A new surface gliding species of Chironomidae: An independent invasion of marine environments and its evolutionary implications

Insects have invaded marine habitats only rarely and secondarily. Recently, we discovered a flightless dipteran species skating rapidly on the surface of seawater ponds at the Pacific coast of eastern China. Morphological analyses initially suggested an isolated position of the non‐biting midge, suggesting the erection of a new genus within Chironomini (Diptera: Chironomidae). However, an analysis of molecular data revealed that the marine species is in fact nested within the species‐rich genus Dicrotendipes. The apparent conflict between molecular and morphological data can be easily explained. It is likely that the new species has evolved a series of autapomorphic adaptations. These traits clearly distinguish the taxon from other species of the genus but do not justify the erection of a new supraspecific taxon, which would render Dicrotendipes paraphyletic. The switch to marine environments was likely a trigger for various morphological modifications resulting from increased selective pressure. Molecular data suggest that the potential speciation event occurred around 19–29 Ma, linked with a migration from freshwater to seawater ponds along the Pacific Ocean. Considering the results of our analysis, we place the flightless marine skater in the genus Dicrotendipes. All life stages of Dicrotendipes sinicus Qi & Lin sp. n. are described and illustrated, associated with larvae obtained by rearing or confirmed through association with DNA barcodes. The biology and ecology of the species are outlined based on collection data and in situ observations. Evolutionary patterns linked with repeated invasions of marine habitats are discussed

Have female twisted-wing parasites (Insecta: Strepsiptera) evolved tolerance traits as response to traumatic penetration?

Traumatic insemination describes an unusual form of mating during which a male penetrates the body wall of its female partner to inject sperm. Females unable to prevent traumatic insemination have been predicted to develop either traits of tolerance or of resistance, both reducing the fitness costs associated with the male-inflicted injury. The evolution of tolerance traits has previously been suggested for the bed bug. Here we present data suggesting that tolerance traits also evolved in females of the twisted-wing parasite species $\textit{Stylops ovinae}$ and $\textit{Xenos vesparum}$. Using micro-indentation experiments and confocal laser scanning microscopy, we found that females of both investigated species possess a uniform resilin-rich integument that is notably thicker at penetration sites than at control sites. As the thickened cuticle does not seem to hamper penetration by males, we hypothesise that thickening of the cuticle resulted in reduced penetration damage and loss of haemolymph and in improved wound sealing. To evaluate the evolutionary relevance of the $\textit{Stylops}$-specific paragenital organ and penis shape variation in the context of inter- and intraspecific competition, we conducted attraction and interspecific mating experiments, as well as a geometric-morphometric analysis of $\textit{S ovinae}$ and $\textit{X vesparum}$ penises. We found that $\textit{S ovinae}$ females indeed attract sympatrically distributed congeneric males. However, only conspecific males were able to mate. In contrast, we did not observe any heterospecific male attraction by $\textit{Xenos}$ females. We therefore hypothesise that the paragenital organ in the genus $\textit{Stylops}$ represents a prezygotic mating barrier that prevents heterospecific matings

Evidence for the evolution of eusociality in stem ants and a systematic revision of †Gerontoformica (Hymenoptera: Formicidae)

It is generally assumed that Cretaceous stem ants were obligately eusocial, because of the presence of wingless adult females, yet the available evidence is ambiguous. Here, we report the syninclusion of a pupa and adult of a stem ant species from Mid-Cretaceous amber. As brood are immobile, the pupa was likely to have been transported by an adult. Therefore, the fossil substantiates the hypothesis that wingless females were cooperators, thus these were true ‘workers’. Re-examination of all described Cretaceous ant species reveals that winged–wingless diphenism – hence a variable dispersal capacity – may have been ancestral to the total clade of the ants, and that highly specialized worker-specific phenotypes evolved in parallel between the stem and crown groups. The soft-tissue preservation of the fossil is exceptional, demonstrating the possibility of analysing the development of the internal anatomy in stem ants. Based on the highest-resolution µ-CT scans of stem ants to date, we describe †Gerontoformica sternorhabda sp. nov., redescribe †G. gracilis, redefine the species group classification of †Gerontoformica, and provide a key to the species of the genus. Our work clarifies the species boundaries of †Gerontoformica and renders fossils relevant to the discussion of eusocial evolution in a way that has heretofore been intractable.journal articl

