Swarming caddisflies in the mid-cretaceous.

Swarming, as a special form of mating aggregation, is most noteworthy in insects of the orders Ephemeroptera, Diptera, and Trichoptera. Swarming in extant trichopterans is well understood in terms of sex composition, specific mating behaviors, and functional morphological specializations of adults, but an exploration of the evolution of such aggregative behaviors is hampered by the dearth of available examples from the fossil record as well as the ability to reliably distinguish the few gatherings as the result of swarming relative to other taphonomic or behavioral factors. Herein we describe five new fossil species of caddisflies preserved in mid-Cretaceous amber from Myanmar, all preserved as large aggregations. Monospecific aggregations of these five new species can be positively identified as swarms based on morphological traits of wing shape, as well as the presence of particular forms of sexual dimorphism. Results of a phylogenetic reconstruction of both molecular and morphological data as well as ancestral-trait reconstructions and tip-dating analyses indicate that swarming was likely present in the Triassic as a feature of the trichopteran groundplan. Since most Mesozoic insectivorous predators were diurnal based on morphological evidence, largely nocturnal caddisflies would have been freed from such pressures. The phylogeny also shows a correlation between the rise of nocturnal bat predators from the Paleocene or early Eocene and the repeated loss of swarming from various clades of caddisflies, revealing the potential impact of bat predation on reshaping the behavioral landscape of Trichoptera during the Cenozoic.

Cretaceous crown male ant reveals the rise of modern lineages.

Most described Mesozoic ants belong to stem groups that existed only during the Cretaceous period. Previously, the earliest known crown ants were dated to the Turonian (Late Cretaceous, ca. 94-90 million years ago (Ma)) deposits found in the USA, Kazakhstan, and Botswana. However, the recent discovery of an alate male ant in Kachin amber from the earliest Cenomanian (ca. 99 Ma), representing a new genus and species, Antiquiformica alata, revises the narrative on ant diversification. Antiquiformica can be distinctly differentiated from all known male stem ants by its geniculate antennae with elongated scape, extending far beyond the occipital margin of the head and half the length of the funiculus, as well as its partly reduced forewing venation. Furthermore, the combination of a one-segmented waist with a well-developed node, elongated scape extending beyond the occipital margin, and reduced forewing venation, particularly the completely reduced m-cu and rs-m crossveins and absence of rm and mcu closed cells, firmly places the fossil within the extant subfamily Formicinae. Fourier transform infrared spectroscopy (FTIR) confirmed that the amber containing Antiquiformica alata originated from the Kachin mines in Myanmar. This discovery significantly revises our understanding of the early evolution of Formicinae. The presence of Antiquiformica in Cenomanian amber indicates that the subfamily Formicinae emerged at least by the start of the Late Cretaceous, with crown ants likely originating earlier during the earliest Cretaceous or possibly the Late Jurassic, although paleontological evidence is lacking to support the latter hypothesis.

A New Genus of Praeaulacidae (Hymenoptera: Evanioidea) from Mid-Cretaceous Kachin Amber: Insights into a Putative New Praeaulacinae Subclade.

A new praeaulacid genus and species, Azygdellitha nova gen. et sp. nov., is described and illustrated based on a male specimen from mid-Cretaceous Kachin amber from Hukawng Valley, Myanmar. This newly discovered taxon increased the diversity of praeaulacid wasps during the Cretaceous period. While this new taxon shares similarities of wing venation with most species of the subfamily Praeaulacinae, it strongly differs from that of three genera previously described from mid-Cretaceous Kachin amber: Mesevania, Paleosyncrasis, and Praegastrinus. We explore the possibility that these genera constitute a distinct tribe within the Praeaulacinae, distinguished by their wing venation. We provide illustrations and emphasize the potentially diagnostic traits supporting this classification.

Specialized ovipositor sensilla of Cretaceous wasps (Insecta: Hymenoptera) possibly reveal a unique way of host detection.

