetic analysis indicates that Krishnatermes are in the basal “ Meiatermes -grade” of Cretaceous termites. Workers/pseudergates of another four species are briefly described, but not named. One of these workers/pseudergates reveals that ants—the most serious enemies of modern termites—lived in close proximity to termites in the Burmese paleofauna. These discoveries demonstrate the Mesozoic antiquity of specialized termite caste systems and corroborate that among all social species, termites probably had the original societies. [ABSTRACT FROM AUTHOR]

Summary It goes without saying that insects epitomize diversity, and with over a million documented species they stand out as one of the most remarkable lineages in the 3.5-billion-year history of life on earth ( Figure 1 ). This reality is passé to even the layperson and is taken for granted in the same way none of us think much of our breathing as we go about our day, and yet insects are just as vital to our existence. Insects are simultaneously familiar and foreign to us, and while a small fraction are beloved or reviled, most are simply ignored. These inexorable evolutionary overachievers outnumber us all, their segmented body plan is remarkably labile, they combine a capacity for high rates of speciation with low levels of natural extinction, and their history of successes eclipses those of the more familiar ages of dinosaurs and mammals alike. It is their evolution — persisting over vast expanses of geological time and inextricably implicated in the diversification of other lineages — that stands as one of the most expansive subjects in biology. [ABSTRACT FROM AUTHOR]

Although scales are a defining and conspicuous feature of moths and butterflies (Lepidoptera), 1–3 their earliest evolution predates the group but is shrouded by a dearth of fossil evidence. Herein, we report two new species in mid-Cretaceous Kachin amber, representing lineages closely related to Lepidoptera: one represents the extinct Tarachoptera, with dense scales on the fore- and hindwings, while the other is an early lineage of caddisflies, with a hindwing covered by a single layer of angustifoliate scales. A novel phylogenetic analysis of 174 morphological characters and 73 extant and fossil representatives of Mecopterida demonstrates a monophyletic origin of scales in the common ancestor of Tarachoptera, Trichoptera, and Lepidoptera; that Tarachoptera are monophyletic but their scale morphology is plesiomorphic for the whole group; and that scales were lost early in caddisfly evolution before reappearing multiple times within the clade. Collectively, these fossils provide clarity into the origin and early evolution of scales before their diversification among the moths and butterflies. • Lepidochlamidae fam. nov is the most basal lineage of Trichoptera with scales • Support the Tarachoptera as a monophyletic group at the base of Amphiesmenoptera • Scales are a monophyletic origin in the common ancestors of Endymenoptera • Scales lost in Eutrichoptera, but evolved and further developed in moths and butterflies Lepidochlamidae of Trichoptera and Tarachoptera in the mid-Cretaceous (99 Ma) have small and angustifoliate scales. Based on phylogenetic and morphometric analyses, Wang et al. suggest that scales are the ancestral state in Endymenoptera, followed by a major loss in Eutrichoptera and developed in moths and butterflies respectively. [ABSTRACT FROM AUTHOR]

Summary Iconic examples of insect pollination have emphasized narrowly specialized pollinator mutualisms such as figs and fig wasps [ 1 ] and yuccas and yucca moths [ 2 ]. However, recent attention by pollination ecologists has focused on the broad spectra of pollinated plants by generalist pollinators such as bees. Bees have great impact for formulating hypotheses regarding specialization versus generalization in pollination mutualisms [ 3, 4 ]. We report the pollination biology of six northern European species of an extinct tribe of pollen-basket-bearing apine bees, Electrapini, of early–middle Eocene age, examined from two deposits of 48 and 44 million years in age [ 5 ]. These bees exhibit a pattern of generalized, incidental pollen occurring randomly on their heads, thoraces, and abdomens, obtained from diverse, nectar-bearing plants. By contrast, a more restricted suite of pollen was acquired for metatibial pollen baskets (corbiculae) of the same bee taxa from a taxonomically much narrower suite of arborescent, evergreen hosts with uniform flower structure. The stereotyped plant sources of the specialist strategy of pollen collection consisted of pentamerous, radially symmetrical flowers with a conspicuous gynoecium surrounded by prominent nectar reward, organized in structurally similar compound inflorescences. Pollen specialization in bees occurs not for efficient pollination but rather in the corbiculate Electrapini as food for bee larvae (brood) and involves packing corbiculae with moistened pollen that rapidly loses viability with age. This specialist strategy was a well-developed preference by the early Eocene, providing a geochronologic midpoint assessment of bee pollen-collection strategies. [ABSTRACT FROM AUTHOR]

