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While the monophyly of winged insects (Pterygota) is well supported, phylogenetic relationships among the most basal extant pterygote lineages are problematic. Ephemeroptera (mayflies) and Odonata (dragonflies) represent the two most basal extant lineages of winged insects, and determining their relationship with regard to Neoptera (remaining winged insects) is a critical step toward understanding insect diversification. A recent molecular analysis concluded that Paleoptera (Odonata + Ephemeroptera) is monophyletic. However, we demonstrate that this result is supported only under a narrow range of alignment parameters. We have further tested the monophyly of Paleoptera using additional sequence data from 18SrDNA, 28S rDNA, and Histone 3 for a broader selection of taxa and a wider range of analytical methodologies. Our results suggest that the current suite of molecular data ambiguously resolve the three basal winged insect lineages and do not provide independent confirmation of Odonata + Neoptera as supported via morphological data.

The earliest branching event in winged insects, one of the core problems regarding early insect evolution, was addressed using characters of the head. The head is arguably one of the most complex body regions in insects and the phylogenetic information content of its features has been demonstrated. In contrast, the wings and other body parts related to the flight apparatus and sperm transmission are not useful in the context of this problem, as the outgroups (silverfish and bristletails) are wingless and transmit spermatophores externally. Therefore, they show profound differences in the organization of the postcephalic body, and assessment of homology and subsequent phylogenetic analysis of features of these body regions is extremely difficult. The core of this study is the investigation of head structures of representatives of the major clades of dragonflies. A detailed description of the head of Lestes virens is presented and was used as a starting point for the compilation of a character set and a character state matrix for the entire Dicondylia (winged insects + silverfish), with a main focus on the placement of dragonflies and consequently the basal branching event within winged insects. Our results indicate a sister-group relationship between a clade Palaeoptera (dragonflies + mayflies) and the megadiverse monophyletic lineage Neoptera. We show that despite considerable structural similarity between the odonate and neopteran mandible, the muscle equipment in dragonflies is more plesiomorphic with respect to Dicondylia than previously known. Odonata and Ephemeroptera also share presumably derived features of the antenna, maxilla, and labial musculature. Parsimony analyses of the head data unambiguously support a clade Palaeoptera. � The Willi Hennig Society 2012.

Background The phylogenetic relationships of Odonata (dragonflies and damselflies) and Ephemeroptera (mayflies) remain unresolved. Different researchers have supported one of three hypotheses (Palaeoptera, Chiastomyaria or Metapterygota) based on data from different morphological characters and molecular markers, sometimes even re-assessing the same transcriptomes or mitochondrial genomes. The appropriate choice of outgroups and more taxon sampling is thought to eliminate artificial phylogenetic relationships and obtain an accurate phylogeny. Hence, in the current study, we sequenced 28 mt genomes from Ephemeroptera, Odonata and Plecoptera to further investigate phylogenetic relationships, the probability of each of the three hypotheses, and to examine mt gene arrangements in these species. We selected three different combinations of outgroups to analyze how outgroup choice affected the phylogenetic relationships of Odonata and Ephemeroptera. Methods Mitochondrial genomes from 28 species of mayflies, dragonflies, damselflies and stoneflies were sequenced. We used Bayesian inference (BI) and Maximum likelihood (ML) analyses for each dataset to reconstruct an accurate phylogeny of these winged insect orders. The effect of outgroup choice was assessed by separate analyses using three outgroups combinations: (a) four bristletails and three silverfish as outgroups, (b) five bristletails and three silverfish as outgroups, or (c) five diplurans as outgroups. Results Among these sequenced mitogenomes we found the gene arrangement IMQM in Heptageniidae (Ephemeroptera), and an inverted and translocated tRNA-Ile between the 12S RNA gene and the control region in Ephemerellidae (Ephemeroptera). The IMQM gene arrangement in Heptageniidae (Ephemeroptera) can be explained via the tandem-duplication and random loss model, and the transposition and inversion of tRNA-Ile genes in Ephemerellidae can be explained through the recombination and tandem duplication-random loss (TDRL) model. Our phylogenetic analysis strongly supported the Chiastomyaria hypothesis in three different outgroup combinations in BI analyses. The results also show that suitable outgroups are very important to determining phylogenetic relationships in the rapid evolution of insects especially among Ephemeroptera and Odonata. The mt genome is a suitable marker to investigate the phylogeny of inter-order and inter-family relationships of insects but outgroup choice is very important for deriving these relationships among winged insects. Hence, we must carefully choose the correct outgroup in order to discuss the relationships of Ephemeroptera and Odonata.