The evolution of head structures in lower Diptera

The head of adult dipterans is mainly characterized by modifications and more or less far reaching reductions of the mouthparts (e.g., mandibles, maxillae), linked with the specialization on liquid food and the reduced necessity to process substrates mechanically. In contrast, the compound eyes and the antennae, sense organs used for orientation and for finding a suitable mating partner and oviposition site, are well developed. Some evolutionary novelties are specific adaptations to feeding on less liquefied substrates, such as labellae with furrows or pseudotracheae on their surface, and the strongly developed pre- and postcerebral pumping apparatuses. In some dipteran groups specialized on blood the mandibles are still present as piercing stylets. They are completely reduced in the vast majority of families. Within the group far-reaching modifications of the antennae take place, with a strongly reduced number of segments and a specific configuration in Brachycera. The feeding habits and mouthparts of dipteran larvae are much more diverse than in the adults. The larval head is prognathous and fully exposed in the dipteran groundplan and most groups of lower Diptera. In Tipuloidea and Brachycera the head is partly or largely retracted and the sclerotized elements of the external head capsule are partly or fully reduced. The head of Cyclorrhapha is largely reduced. A complex and unique feature of this group is the cephaloskeleton. The movability of the larvae is limited due to the lack of thoracic legs. This can be partly compensated by the mouthparts, which are involved in locomotion in different groups. The mouth hooks associated with the cyclorrhaphan cephaloskeleton provide anchorage in the substrate

Hydrophiloidea Latreille, 1802

Since the first of three Coleoptera volumes of the Hand-book of Zoology series was published in 2005, the progress in the investigation of the most species-rich insect order has been remarkable. The exploration of the biodiversity of this extremely successful group of organisms has been dynamic, with valuable contributions made by individual naturalists, but also by organized research teams conducting large-scale biodiversity expeditions in different parts of the world. These efforts have yielded a remarkable increase in species numbers in different groups, as for instance in Hydrophiloidea from ca. 2,800 in 2005 (1stedition) to 3,335 in 2015 (1?12), or in Staphylinidae from 47,744 in 2005 to 55,224 in 2015 (1?14.7), the later of which is also related to advances in classification. Moreover, a considerable number of new genera were described as well as two new families of Adephaga, which were not included in the 1stedition of Volume 1 (included in Volume 2 of 2010). The biodiversity explorations were accompanied by intensive taxonomic work conducted not only by professional researchers but also highly competent amateurs. Even though taxonomic research may not be greatly appreciated in parts of the scientific community, or governments, it is essential for the understanding of a highly complex and immensely diverse group like Coleoptera and generally for the development of stable classifications. An updated classification for the all Coleoptera is presented in Chapters 1?2. Important changes adopted here are the placement of Scirtoidea at the base of Polyphaga, and a new concept of Hydrophiloidea with subfamilies ranked as families (Chapters 1?12).With remarkable technical innovations in insect anatomy in the last decade, the study of the morphology of Coleoptera has also intensified. Recently, as part of the Beetle Tree of Life project (funded by the United States National Science Foundation), an impressive morphological contribution was made by John Lawrence, Adam Ślipiński (CSIRO), and coworkers. This team of experts compiled, documented, and analyzed a comprehensive set of 516 characters representing 314 families and subfamilies of Coleoptera plus outgroups. New and detailed morphological data are available for species of many groups (e.g. cephalic and thoracic morphology of Archostemata, head morphology of Lepiceridae, Dascillidae, and Glaresidae, genital morphology of Ommatidae, Chapters 1?5.4), and larvae of several groups were described for the 1sttime (Lepiceridae, 1?6.1, Meruidae, 1?7.8) or treated in detail morphologically, including complete 3D.reconstructions of external and internal structures (e.g. 1stinstar larvae of TenomergaNeboiss [Cupedidae], 1?5.2). The remarkable development of molecular systematics in the last decade had also a strong impact on beetle phylogenetics and evolutionary biology. A completely new chapter on molecular systematics is presented in this volume (1?3). One major achievement was the unambiguous systematic placement of Coleoptera as sistergroup to the highly specialized ectoparasitic Strepsiptera, both combined as Coleopterida, which in turn form the sistergroup to a clade   containing the three neuropteroid orders. Another breakthrough was the identification of the scirtoid families and Derodontidae as basal lineages of the megadiverse Polyphaga.The composition of the authors for this revised Volume 1 has changed slightly. Chuck Bellamy, regrettably passed away prior to the formulation of this new edition, and Buprestidae (1?18) were revised with the assistance of Mark Volkovitsch (Institute of Zoology, Russian Academy of Sciences, St. Peterburg). Some authors were unavailable or were substituted by authors more recently active in the taxonomy of particular families. Duane McKenna (University of Memphis) is co-author of Systematic position and early evolution (1?1) and new author of Molecular systematics of Coleoptera; (1?3), Lars Hendrich (Zoologische Staatssammlung München) as new co-author of Dytiscidae (1?7.6), Pawel Jaloszynski (Museum of Natural History, University of Wrocław) and as new author of Scydmaeninae; (1?14.5), and Crystal Maier (Field Museum of Natural History, Chicago) as leading author of Byrrhidae (1?19.1).Not only are great strides being made to document beetle diversity and morphology, the investigation of beetle phylogeny is also presently progressing with great momentum. The phylogeny of the entire Coleoptera was addressed in the BTOL project and is presently investigated based on transcriptomes in a subproject of the 1KITE consortium (www.1KITE.org/, funded by Beijing Genomics Institute). This and other ongoing molecular investigations underway by teams of researchers combined with new morphological findings and an intensified exploration of rich fossil material, will likely lead to a deeper understanding of beetle evolution and new classifications in the near future. The updated information compiled in this volume may facilitate and inspire ongoing research efforts, and new phylogenetic and evolutionary insights may eventually lead to new contributions in the Handbook of Zoology series.Fil: Archangelsky, Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; ArgentinaFil: Beutel, Rolf Georg. Universitat Jena; AlemaniaFil: Komarek, Albrecht. Natural History Museum Vienna; Alemani