Paleogene arthropod biotas have proved important for tracing the faunal turnover and intercontinental faunal interchange driven by climatic warming and geodynamic events [1-5]. Despite the large number of Paleogene fossil arthropods in Europe and North America [5-8], little is known about the typical Asian (Laurasia-originated) arthropod biota. Here, we report a unique amber biota (50-53 million years ago) from the Lower Eocene of Fushun in northeastern China, which fills a large biogeographic gap in Eurasia. Fushun amber is derived from cupressaceous trees, as determined by gas chromatography-mass spectrometry, infrared spectroscopy, and paleobotanical observations. Twenty-two orders and more than 80 families of arthropods have been reported so far, making it among the most diverse amber biotas. Our results reveal that an apparent radiation of ecological keystone insects, including eusocial, phytophagous, and parasitoid lineages, occurred at least during the Early Eocene Climatic Optimum. Some insect taxa have close phylogenetic affinities to those from coeval European ambers, showing a biotic interchange between the eastern and western margins of the Eurasian landmass during the Early Paleogene. • A unique amber biota is reported from the Early Eocene of Fushun, China • The paleobiota is among the most diverse amber biotas • Fushun amber is derived from cupressaceous trees • Biotic interchange occurred between Europe and Asia during the Early Paleogene Wang et al. report a unique amber biota (50-53 million years ago) from the Lower Eocene of Fushun in northeastern China, which fills a large biogeographic gap in Eurasia. The paleobiota is among the most diverse amber biotas and indicates a biotic interchange between Europe and Asia during the Early Paleogene. [ABSTRACT FROM AUTHOR]

Amber preserves an exceptional record of tiny, soft-bodied organisms and chemical environmental signatures, elucidating the evolution of arthropod lineages and the diversity, ecology, and biogeochemistry of ancient ecosystems. However, globally, fossiliferous amber deposits are rare in the latest Cretaceous and surrounding the Cretaceous-Paleogene (K-Pg) mass extinction. 1,2,3,4,5 This faunal gap limits our understanding of arthropod diversity and survival across the extinction boundary. 2,6 Contrasting hypotheses propose that arthropods were either relatively unaffected by the K-Pg extinction or experienced a steady decline in diversity before the extinction event followed by rapid diversification in the Cenozoic. 2,6 These hypotheses are primarily based on arthropod feeding traces on fossil leaves and time-calibrated molecular phylogenies, not direct observation of the fossil record. 2,7 Here, we report a diverse amber assemblage from the Late Cretaceous (67.04 ± 0.16 Ma) of the Big Muddy Badlands, Canada. The new deposit fills a critical 16-million-year gap in the arthropod fossil record spanning the K-Pg mass extinction. Seven arthropod orders and at least 11 insect families have been recovered, making the Big Muddy amber deposit the most diverse arthropod assemblage near the K-Pg extinction. Amber chemistry and stable isotopes suggest the amber was produced by coniferous (Cupressaceae) trees in a subtropical swamp near remnants of the Western Interior Seaway. The unexpected abundance of ants from extant families and the virtual absence of arthropods from common, exclusively Cretaceous families suggests that Big Muddy amber may represent a yet unsampled Late Cretaceous environment and provides evidence of a faunal transition before the end of the Cretaceous. • Big Muddy amber is the most diverse amber fauna close to the K-Pg mass extinction • The deposit was produced in an ancient subtropical swamp near remnants of a marine seaway • Two partial crown ants are preserved, filling a 16-million-year gap in the ant fossil record • The assemblage suggests a faunal turnover among insects prior to the K-Pg mass extinction Loewen et al. describe the most diverse amber deposit near the end-Cretaceous mass extinction. This newly discovered deposit, formed 1 million years before the extinction event, supports a faunal turnover among insects prior to the impact. Common Cretaceous insect families and genera appear to be replaced by modern taxa for lineages such as ants. [ABSTRACT FROM AUTHOR]