International audience; A new dictyoneurid insect, Dictyoneura goujonorum n. sp. from the Latest Ghzelian-Asselian basin of Graissessac (Hérault, France) is described in details. It is represented by a wellpreserved specimen with wings of 32-35 mm long and 13-14 mm wide and other peculiar diagnostic characters such a MP with four branches and a CuP with three branches. As all the other Dictyoneura species are known from the Namurian and/or the Wesphalian, Dictyoneura goujonorum n. sp. is the youngest representative of the genus. It is also the first record of the order Palaeodictyoptera from the Graissessac basin. The Carboniferous-Permian palaeodictyopterans are well-known to have lived in rather humid swamp forests. The global warming and drying of the climate during the Permian and/or the rise of potential predators may be responsible of their extinction.

International audience; Anhuihymen medianelongata Huang and Nel, gen. nov. et sp. nov., first accurate Chinese Protohymenidae, is described from the Middle Permian Yinping Formation at Chaohu, Anhui Province, Southern China. This region was under a warm and humid climate and separated from the drier Laurussia by the paleo-Thetys ocean during the Middle Permian. This discovery shows that this group was probably very widely distributed during the Permian, and adapted to very different climates and biotas. It also confirms that our current knowledge on the Permian fossil insects is very fragmentary.

A new species of ‘Megasecoptera-like’ insect, Sinodiapha ramosa gen. and sp. nov., is described based on two specimens from the Xiaheyan locality (early Pennsylvanian) of China, one of which displa...

The structure of insect wing articulation is considered as reliable source of high level characters for phylogenetic analyses. However, the correct identification of homologous structures among the main groups of Pterygota is a hotly debated issue. Therefore, the reconstruction of the wing bases in Paleozoic extinct relatives is of great interest, but at the same time it should be treated with extreme caution due to distortions caused by taphonomic effects. The present study is focused on the wing base in Dunbaria (Spilapteridae). The articulation in Dunbaria quinquefasciata is mainly formed by a prominent upright axillary plate while the humeral plate is markedly reduced. Due to unique preservation of surface relief of the axillary plate, its composition shows a detailed pattern of three fused axillary sclerites and presumable position of the sclerite 3Ax. The obtained structures were compared among Spilapteridae and to other palaeodictyopterans Ostrava nigra (Homoiopteridae) and Namuroningxia elegans (Namuroningxiidae). The comparative study uncovered two patterns of 3Ax in Dunbaria and Namuroningxia, which correspond to their different suprafamilial classification. In contrast to previous studies these new results reveal the homologous structural elements in the wing base between Paleozoic Palaeodictyoptera and their extant relatives of Ephemeroptera, Odonata and Neoptera.

The impacts of the modern, agrochemicals based agriculture that threatens the overall systems sustainability, need to be monitored and evaluated. Seeking for agroecosystems monitors, the present article focus in the occurrence and abundance of aquatic macroinvertebrates, that have been frequently used as bioindicators of water quality due to their relationship with land use. Some of these organisms are on the top of the food chain, where bioaccumulation and biomagnification processes can be observed, and they can turn into secondary pollution sources of systems and terrestrial organisms as well. Odonate nymphs, which belong to the functional group of predators, were selected for this study. A methodology to determine 73 pesticide residues in odonate nymphs by LC-MS/MS and GC-MS/MS was developed. A QuEChERS sample preparation strategy was adapted. As it is complex to obtain samples especially in disturbed ecosystems, the method was minimized to a sample size of 200mg of fresh nymphs. The method was validated and good recoveries (71-120%) with RSDs below 20% for the majority of the studied pesticides at least at two of the assayed levels 1, 10 and 50µgkg-1 were obtained. For 32 analytes the limit of quantitation was 1µgkg-1 and 10µgkg-1 for the others. The lineal range was observed between 1-100µgkg-1 in matrix-matched and solvent calibration curves for most of the assessed pesticides. LC-MS/MS matrix effects were evaluated, 40% of the analytes presented low or no signal suppression. Only flufenoxuron presented high matrix effects. The obtained methodology is adequate for pesticide multiresidue analysis in aquatic macroinvertebrates (odonates) aiming to contribute to the ecological state evaluation of freshwater ecosystems.