On the head morphology of Tetraphalerus, the phylogeny of Archostemata and the basal branching events in Coleoptera

Internal and external features of Tetraphalerus bruchi were studied using X-ray microtomography (mu-CT) and other techniques, and head structures were described in detail. mu-Ct is highly efficient for the assessment of anatomical data. A data matrix with 90 morphological characters of recent and fossil beetles was analyzed with different approaches (parsimony, Bayesian analysis). The results of the parsimony analysis resulted in the following branching pattern: (dagger Tshekardocoleidae + (dagger Permocupedidae, dagger Rhombocoleidae + (dagger Triadocupedidae + ((Adephaga + (Myxophaga + Polyphaga))) + Archostemata s.str. [including Jurodidae]))). Sikhotealinia is placed as sister group of dagger Jurodes (Jurodidae), and Jurodidae as sister group of the remaining Archostemata (Bayesian analysis) or of a clade comprising Micromalthidae, Crowsoniellidae, dagger Ademosynidae, dagger Schizophoridae and dagger Catiniidae. The monophyly of Ommatidae and Cupedidae is well supported and Priacma is placed as the sister group of all other Cupedidae. Important events in the early evolution of Coleoptera are the shortening of the elytra and the transformation of the elytral venation (Coleoptera excluding dagger Tshekardocoleidae), the formation of a closed subelytral space (Coleoptera excluding dagger Tshekardocoleidae and dagger Permocupedidae), the reduction of two apical antennomeres, and the loss of the broad prothoracic postcoxal bridge (Coleoptera excluding dagger Tshekardocoleidae, dagger Permocupedidae and dagger Rhombocoleidae). Plesiomorphic features preserved in extant Archostemata are the tuberculate cuticle, the elytral pattern with parallel longitudinal ribs and window punctures, a mesoventrite with a transverse ridge, triangular mesocoxae with a distinct meron, and the exposed metatrochantin. The fossils included in the analyses do not only contribute to the reconstruction of character evolution but also influence the branching pattern. An understanding of the major evolutionary events in Coleoptera would not be possible without considering the rich fossil record of Permian and Mesozoic beetles. (C) The Willi Hennig Society 2007

Patterns of morphological simplification and innovation in the megadiverse Holometabola (Insecta)

We analyzed patterns of complexity and simplicity in holometabolan insects using parsimony and maximum-likelihood. By contrast with other groups of arthropods (and most other groups of animals), insects have undergone a stepwise process of structural simplification in their evolution. The megadiverse Holometabola are characterized mainly by structurally simplified larvae, which differ strongly from the adults in their morphology and usually also in their life habits. Although smaller groups such as Neuropterida have largely maintained their structural complexity in adults and immature life stages, a series of reductions occurred with the appearance and diversification of Coleopterida, Mecopterida and especially Antliophora. Parasitic Strepsiptera or fleas display conspicuous patterns of reduction in different life stages and body regions, and high degrees of simplification also occur in groups with short-lived adults. Larvae living in moist substrates display far-reaching structural simplifications and also morphological uniformity, especially in the species-rich Diptera, but also in other groups. Liquid feeding leads to correlated simplifications and innovation of adult head structures, especially of the mouthparts. Functional or anatomical dipterism leads to an optimization of the flight apparatus in most holometabolous groups, which is correlated with reductions in one of the pterothoracic segments, and coupled (e.g. by hamuli), partly reduced or transformed wings (e.g. halteres). In flightless groups, the pterothoracic skeleto-muscular apparatus is strongly simplified. In the abdomen of adult females a stepwise reduction of the lepismatoid ovipositor occurs. By contrast, the male genital apparatus often undergoes an extreme diversification. Our evaluations revealed a highly correlated complexity between larval and adult stages

Distal leg morphology, subgenual organs and host detection in Stephanidae (Insecta, Hymenoptera)

Vilhelmsen, Lars, Turrisi, Giuseppe Fabrizio, Beutel, Rolf Georg (2008): Distal leg morphology, subgenual organs and host detection in Stephanidae (Insecta, Hymenoptera). Journal of Natural History 42 (23-24): 1649-1663, DOI: 10.1080/00222930802105155, URL: http://dx.doi.org/10.1080/0022293080210515