Insects have evolved complex sensory systems that are important for feeding, defence and reproduction. Parasitoid wasps often spend much time and effort in searching for concealed hosts with the help of specialized sensilla. However, the early evolution of such behaviour and sensilla is poorly known. We describe two fossil female wasps, †Tichostephanus kachinensis sp. nov. and †Tichostephanus longus sp. nov., from mid-Cretaceous Kachin amber. Phylogenetic analyses based on morphological data retrieved †Tichostephanus as deeply nested within Evanioidea and closely related to extant Gasteruptiidae and Evaniidae. Both of these Cretaceous wasps possess features, e.g. coronal tubercles and flexible ovipositor sheaths, that indicate that they might have laid eggs in wood where their larvae possibly parasitized insect larvae. They have a peculiar and unique 'bottle brush' of sensilla close to the apex of their ovipositor sheaths, which has not been observed in any extant parasitoid wasps. These sensilla comprise many regularly arranged plate-shaped setae, attached in relatively large sockets and with rows of longitudinal ridges. Such specialized sensilla perhaps served to enhance the ability to detect hosts inside wood.

Primitive new termites (Blattodea, Termitoidae) in Cretaceous amber from Myanmar.

Mastotermitidae, the first-diverging extant family of termites, has only one relic extant species; however, this family had greater richness during the Mesozoic and Cenozoic eras. Fossil termites from the Cretaceous provide information on the early evolution of termites and the transition between extinct families. Herein, two new Mastotermitidae species found in upper Cretaceous (Cenomanian) Kachin amber are reported. One is a female imago described as Angustitermesreflexusgen. et sp. nov. and assigned to the subfamily Mastotermitinae. The other is Mastotermesreticulatussp. nov., which is described from an isolated forewing. With the comparison especially of the antenna and venation, these new mastotermitids further increase our knowledge of the diversity and morphology of Mastotermitidae during the Mesozoic.

New stenurothripid thrips from mid-Cretaceous Kachin amber (Thysanoptera, Stenurothripidae).

Hitherto, only two species of the thysanopteran suborder Terebrantia have been reported from mid-Cretaceous Kachin amber (Myanmar). This is here expanded through the discovery of two new genera and species, described and figured as Parallelothripsseparatusgen. et sp. nov. and Didymothripsabdominalisgen. et sp. nov., both of the family Stenurothripidae. Both taxa have key apomorphies of the Stenurothripidae, allowing for a confident assignment as to family. Both species have characteristic comb-like anteromarginal setae, which are discussed along with structural differences between the two sexes. Cycad pollen was found on the thrips' bodies, providing further evidence that Thysanoptera were pollinators of gymnosperms during the mid-Cretaceous.

Stem chewing lice on Cretaceous feathers preserved in amber.

Phthirapteran lice (true lice or parasitic lice) are a major group of ectoparasitic insects living on their bird or mammal hosts during their entire life cycle.1 Due to their highly specialized lifestyles, they are extremely poorly represented in fossil records.2 Molecular clock estimations have speculated extensively about the origin time of parasitic lice,3,4 yet none have been confirmed unequivocally. Herein, we report a new family of stem chewing lice, based on two adult insects associated with several semiplume feathers preserved within a piece of Kachin amber from the mid-Cretaceous. They display some defining characteristics of the Amblycera, an early-diverging lineage of the crown lice group. These features include a wingless body, chewing mouthparts, narrow and small thorax, and short tarsus with elongated euplantulae. Our phylogenetic analysis places the new taxa in the Amblycera, and the discovery thus pushes back the lice fossil records by at least 55 million years. Furthermore, the new specimens show primitive characters such as compressed and club-shaped terminal segments of antennae, maxillary and labial palps, and unmodified femora of hind legs, providing key information for the evolutionary relationship between free-living booklice and parasitic lice. This suggests that some ectoparasitic characters defining the crown lice group might have evolved among amblyceran and non-amblyceran lice in parallel. These newly described fossil specimens imply at least a Cretaceous age of Phthiraptera.

Middle Jurassic insect mines on gymnosperms provide missing links to early mining evolution.

We investigated the mining mode of insect feeding, involving larval consumption of a plant's internal tissues, from the Middle Jurassic (165 million years ago) Daohugou locality of Northeastern China. Documentation of mining from the Jurassic Period is virtually unknown, and results from this time interval would address mining evolution during the temporal gap of mine-seed plant diversifications from the previous Late Triassic to the subsequent Early Cretaceous. Plant fossils were examined with standard microscopic procedures for herbivory and used the standard functional feeding group-damage-type system of categorizing damage. All fossil mines were photographed and databased. We examined 2014 plant specimens, of which 27 occurrences on 14 specimens resulted in eight, new, mine damage types (DTs) present on six genera of bennettitalean, ginkgoalean, and pinalean gymnosperms. Three conclusions emerge from this study. First, these mid-Mesozoic mines are morphologically conservative and track plant host anatomical structure rather than plant phylogeny. Second, likely insect fabricators of these mines were three basal lineages of polyphagan beetles, four basal lineages of monotrysian moths, and a basal lineage tenthredinoid sawflies. Third, the nutrition hypothesis, indicating that miners had greater access to nutritious, inner tissues of new plant lineages, best explains mine evolution during the mid-Mesozoic.