Insects are the most diverse animal group, with 1 million species described. This success is due in part to their long evolutionary history, as they emerged about 475 Mya, as well as to their different morphophysiological innovations. A key innovation was the emergence of wings about 410 Mya. Another one was metamorphosis, which occurred practically simultaneously to the emergence of wings. Wingless (apterygote) insects are ametabolan; that is, they do not change during the postembryonic development. In contrast, winged (pterygote) insects undertake metamorphosis. In the early-branching pterygotes (Palaeoptera, Polyneoptera, and Paraneoptera superorders), the developmental mode is categorized as hemimetaboly and comprises three stages: the embryo, the juvenile instars or nymphs, and the adult, which is similar to the nymphs. In the superorder Endopterygota, which emerged some 370 Mya, the developmental mode is categorized as holometaboly and comprises four stages: the embryo, the juvenile instars or larvae, the pupa, and the adult, which is different from the larvae. Thus the pupa bridges the gap between the larvae and the adult. The embryogenesis of all insects includes the essential steps of syncytial cleavage, germ band and blastoderm formation, differentiation of the ectoderm, mesoderm, and endoderm, and organogenesis. However, embryo development of ametabolan, hemimetabolan, and holometabolan species differ each other in significant details, such the number of cuticles deposited, the type of germ band, the complexity of blastokinesis, and peculiarities of the organogenesis.

The series of two fossil species belonging to the order Palaeodictyoptera from the Late Carboniferous of Kuznetsk Basin in Russia were re-examined. The two species as Tchirkovaea guttata and Paimbia fenestrata were investigated with emphasis on the wing growth and development in comparison with the structure of developing wings in recent mayflies. This fossil material of T. guttata and P. fenestrata was long considered by previous authors as undisputed evidence for a unique type of wing development in the Palaeozoic insects. The idea was that the larvae of these insects possessed the wings, which became articulated and fully movable already earlier during the postembryonic development and that these gradually growing wings changed their position from longitudinal to perpendicular to the body axis. Moreover, the development was supposed to include two or more subimaginal instars, implying that the fully winged instars moulted several times during postembryonic development. After detailed study of the available fossils and subsequent comparison of the fossil evidence with the development of wings in the recent mayfly Cloeon dipterum it was discovered, that the alleged series of immature, subimaginal and imaginal wings of T. guttata and P. fenestrata do not provide clear evidence that would support...

Phylogenetic relationships of basal insects remain a matter of discussion. In particular, the relationships among Ephemeroptera, Odonata and Neoptera are the focus of debate. In this study, we used a next-generation sequencing approach to reconstruct new mitochondrial genomes (mitogenomes) from 18 species of basal insects, including six representatives of Ephemeroptera and 11 of Odonata, plus one species belonging to Zygentoma. We then compared the structures of the newly sequenced mitogenomes. A tRNA gene cluster of IMQM was found in three ephemeropteran species, which may serve as a potential synapomorphy for the family Heptageniidae. Combined with published insect mitogenome sequences, we constructed a data matrix with all 37 mitochondrial genes of 85 taxa, which had a sampling concentrating on the palaeopteran lineages. Phylogenetic analyses were performed based on various data coding schemes, using maximum likelihood and Bayesian inferences under different models of sequence evolution. Our results generally recovered Zygentoma as a monophyletic group, which formed a sister group to Pterygota. This confirmed the relatively primitive position of Zygentoma to Ephemeroptera, Odonata and Neoptera. Analyses using site-heterogeneous CAT-GTR model strongly supported the Palaeoptera clade, with the monophyletic Ephemeroptera being sister to the monophyletic Odonata. In addition, a sister group relationship between Palaeoptera and Neoptera was supported by the current mitogenomic data.