Insects comprise over half of all described animal species. Together with the Protura (coneheads), Collembola (springtails) and Diplura (two-pronged bristletails), insects form the Hexapoda, a terrestrial arthropod lineage characterised by possessing six legs. Exponential growth of genome-scale data for the hexapods has substantially altered our understanding of the origin and evolution of insect biodiversity. Phylogenomics has provided a new framework for reconstructing insect evolutionary history, resolving their position among the arthropods and some long-standing internal controversies such as the placement of the termites, twisted-winged insects, lice and fleas. However, despite the greatly increased size of phylogenomic datasets, contentious relationships among key insect clades remain unresolved. Further advances in insect phylogeny cannot rely on increased depth and breadth of genome and taxon sequencing. Improved modelling of the substitution process is fundamental to countering tree-reconstruction artefacts, while gene content, modelling of duplications and deletions, and comparative morphology all provide complementary lines of evidence to test hypotheses emerging from the analysis of sequence data. Finally, the integration of molecular and morphological data is key to the incorporation of fossil species within insect phylogeny. The emerging integrated framework of insect evolution will help explain the origins of insect megadiversity in terms of the evolution of their body plan, species diversity and ecology. Future studies of insect phylogeny should build upon an experimental, hypothesis-driven approach where the robustness of hypotheses generated is tested against increasingly realistic evolutionary models as well as complementary sources of phylogenetic evidence. Davide Pisani and colleagues review our current understanding of insect phylogeny, remaining challenges and how to tackle them. [ABSTRACT FROM AUTHOR]

One of the most important trophic interactions today is that between insects and their floral hosts. This biotic association is believed to have been critical to the radiation of flowering plants and many pollinating insect lineages over the last 120 million years (Ma). Trophic interactions among fossil organisms are challenging to study, and most inferences are based on indirect evidence. Fossil records providing direct evidence for pollen feeding, i.e., fossil stomach and gut contents, are exceptionally rare. 1,2 Such records have the potential to provide information on aspects of animal behavior and ecology as well as plant-animal interactions that are sometimes not yet recognized for their extant relatives. The dietary preferences of short-proboscid nemestrinids are unknown, and pollinivory has not been recorded for extant Nemestrinidae. 3 We analyzed the contents of the conspicuously swollen abdomen of an ca. 47.5 Ma old nemestrinid fly of the genus Hirmoneura from Messel, Germany, with photogrammetry and state-of-the-art palynological methods. The fly fed on pollen from at least four plant families—Lythraceae, Vitaceae, Sapotaceae, and Oleaceae—and presumably pollinated flowers of two extant genera, Decodon and Parthenocissus. We interpret the feeding and foraging behavior of the fly, reconstruct its preferred habitat, and conclude about its pollination role and importance in paratropical environments. This represents the first evidence that short-proboscid nemestrinid flies fed, and possibly feed to this day, on pollen, demonstrating how fossils can provide vital information on the behavior of insects and their ecological relationships with plants. [Display omitted] • A newly described fossil nemestrinid fly preserves its last pollen meal in its crop • Analysis of crop content reveals consumption of pollen of mainly two plant genera • Inferences on foraging and feeding behavior can be drawn from the fossil • Implications of similar feeding behavior can be deduced for extant relatives Direct evidence for pollen feeding is very rare in the fossil record. Wedmann et al. analyze the last meal of pollen of a fossil tangle-veined fly and infer on its ecology and behavior. [ABSTRACT FROM AUTHOR]