The associated evolution of raptorial foreleg and mantispid diversification during 200 million years.

Mantispidae have developed multidimensional specializations of predation that are leveraged by trade-offs involving attack properties, which is revealed by interdisciplinary analyses of phylogeny, morphometrics, and mechanical modeling. The lineage diversification was stimulated by its raptorial foreleg evolution, and was influenced by the ecosystem of corresponding periods, involving biotic and physical factors.

A new method for examining the co-occurrence network of fossil assemblages.

Currently, studies of ancient faunal community networks have been based mostly on uniformitarian and functional morphological evidence. As an important source of data, taphonomic evidence offers the opportunity to provide a broader scope for understanding palaeoecology. However, palaeoecological research methods based on taphonomic evidence are relatively rare, especially for body fossils in lacustrine sediments. Such fossil communities are not only affected by complex transportation and selective destruction in the sedimentation process, they also are strongly affected by time averaging. Historically, it has been believed that it is difficult to study lacustrine entombed fauna by a small-scale quadrat survey. Herein, we developed a software, the TaphonomeAnalyst, to study the associational network of lacustrine entombed fauna, or taphocoenosis. TaphonomeAnalyst allows researchers to easily perform exploratory analyses on common abundance profiles from taphocoenosis data. The dataset for these investigations resulted from fieldwork of the latest Middle Jurassic Jiulongshan Formation near Daohugou Village, in Ningcheng County of Inner Mongolia, China, spotlighting the core assemblage of the Yanliao Fauna. Our data included 27,000 fossil specimens of animals from this deposit, the Yanliao Fauna, whose analyses reveal sedimentary environments, taphonomic conditions, and co-occurrence networks of this highly studied assemblage, providing empirically robust and statistically significant evidence for multiple Yanliao habitats.

Independent wing reductions and losses among stick and leaf insects (Phasmatodea), supported by new Cretaceous fossils in amber.

BACKGROUND: Phasmatodea (stick and leaf insects) play a central role on the debate regarding wing reduction and loss, and its wings are putative reacquisition from secondarily wingless ancestors based solely on extant species. A pivotal taxon in this respect is the species-poor Timematodea, consisting of approximately 21 wingless extant species, which form the sister group of all remaining winged or wingless stick and leaf insects, the Euphasmatodea. RESULTS: Herein, the new fossils of Timematodea from mid-Cretaceous Kachin amber are reported, with winged and wingless species co-occurring. The palaeogeographic distributions of all fossils of Holophasmatodea are summarized, showing their wide paleo-distributions. The phylogenetic analysis based on morphological characters confirms the earliest-diverging lineage of winged Breviala cretacea gen. et sp. nov. in Timematodea, and the possible relationships among all families of Holophasmatodea. These are critical for the reconstruction of patterns of wing evolution in early Phasmatodea. CONCLUSIONS: The new fossils suggest that Timematodea once had wings, at least during the mid-Cretaceous. The palaeogeographic occurrences imply that Timematodea probably have been widely distributed since at least the Jurassic. The phylogenetic analysis with the ancestral-state reconstruction of wings indicates that the common ancestors of Holophasmatodea were winged, the reductions and losses of wings among Timematodea and Euphasmatodea have occurred independently since at least the Cretaceous, and the reduction or loss of the forewing earlier than the hind wings.

New Earwigs from the Middle Jurassic Jiulongshan Formation of Northeastern China (Dermaptera).