Topographic anatomy of ascending (AN) and descending (DN) neurons of the supraesophageal and thoracic ganglia in the nervous system of winged insects (Pterygota), representatives of the infraclasses Palaeoptera (Odonata, Aeschna grandis, dragonfly) and Neoptera (Blattoptera, Periplaneta americana, cockroach), was studied. These insects differ in ecological niches, lifestyles, sets of behavioral complexes, levels of locomotor system development, evolutionary age and systematic position. Cell bodies and processes of ANs and DNs were stained with nickel chloride (NiCl2), and their topography was studied on total preparations of the supraesophageal and thoracic ganglia. Unlike cockroaches, the dragonfly protocerebrum was found to contain DNs sending their processes to ocelli. Dragonfly DN processes exhibit a specific branching pattern in thoracic ganglia, with collaterals coming off both ipsi- and contralaterally. In cockroaches, collaterals of DN processes come off ipsilaterally. The AN cell bodies in dragonfly meso- and metathoracic ganglia lie both ipsi- and contralaterally relative to the ascending process, whereas in cockroaches most of the AN cell bodies in the same ganglia are located contralaterally. Substantial differences in the distrubution of DNs and ANs in insects with different manners of locomotion appear to reflect different degrees of control the supraesophageal ganglion exerts over the activity of segmental centers. This does not seem to be related to the evolutionary age of insects or their systematic position. Probably, different degrees of control over locomotion depend on the way of food acquisition: catching prey in the air in “paleopterous” dragonflies versus maneuverable walking or running over a solid substrate in “neopterous” cockroaches.

We report the discovery of a new Calvertiellidae from the Xiaheyan locality (Namurian, early Late Carboniferous; Tupo Formation; China), namely Xiaheyanella orta gen. et sp. n. Besides representing both the most ancient and the most oriental occurrences for the family, the new species exhibits a derived wing venation pattern, especially if compared to the putative palaeodictyopteran cousins of the family. This discovery shows that, by the early Late Carboniferous, many insect lineages of moderate importance (i.e., considered at the familial level or below) already had a widespread distribution, and that derived conditions already accumulated. This concurs with the view that insects had already experienced a long evolutionary history by that time, remaining to be documented.

Can you name the five most significant evolutionary changes that made beetles the most successful and diversified of all insects? Hint : check Fig. 1 for the five modifications marked on the evolutionary tree of insect orders. Fig. 1. The most strongly supported clades of the insect orders show dramatic changes in the number of species (estimates based on Gullan and Cranston 2005), suggesting that the changes at the numbered nodes represent major improvements in fitness. Odonata and Ephemeroptera (together known as Palaeoptera) are 3 times as speciose as the more primitive, wingless orders; orthopteroid orders (Pliconeoptera) together are 4 times as speciose as Palaeoptera; hemipteroid orders (here named Clavoptera) are 4 times as speciose as Pliconeoptera; neuropteroid orders (except Coleoptera) are 6 times as speciose as Clavoptera, and Coleoptera alone are almost as speciose as all the other neuropteroid orders put together, and some taxonomists claim that there are more than 10 times as many beetles as other neuropteroids. For morphological and anatomical changes at the numbered nodes, see text. Photograph by Nicholas Aflitto. The first change, of course, is the evolution of wings (node 1 in Fig. 1) that created the paleopterous orders, represented in the modern fauna by Ephemeroptera and Odonata, and the second (node 2) was the ability of Neoptera to fold those wings over the back, preventing them from being damaged when evading predators. The majority of Coleoptera have taken this process one step farther: they can fold their wings in half (node 5) and hide them under the …