Female mosquitoes are among the most notorious blood-feeding insects, sometimes causing severe allergic responses or vectoring a variety of microbial pathogens. 1,2 Hematophagy in insects is likely a feeding shift from plant fluids, with the piercing-sucking mouthparts serving as suitable exaptation for piercing vertebrates' skin. The origins of these habits are mired in an often-poor fossil record for many hematophagous lineages, 3,4 particularly those of sufficient age, as to give insights into the paleoecological context in which blood feeding first appeared or even to arrive at gross estimates as to when such shifts have occurred. This is certainly the case for mosquitoes, a clade estimated molecularly to date back to the Jurassic. 5 The known Mesozoic Culicidae are Late Cretaceous, assigned to the modern Anophelinae or to the extinct Burmaculicinae, sister to other Culicidae, all with mouthparts of a modern type. Here, we report the discovery, in Lower Cretaceous amber from Lebanon, of two conspecific male mosquitoes unexpectedly with piercing mouthparts, armed with denticulate sharp mandibles and laciniae. These male fossils were likely hematophagous. They represent a lineage that diverged earlier than Burmaculicinae, extending the definitive occurrence of the family into the Early Cretaceous and serving to narrow the ghost-lineage gap for mosquitoes. [Display omitted] • Earliest-diverging lineage and oldest occurrence of mosquitoes • Male mosquito with well-developed, denticulate, and hematophagous-type mouthparts • New extinct subfamily of mosquitoes Azar et al. describe the earliest known fossil mosquito from Lower Cretaceous Lebanese amber. A new, early diverging subfamily of mosquitoes (Culicidae), the species is represented by two conspecific males with well-developed, denticulate, and hematophagous-type mouthparts, indicating that these males were likely blood feeders. [ABSTRACT FROM AUTHOR]

Summary Termitophiles, symbionts that live in termite nests, include a wide range of morphologically and behaviorally specialized organisms. Complex adaptive mechanisms permit these animals to integrate into societies and to exploit their controlled physical conditions and plentiful resources, as well as to garner protection inside termite nests. An understanding of the early evolution of termitophily is challenging owing to a scarcity of fossil termitophiles, with all known reliable records occurring from the Miocene (approximately 19 million years ago [mya]) [ 1–6 ], and an equivocal termitophile belonging to the largely free-living Mesoporini from the mid-Cretaceous [ 7 ]. Here we report the oldest, morphologically specialized, and obligate termitophiles from mid-Cretaceous Burmese amber (99 mya). Cretotrichopsenius burmiticus gen. et sp. nov. belongs to Trichopseniini, a group of distinctive termitophilous aleocharine rove beetles, all of which possess specialized swollen or horseshoe-crab-shaped body plans. Cretotrichopsenius display the protective horseshoe-crab-shaped body form typical of many modern termitophiles, with concealed head and antennae and strong posteriorly directed abdominal setae. Cretotrichopsenius represent the earliest definitive termitophiles, shedding light on host associations in the early evolution of termite societies. The fossil reveals that ancient termite societies were quickly invaded by beetles and by multiple independent lineages of social parasites over the subsequent eons. [ABSTRACT FROM AUTHOR]

Summary The appearance of wings in insects, early in their evolution [ 1 ], has been one of the more critical innovations contributing to their extraordinary diversity. Despite the conspicuousness and importance of wings, the origin of these structures has been difficult to resolve and represented one of the “abominable mysteries” in evolutionary biology [ 2 ]. More than a century of debate has boiled the matter down to two competing alternatives—one of wings representing an extension of the thoracic notum, the other stating that they are appendicular derivations from the lateral body wall. Recently, a dual model has been supported by genomic and developmental data [ 3–6 ], representing an amalgamation of elements from both the notal and pleural hypotheses. Here, we reveal crucial information from the wing pad joints of Carboniferous palaeodictyopteran insect nymphs using classical and high-tech techniques. These nymphs had three pairs of wing pads that were medially articulated to the thorax but also broadly contiguous with the notum anteriorly and posteriorly (details unobservable in modern insects), supporting their overall origin from the thoracic notum as well as the expected medial, pleural series of axillary sclerites. Our study provides support for the formation of the insect wing from the thoracic notum as well as the already known pleural elements of the arthropodan leg. These results support the unique, dual model for insect wing origins and the convergent reduction of notal fusion in more derived clades, presumably due to wing rotation during development, and they help to bring resolution to this long-standing debate. [ABSTRACT FROM AUTHOR]