Two new genera and species of Dermaptera are described from the Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China: Applanatiforceps angustus gen. et sp. nov. in the archidermapteran family Protodiplatyidae, and Ekpagloderma gracilentum gen et sp. nov. in the eodermapteran family Semenoviolidae. Applanatiforceps shares the typical characters of the extinct suborder Archidermaptera (e.g., pentamerous meta tarsi, filiform and multimerous cerci) and externalized ovipositor. The family identity of the Protodiplatyidae can be further distinguished by comparing this new genus with other genera of the Protodiplatyidae. As a result of its large compound eyes, tegmina without venation, body sparsely setose, legs rather short and slender, and shape of the veinless tegmina, Ekpagloderma is classified in the subfamily Aglyptodermatinae. Ekpagloderma not only has the typical features of the Aglyptodermatinae, but also exhibits a more primitive slender segmented cerci, which is different from all other genera of Eodermaptera. In fact, the diversity of Eodermaptera as known today indicates some of the challenges in understanding the suborder and whether or not it is monophyletic as historically construed, or if the separation of Turanodermaptera is justified.

New Osmylopsychopid Taxa from the Middle Jurassic of Northeastern China (Neuroptera: Osmylopsychopidae).

One new genus with four new species sharing the similar character of a forewing length of ca. 10 mm, namely, Minipsychops spasulus gen. et sp. nov., Minipsychops polychotomus sp. nov., Minipsychops densus sp. nov., and Minipsychops unicus sp. nov., are described from the Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia in China. These new insects can be attributed to Osmylopsychopidae for their distinctive configuration of costal space and the venations of RP1 and Cu. Compared with the typically medium to large body sizes of known osmylopsychopids, these new Middle Jurassic taxa of a particularly miniaturized lineage not only enrich the species diversity of Osmylopsychopidae, but also enhance our understanding of the historical evolution of these poorly known lacewings.

A Cretaceous Chafer Beetle (Coleoptera: Scarabaeidae) with Exaggerated Hind Legs-Insight from Comparative Functional Morphology into a Possible Spring Movement.

The phenomenon of exaggerated morphological structures has fascinated people for centuries. Beetles of the family Scarabaeidae show many very diverse exaggerated characters, for example, a variety of horns, enlarged mandibles or elongated antennal lamellae. Here, we report a new Mesozoic scarab, Antiqusolidus maculatus gen. et sp. n. from the Lower Cretaceous Yixian Formation (~125 Ma), which has unusually robust and structured hind legs with greatly enlarged spurs and a unique elongated apical process. Based on simulations and finite element analyses, the function of these structures is hypothesized to support springing to aid movement and fighting. Based on available morphological characters, we performed phylogenetic analyses (maximum parsimony) of the main subfamilies and families of Scarabaeoidea. The results support the placement of Antiqusolidus gen. n. as a sister group of Rutelinae within the phytophagous lineage of pleurostict Scarabaeidae. Furthermore, the unusual delicate color marking patterns in the fossil specimens suggest that the new species might have been diurnal and potentially visited the leaves or flowers of Early Cretaceous plants. This morphological and functional study on this extinct scarab species provides new sights into exaggerated structures in Mesozoic insects.

A wide hybrid zone mediated by precipitation contributed to confused geographical structure of Scutiger boulengeri.

Confused geographical structure of a population and mitonuclear discordance are shaped by a combination of rapid changes in population demographics and shifts in ecology. In this study, we generated a time-calibrated phylogeny of Scutiger boulengeri, an endemic Xizang alpine toad occurring in mountain streams on the Qinghai-Xizang (Tibet) Plateau (QTP). Based on three mitochondrial DNA (mtDNA) genes, eight clades were assigned to three deeply divergent lineages. Analysis of nuclear DNA (nuDNA) genes revealed three distinct clusters without geographic structure, indicating significantly high rates of gene flow. Coalescent theory framework analysis (approximate Bayesian computation model DIYABC and Migrate-N) suggested that divergence of the main intraspecific clusters was the result of hybridization after secondary contact in the Holocene around 0.59 million years ago (Ma). The ratio of mtDNA F ST (fixation index) to nuDNA F ST was 2.3, thus failing to show male-biased dispersal. Geographic cline analysis showed that a wide hybrid zone was initially established in southwestern China, without significant reproductive isolation but with strong introgression in S. boulengeri, suggesting high hybrid fitness. Furthermore, mtDNA genes exhibited isolation by distance (IBD) while nuDNA genes exhibited significant isolation by environment (IBE). Results suggested that mitonuclear discordance may have initially been caused by geographic isolation, followed by precipitation-mediated hybridization, producing a wide hybrid zone and geographic structure confusion of nuDNA genes in S. boulengeri. This study indicated that complicated historical processes may have led to specific genetic patterns, with a specific climate factor facilitating gene flow in the system.