The phylogenetic relationships of the winged insect lineages – mayflies (Ephemeroptera), damselflies and dragonflies (Odonata), and all other winged insects (Neoptera) – are still controversial with three hypotheses supported by different datasets: Palaeoptera, Metapterygota and Chiastomyaria. Here, we reanalyze available phylogenomic data with a focus on detecting confounding and alternative signal. In this context, we provide a framework to quantitatively evaluate and assess incongruent molecular phylogenetic signal inherent in phylogenomic datasets. Despite overall support for the Palaeoptera hypothesis, we also found considerable signal for Chiastomyaria, which is not easily detectable by standardized tree inference approaches. Analyses of the accumulation of signal across gene partitions showed that signal accumulates gradually. However, even in case signal only slightly supported one over the other hypothesis, topologies inferred from large datasets switch from statistically strongly supported Palaeoptera to strongly supported Chiastomyaria. From a morphological point of view, Palaeoptera currently appears to be the best-supported hypothesis; however, recent analyses were restricted to head characters. Phylogenetic approaches covering all organ systems including analyses of potential functional or developmental convergence are still pending so that the Palaeoptera problem has to be considered an open question in insect systematics.

Being implied in flight, mimetism, communication, and protection, the insect wings were crucial organs for the mega diversification of this clade. Despite several attempts, the problem of wing evolution remains unresolved because the basal parts of the veins essential for vein identification are hidden in the basivenal sclerites. The homologies between wing characters thus cannot be accurately verified, while they are of primary importance to solve long-standing problems, such as the monophyly of the Palaeoptera, viz. Odonatoptera, Panephemeroptera, and Palaeozoic Palaeodictyopterida mainly known by their wings. Hitherto the tools to homologize venation were suffering several cases of exceptions, rendering them unreliable. Here we reconstruct the odonatopteran venation using fossils and a new 3D imaging tool, resulting congruent with the concept of Riek and Kukalová-Peck, with important novelties, viz. median anterior vein fused to radius and radius posterior nearly as convex as radius anterior (putative synapomorphies of Odonatoptera); subcostal anterior (ScA) fused to costal vein and most basal primary antenodal crossvein being a modified posterior branch of ScA (putative synapomorphies of Palaeoptera). These findings may reveal critical for future analyses of the relationships between fossil and extant Palaeoptera, helping to solve the evolutionary history of the insects as a whole.

The phylogenetic relationships of the winged insect lineages - mayflies (Ephemeroptera), damselflies and dragonflies (Odonata), and all other winged insects (Neoptera) - are still controversial with three hypotheses supported by different datasets: Palaeoptera, Metapterygota and Chiastomyaria. Here, we reanalyze available phylogenomic data with a focus on detecting confounding and alternative signal. In this context, we provide a framework to quantitatively evaluate and assess incongruent molecular phylogenetic signal inherent in phylogenomic datasets. Despite overall support for the Palaeoptera hypothesis, we also found considerable signal for Chiastomyaria, which is not easily detectable by standardized tree inference approaches. Analyses of the accumulation of signal across gene partitions showed that signal accumulates gradually. However, even in case signal only slightly supported one over the other hypothesis, topologies inferred from large datasets switch from statistically strongly supported Palaeoptera to strongly supported Chiastomyaria. From a morphological point of view, Palaeoptera currently appears to be the best-supported hypothesis; however, recent analyses were restricted to head characters. Phylogenetic approaches covering all organ systems including analyses of potential functional or developmental convergence are still pending so that the Palaeoptera problem has to be considered an open question in insect systematics.