Summary Insects exhibit a wide diversity of anatomical specializations in their adult and immature stages associated with particular aspects of their biology. The order Neuroptera (lacewings, antlions, and their relatives) are a moderately diverse lineage of principally predatory animals, at least in their immature stages, as all have a modified piercing-sucking mandible-maxillary complex that allows them to drain fluids from their prey. As such, the larvae of various groups have evolved unique anatomical and behavioral specializations for approaching and subduing their prey, particularly the green lacewings (Chrysopidae), where immatures are also adept at camouflage [ 1–4 ]. Here we report the discovery of a unique mode of life among mid-Cretaceous mesochrysopids, an early stem group to modern green lacewings [ 5–7 ] exhibiting a combination of morphological modifications in both adults and larvae unknown among living and fossil Neuroptera, even across winged insects. The new mesochrysopids exhibit a uniquely prolonged thorax, elongate legs, and dramatically reduced hind wings in adults, and larvae have extremely elongate, slender legs with pectinate pretarsal claws and lacking trumpet-shaped empodia. The peculiarities of the larvae include features principally found in spider-associated insect groups, implying that these lacewings were early specialists on web-spinning spiders, either as active predators or kleptoparasites. This reveals a dramatic and ancient degree of ecological refinement in a major lineage of insect predators, for a food resource otherwise not utilized by most lacewings. [ABSTRACT FROM AUTHOR]

The Late Paleozoic acquisition of wings in insects represents one of the key steps in arthropod evolution. While the origin of wings has been a contentious matter for nearly two centuries, recent evolutionary developmental studies suggest either the participation of both tergal and pleural tissues in the formation of wings 1 or wings originated from exites of the most proximal leg podite incorporated into the insect body wall. 2 The so-called "dual hypothesis" for wing origins finds support from studies of embryology, evo-devo, and genomics, although the degree of the presumed contribution from tergal and pleural tissues differ. 3–6 Ohde et al., 7 confirmed a major role for tergal tissue in the formation of the cricket wing and suggested that "wings evolved from the pre-existing lateral terga of a wingless insect ancestor." Additional work has focused on identifying partial serially homologous structures of wings on the prothorax 8,9 and abdominal segments. 10 Thus, several studies have suggested that the prothoracic horns in scarab beetles, 9 gin traps of tenebrionid and scarab beetle pupae, 11,12 or abdominal tracheal gills of mayfly larvae 1,13 evolved from serial homologues of wings. Here, we present critical information from abdominal lateral outgrowths (flaps) of Paleozoic palaeodictyopteran larvae, which show comparable structure to thoracic wings, consisting of cordate lateral outgrowths antero-basally hinged by muscle attachments. These flaps therefore most likely represent wing serial homologues. The presence of these paired outgrowths on abdominal segments I–IX in early diverging Pterygota likely corresponds to crustacean epipods 14,15 and resembles a hypothesized ancestral body plan of a "protopterygote" model. [Display omitted] • Palaeodictyopteran abdominal segments show serially homologous structures of wings • Cordate lateral structures (flaps) in larvae were fused to tergum covering the hinge • Adults shared these abdominal flaps with larvae either functionally or vestigially • Flap functions remain unknown, perhaps performing locomotion, respiration, or sensory Prokop et al. demonstrate serial homologues of thoracic wings on abdominal segments I–IX in the form of hinged lateral outgrowths preserved in Paleozoic palaeodictyopteran larvae. These flaps could relate to locomotive, respiratory, or sensory functions. This body plan resembles the "protopterygote" model of a hypothetical ancestor for Pterygota. [ABSTRACT FROM AUTHOR]