New Pamphiliids with Varying Venations from Lower Cretaceous Yixian Formation of Northeast China (Hymenoptera, Pamphiliidae).

One new genus and three new species of Pamphiliidae, Dolicholyda obtusata gen. et sp. nov., Dolicholyda confluens sp. nov., and Dolicholyda angusta sp. nov. are described and illustrated. All of them were collected from the Lower Cretaceous Yixian Formation in Duolun County, Inner Mongolia, China. The new genus is established based on the following characters: body surface without punctations; forewing with pterostigma lanceolate and sclerotized around the margins; angle between 1-M and 1-Cu nearly 90°; cell 1mcu long and obviously longer than length of pterostigma. In most cases, the ap-Cu is present, and its length varied. Additionally, we revise the diagnostic characteristics of Juralydinae based on the new specimens. New findings enhance our understanding of the wing venation characteristics of fossil pamphiliids and expand the diversity of Pamphiliidae in the Mesozoic.

Early evolution of wing scales prior to the rise of moths and butterflies.

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.

Cretaceous lophocoronids with short proboscis and retractable female genitalia provide the earliest evidence for their feeding and oviposition habits.

We describe two new species of Lophocoronidae: Acanthocorona hedida Zhang, Shih and Engel sp. n. and Acanthocorona venulosa Zhang, Shih and Engel sp. n., and an undetermined specimen from mid-Cretaceous Kachin amber. Phylogenetic analysis of basal lepidopteran lineages, including three extinct families, was undertaken. The analysis supported monophyly of Glossata although internal relationships remain controversial. Acanthocorona and Lophocorona form a monophyletic group. It is likely that short and simply structured proboscides of Acanthocorona were used to sip water droplets, pollination drops from gymnosperms, nectar from early flowers, or sap from injured leaves. Both retracted and extended ovipositors are preserved in the material reported here, revealing their morphology and indicating that these Cretaceous lophocoronids inserted eggs into the tissues of their host plants.

Two New Fossil Sawflies of Pamphiliidae (Hymenoptera: Symphyta) from the Mesozoic of Northeastern China.

Two new species of Pamphiliidae, Scabolyda latusa sp. nov. and Scabolyda tenuis sp. nov. are described and illustrated from the late Middle Jurassic Jiulongshan Formation and the Lower Cretaceous Yixian Formation of northeastern China, respectively. A new specimen of Scabolyda orientalis Wang, Rasnitsyn, Shih and Ren, 2014 with distinct male genitalia is documented for the first time. Based on the specimens with new and distinct structures of legs, antennae, and genitalia, the morphological characters of Scabolyda are supplemented: antenna with ca. 13-14 flagellomeres; fore leg with tibia without pre-apical spur; hind leg nearly 0.6 times as long as the body, hind tarsal claw without setae and its inner tooth not developed. In addition, the tarsal claw characteristics found in the new species may suggest Scabolyda has a closer relationship with Cephalciinae, rather than with Pamphiliinae.

New Fossil Xyelidae (Hymenoptera: Symphyta) from the Mesozoic of Northeastern China.

One new genus and species, Leptoxyela eximia gen. et sp. nov., and one new species, Scleroxyela cephalota sp. nov., are described and illustrated based on two well-preserved compression fossils from the Lower Cretaceous Yixian Formation and the Middle Jurassic Jiulongshan Formation of China, respectively. Leptoxyela eximia gen. et sp. nov. is placed in the tribe Angaridyelini, 1966 and Scleroxyela cephalota sp. nov. in the tribe Xyeleciini Benson, 1945; while both tribes are in the subfamily Macroxyelinae Ashmead, 1898 of Xyelidae. A key to the genera of Angaridyelini is provided. In addition, we investigated various angles between Rs+M and 1-Rs for known fossil species of Macroxyelinae, and we found the angle and the length of 1-Rs are correlated; however, we could not see any correlation between the angles and the fossil ages even within a tribe. Furthermore, based on Sc2 connected to R before Rs, the angle between Rs+M and 1-Rs, and the length of the first flagellomere, we believe that the tribe Ceroxyelini may have only one genus of Ceroxyela, and suggest that Isoxyela and Sinoxyela should be transferred to Gigantoxyelini.