Phylogenetic relationships among the basal orders of winged insects remain unclear, in particular the relationship of the Ephemeroptera (mayflies) and the Odonata (dragonflies and damselflies) with the Neoptera. Insect evolution is thought to have followed rapid divergence in the distant past and phylogenetic reconstruction may therefore be susceptible to problems of taxon sampling, choice of outgroup, marker selection, and tree reconstruction method. Here we newly sequenced three mitochondrial genomes representing the two most diverse families of the Ephemeroptera, one of which is a basal lineage of the order. We then used an additional 90 insect mitochondrial genomes to reconstruct their phylogeny using Bayesian and maximum likelihood approaches. Bayesian analysis supported a basal Odonata hypothesis, with Ephemeroptera as sister group to the remaining insects. This was only supported when using an optimized data matrix from which rogue taxa and terminals affected by long-branch attraction were removed. None of our analyses supported a basal Ephemeroptera hypothesis or Ephemeroptera + Odonata as monophyletic clade sister to other insects (i.e., the Palaeoptera hypothesis). Our newly sequenced mitochondrial genomes ofBaetis rutilocylindratus,Cloeon dipterum, andHabrophlebiodes zijinensishad a complete set of protein coding genes and a conserved orientation except for two inverted tRNAs inH. zijinensis.Increased mayfly sampling, removal of problematic taxa, and a Bayesian phylogenetic framework were needed to infer phylogenetic relationships within the three ancient insect lineages of Odonata, Ephemeroptera, and Neoptera. Pruning of rogue taxa improved the number of supported nodes in all phylogenetic trees. Our results add to previous evidence for the Odonata hypothesis and indicate that the phylogenetic resolution of the basal insects can be resolved with more data and sampling effort.

In this paper we record a likely instance of ovo-viviparity in a chlorocyphid damselfly from south-western China. If confirmed, this will be the first record of live birthing in the Odonata: indeed in any member of the Palaeoptera. The widespread Asian damselfly Heliocypha perforata (Percheron, 1835) is proposed to be, at least facultatively, viviparous. A female was observed and filmed appearing to deposit pro-larvae directly onto the exposed surface of a half-submerged branch in a small stream in Xishuangbanna Autonomous Dai Prefecture, Yunnan, China. The species is known to deposit eggs in bark crevices close to water but no previous case of actual live births is known.

Palaeodictyopterida is remarkable insect superorder, which formed a significant part of the diversity of upper Palaeozoic insects, but disappeared by the end of the Permian. The main synapomorphy of the superorder is the piercing-sucking mouthparts in the form of a rostrum consisting of five styles. This rostrum was probably used to pierce on plant tissue and for the juice sucking. The same type of mouthparts shared by adults was present also in larvae of Palaeodictyopterida. The external copulatory organs of the superorder members was also showed some morphological interests. The male genitalia consist of a pair of gonostyli and two penial lobes, similarly to the genitalia of recent Ephemeroptera. The female genitalia of Palaeodictyopterida are developed in a form of the ovipositor that can be compared with the endophytic ovipositor of some recent Odonata. This morphological features support placement of Palaeodictyopterida as sister group of Odonatoptera + Panephemeroptera. The main aim of the work was to describe new representatives of the order Megasecoptera, the second largest group of Palaeodictyopterida. Wing venation of Megasecoptera exhibits a reduction of the longitudinal and transverse veins in comparison with the order Palaeodictyoptera. Other body structures were examined mainly in the...

The order in which the 3 groups of winged insects (the Pterygota) diverged from their common ancestor has important implications for understanding the origin of insect flight. But despite this importance, the split between the Odonata (dragonflies and damselflies), Ephemeroptera (mayflies), and Neoptera (the other winged orders) remains very much unresolved. Indeed, previous studies have obtained strong apparent support for each of the 3 possible branching patterns. Here, we present a systematic reinvestigation of the basal pterygote split. Our results suggest that outgroup choice and limited taxon sampling have been major sources of systematic error, even for data sets with a large number of characters (e.g., in phylogenomic data sets). In particular, a data set of 113 taxa provides consistent support for the Palaeoptera hypothesis (the grouping of Odonata with Ephemeroptera), whereas results from data sets with fewer taxa give inconsistent results and are highly sensitive to minor changes in data and methods. We also focus on recent methods that exploit temporal information using fossil calibrations, combined with additional assumptions about the evolutionary process, and so reduce the influence of outgroup choice. These methods are shown to provide more consistent results, for example, supporting Palaeoptera, even for data sets that previously supported other hypotheses. Together, these results have implications for understanding insect origins and for resolving other problematic splits in the tree of life. (Bayesian phylogenetics; BEAST; Chiastomyaria; Metapterygota; Pterygota.)