Summary Blood-feeding insects, as vectors of disease for humans and livestock alike, have garnered significant interest [ 1, 2 ], but our understanding of their early evolution is hindered by the scarcity of available material and the difficulty in distinguishing early hematophages from non-blood-feeding relatives. Here, we report a new family of true bugs including two new genera and species from the Early Cretaceous Yixian Formation in Northeastern China. By utilizing geochemical methods for determining their diets and combining morphological and taphonomic data, we demonstrate that these new species represent the earliest evidence of blood feeding among true bugs, extending the geological record of such lineages by approximately 30 million years. Remarkably, one of the bugs appears to have perished immediately following a blood meal, which may have been from coexisting mammals, birds, or avian-related dinosaurs. These records expand the phylogenetic and ecological diversity of blood-feeding insects in the Early Cretaceous, enriching our knowledge of paleoecological associations in these ancient environments. [ABSTRACT FROM AUTHOR]

Summary Cycads, unlike modern wind-pollinated conifers and Ginkgo , are unusual in that they are an ancient group of gymnosperms pollinated by insects [ 1–3 ]. Although it is well documented that cycads were diverse and abundant during the mid-Mesozoic, little is known about their biogeography and pollination before the rise of angiosperms. Direct fossil evidence illuminating the evolutionary history of cycads is extremely rare [ 4, 5 ]. Here we report a specialized beetle-mediated pollination mode from the mid-Cretaceous of Myanmar, wherein a new boganiid beetle, Cretoparacucujus cycadophilus , with specialized pollen-feeding adaptations in its mouthparts and legs, was associated with many pollen grains of Cycadopites. Phylogenetic analyses indicate Cretoparacucujus as a sister group to the extant Australian Paracucujus , which pollinate the cycad Macrozamia riedlei. Our discovery, along with the current disjunct distribution of related beetle-herbivore (tribe Paracucujini) and cycad-host (tribe Encephalarteae) pairs in South Africa and Australia, indicate a probable ancient origin of beetle pollination of cycads at least in the Early Jurassic, long before angiosperm dominance and the radiation of flowering-plant pollinators later in the Cretaceous. Highlights • A specialized beetle-mediated pollination mode is reported from Burmese amber • The mid-Cretaceous boganiid beetle has many pollen-feeding adaptations • The fossil boganiid was probably a pollinator of Encephalarteae cycads • This suggests a probable ancient origin of beetle pollination of cycads in the Mesozoic Cai et al. report a new mid-Cretaceous boganiid beetle with specialized pollen-feeding adaptations. The phylogenetic analyses and associated pollen grains indicate that it was probably a pollinator of early cycads. This suggests an ancient origin of beetle pollination of cycads long before the rise of flowering plants. [ABSTRACT FROM AUTHOR]

Summary Camouflage and mimicry are staples among predator-prey interactions, and evolutionary novelties in behavior, anatomy, and physiology that permit such mimesis are rife throughout the biological world [ 1, 2 ]. These specializations allow for prey to better evade capture or permit predators to more easily approach their prey, or in some cases, the mimesis can serve both purposes. Despite the importance of mimesis and camouflage in predator-avoidance or hunting strategies, the long-term history of these traits is often obscured by an insufficient fossil record. Here, we report the discovery of Upper Cretaceous (approximately 100 million years old) green lacewing larvae (Chrysopoidea), preserved in amber from northern Myanmar, anatomically modified to mimic coeval liverworts. Chrysopidae are a diverse lineage of lacewings whose larvae usually camouflage themselves with a uniquely constructed packet of exogenous debris, conveying greater stealth upon them as they hunt prey such as aphids as well as evade their own predators [ 3, 4 ]. However, no lacewing larvae today mimic their surroundings. While the anatomy of Phyllochrysa huangi gen. et sp. nov. allowed it to avoid detection, the lack of setae or other anatomical elements for entangling debris as camouflage means its sole defense was its mimicry, and it could have been a stealthy hunter like living and other fossil Chrysopoidea or been an ambush predator aided by its disguise. The present fossils demonstrate a hitherto unknown life-history strategy among these “wolf in sheep’s clothing” predators, one that apparently evolved from a camouflaging ancestor but did not persist within the lineage. [ABSTRACT FROM AUTHOR]

Summary In a recent Current Biology paper [1] , we reported the oldest, morphologically specialized, and obligate termitophiles, Cretotrichopsenius burmiticus ( Figure 1 , left), from mid-Cretaceous Burmese amber, about 99 million years old. Cretotrichopsenius , belonging to the obligately termitophilous rove beetle tribe Trichopseniini, display the protective horseshoe-crab-shaped body typical of many extant termitophiles. However, the termitophilous lifestyle of Cretotrichopsenius is being questioned by Yamamoto et al. [2] based on their representation of the termitophile-related features and premature and presumptive phylogenetic placement of Cretotrichopsenius within Trichopseniini. We stand by our interpretation that Cretotrichopsenius are obligate termitophiles, and Mesosymbion [3] , a member of the largely free-living Mesoporini, are not necessarily termitophilous. [ABSTRACT FROM AUTHOR]

Competing Interests: The authors declare no competing interests.

This protocol explains how to extract pollen from fossil insects with subsequent descriptions of pollen treatment. We also describe how to document morphological and ultrastructural features with light-microscopy and electron microscopy. It enables a taxonomic assignment of pollen that can be used to interpret flower-insect interactions, foraging and feeding behavior of insects, and the paleoenvironment. The protocol is limited by the state of the fossil, the presence/absence of pollen on fossil specimens, and the availability of extant pollen for comparison. For complete details on the use and execution of this protocol, please refer to Wappler et al. (2015), Ulrich and Grímsson (2020), and Wedmann et al. (2021)., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

Mimicry is ubiquitous in nature, yet understanding its origin and evolution is complicated by the scarcity of exceptional fossils that enable behavioral inferences about extinct animals. Here we report bizarre true bugs (Hemiptera) that closely resemble beetles (Coleoptera) from mid-Cretaceous amber. The unusual fossil bugs are described as Bersta vampirica gen. et sp. nov. and Bersta coleopteromorpha gen. et sp. nov. and are placed into a new family, Berstidae fam. nov. The specialized mouthparts of berstids indicate that they were predaceous on small arthropods. Their striking beetle-like appearance implies that they were either involved in defensive mimicry or mimicked beetles to attack unsuspecting prey. The latter would represent the first case of aggressive mimicry in the invertebrate fossil record. These findings enrich our understanding of the paleoecological associations and extinct behavioral strategies of Mesozoic insects., Competing Interests: Declaration of Interests The authors declare no competing interests., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Termite success is inexorably linked to their diet and symbiotic cellulolytic intestinal microorganisms. A new study reveals that soil feeding may have triggered a turnover in intestinal symbionts, rather than ectosymbiont cultivation, allowing termites to achieve ecological dominance., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Jakub Prokop and Michael Engel introduce palaeodictyopterids, a very diverse extinct lineage of insects., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Ants comprise one lineage of the triumvirate of eusocial insects and experienced their early diversification within the Cretaceous [1-9]. Their ecological success is generally attributed to their remarkable social behavior. Not all ants cooperate in social hunting, however, and some of the most effective predatory ants are solitary hunters with powerful trap jaws [10]. Recent evolutionary studies predict that the early branching lineages of extant ants formed small colonies of ground-dwelling, solitary specialist predators [2, 5, 7, 11, 12], while some Cretaceous fossils suggest group recruitment and socially advanced behavior among stem-group ants [9]. We describe a trap-jaw ant from 99 million-year-old Burmese amber with head structures that presumably functioned as a highly specialized trap for large-bodied prey. These are a cephalic horn resulting from an extreme modification of the clypeus hitherto unseen among living and extinct ants and scythe-like mandibles that extend high above the head, both demonstrating the presence of exaggerated morphogenesis early among stem-group ants. The new ant belongs to the Haidomyrmecini, possibly the earliest ant lineage [9], and together these trap-jaw ants suggest that at least some of the earliest Formicidae were solitary specialist predators. With their peculiar adaptations, haidomyrmecines had a refined ecology shortly following the advent of ants., (Copyright © 2016 Elsevier Ltd. All rights reserved.)