The relationships of the 3 major clades of winged insects—Ephemeroptera, Odonata, and Neoptera—are still unclear. Many morphologists favor a clade Metapterygota (Odonata+Neoptera), but Chiastomyaria (Ephemeroptera+ Neoptera) or Palaeoptera (Ephemeroptera+Odonata) has also been supported in some older and more recent studies. A possible explanation for the difficulties in resolving these relationships is concerted convergence—the convergent evolution of entire character complexes under the same or similar selective pressures. In this study, we analyze possible instances of this phenomenon in the context of head structures of Ephemeroptera, Odonata, and Neoptera. We apply a recently introduced formal approach to detect the occurrence of concerted convergence. We found that characters of the tentorium and mandibles in particular, but also some other head structures, have apparently not evolved independently, and thus can cause artifacts in tree reconstruction. Our subsequent analyses, which exclude character sets that may be affected by concerted convergence, corroborate the Palaeoptera concept. We show that the analysis of homoplasy and its influence on tree inference can be formally improved with important consequences for the identification of incompatibilities between data sets. Our results suggest that modified weighting (or exclusion of characters) in cases of formally identified correlated cliques of characters may improve morphology-based tree reconstruction. (Character clique; convergent evolution; Chiastomyaria; Ephemeroptera; homoplasy; Metapterygota; morphology; mouthparts; Odonata; phylogeny.)

This is the first reported primary sequence of a bioactive peptide isolated from three Ephemeroptera families. Peptides of the adipokinetic hormone (AKH) family from the corpora cardiaca of nymphs of Afronurus spp. (Family: Heptageniidae), Siphlonurus lacustris (Family: Siphlonuridae) and Ephemera danica (Family: Ephemeridae) were investigated functionally in homologous (hypertrehalosaemic activity demonstrated in E. danica nymphs) and heterologous (active in cockroach and locust) bioassays, and structurally by liquid-chromatography coupled with ion trap electrospray ionisation mass spectrometry. All species investigated synthesise the octapeptide code-named Anaim-AKH (pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp amide). Confirmation of this peptide being present in corpora cardiaca of E. danica nymphs was obtained via reverse phase-high pressure liquid chromatography. Phylogenetically, the presence of only one AKH peptide may constitute a basal condition; all other lower insect orders, e.g. Odonata, Blattodea, Orthoptera, amongst others, have more than one AKH analogue. We propose that Anaim-AKH is the ancestral peptide which may support the Palaeoptera hypothesis that mayflies (Ephemeroptera) and dragonflies (Odonata) form the Palaeoptera clade, the sister group of Neoptera. The structural data cannot, however, shed any light on the phylogenetic scenarios within Ephemeroptera itself. Finally, this study demonstrates the successful use of larvae as an alternative biological source to study neuropeptides in ephemeral, elusive or difficult to obtain adult insects.

Taphonomic conditions of insects from the Late Carboniferous (Pennsylvanian) Konservat-Lagerstatte Hagen-Vorhalle (western Germany) are remarkably unique but have not been the focus of detailed work thus far. Their particular preservation is conspicuous and furthermore shows significant differences between “Palaeoptera” and Neoptera. The first are almost always completely preserved while the latter invariably lack an abdomen. Furthermore all Neoptera bear tiny bivalve prodissoconchs (~ 0.8–1.2 mm) or few dissoconchs (~ 1.3–1.4 mm) exclusively on the dorsal wing membrane. Taking into account geological, sedimentological, paleontological and paleo-oceanological data a novel taphonomic model is presented here. After a short period of drifting along the water/air contact layer “Palaeoptera” sank directly to the bottom whereas the soft-tissued abdomens of Neoptera began to decay under these oxic conditions. After loosing their abdomen the corpses sank to a pycnocline in a strongly stratified water body where a second period of drifting took place. At this stage the wings were settled by attaching bivalve larvae derived from a river. When the weight of the shells increased the insect/bivalve association broke through the pycnocline and sank to the bottom where they were finally embedded and fossilized.