Morphology of the elytral base sclerites

The elytral base sclerites (= sclerites located at the articular region between the forewing and thorax in Coleoptera) of selected taxa were examined and homologized. Although the elytral base sclerites are highly modified compared to the wing base sclerites of the other neopterans, they can be homologized by using the conservative wing flapping and folding lines as landmarks. A reduction of the first axillary sclerite was identified as a general trend of the elytral base sclerites, although the sclerite usually has a very important function to mediate flight power from the notum to the wing. This result indicates that the functional constraint against the basal sclerites is relaxed because of the lack of an ability to produce flight power by elytra. In contrast, the elytral folding system formed by the basal sclerites is well retained, which probably occurs because proper wing folding is a key for the shelter function of the elytra. The elytral base sclerites apparently contain more homoplasies than the serially homologous hindwing base sclerites of Coleoptera, which suggests that the structure is less useful for higher-level systematics. However, the faster evolutionary rate of the elytral base sclerites suggests there is potential for studying the lower-level phylogeny of Coleoptera.     

基于四种金龟的昆虫后翅关节骨片三维形态复杂性研究

【目的】昆虫的翅非常精巧与灵活,翅脉及翅关节的形态及功能长久以来受到众多领域科学家的广泛关注。由于历史条件的限制,昆虫翅的研究主要集中在翅脉,即使少量的有关翅关节形态的研究也主要是停留在二维形态数据分析的层面上。更重要的是,各骨片内部形态结构还未见报道。本研究的目的就是为了重建翅关节骨片内部和外部复杂的三维形态结构,全面呈现利用传统形态学方法无法获得的形态学信息,进而深入探究昆虫翅的形态与功能的关系。【方法】本文利用显微CT对鞘翅目4种金龟进行了扫描,通过计算机三维重建技术,对折叠和展开状态时后翅关节各个骨片（第1, 2和3腋片及中片）的内部和外部的三维形态进行研究,展示和分析昆虫翅关节内部与外部形态结构和空间运动的复杂性。【结果】翅关节骨片的三维重建模型及虚拟切面图展示了其复杂的外部形态,主要表现在表面曲率的不均匀变化和部分结构的互相遮挡两个方面。前者主要表现骨片表面具有突起、沟槽、弯折以及外长物等。后者指各骨片均呈现了不同程度的弯折,有的弯折还会互相接触,最终形成筒状结构,这样不可避免造成部分结构被遮挡或包裹。三维重建模型的断层图显示了翅关节骨片并非是实心的结构,而是分为两层：靠近表皮的为高度骨化的外骨骼,而靠近骨片核心则为疏松的类似海绵状结构。本文还展示了各个骨片在后翅折叠状和展开状态下的空间位置,并对所研究的4个科的翅关节骨片的三维形态进行了比较。【结论】翅关节骨片具有复杂的内部和外部形态结构。关节骨片的内部海绵结构和外层强烈骨化的双层结构,可能与其尽量减小骨片的重量和节约运动能量,同时又尽量保持骨片的刚性结构的形态适应策略有关。此类形态适应在材料学、空气动力学等领域具有重要的仿生学意义。     

Origin and evolution of insect wings and their relation to metamorphosis,as documented by the fossil record

In contemporary entomology the morphological characters of insects are not always treated according to their phylogenetic rank. Fossil evidence often gives clues for different interpretations. All primitive Paleozoic pterygote nymphs are now known to have had articulated, freely movable wings reinforced by tubular veins. This suggests that the wings of early Pterygota were engaged in flapping movements, that the immobilized, fixed, veinless wing pads of Recent nymphs have resulted from a later adaptation affecting only juveniles, and that the paranotal theory of wing origin is not valid. The wings of Paleozoic nymphs were curved backwards in Paleoptera and were flexed backwards at will in Neoptera, in both to reduce resistance during forward movement. Therefore, the fixed oblique-backwards position of wing pads in all modern nymphs is secondary and is not homologous in Paleoptera and Neoptera. Primitive Paleozoic nymphs had articulated and movable prothoracic wings which became in some modern insects transformed into prothoracic lobes and shields. The nine pairs of abdominal gillplates of Paleozoic mayfly nymphs have a venation pattern, position, and development comparable to that in thoracic wings, to which they are serially homologous. Vestigial equivalents of wings and legs were present in the abdomen of all primitive Paleoptera and primitive Neoptera. The ontogenetic development of Paleozoic nymphs was confluent, with many nymphal and subimaginal instars, and the metamorphic instar was missing. The metamorphic instar originated by the merging together of several instars of old nymphs; it occurred in most orders only after the Paleozoic, separately and in parallel in all modern major lineages (at least twice in Paleoptera, in Ephemeroptera and Odonata; separately in hemipteroid, blattoid, orthopteroid, and plecopteroid lineages of exopterygote Neoptera; and once only in Endopterygota). Endopterygota evolved from ametabolous, not from hemimetabolous, exopterygote Neoptera. The full primitive wing venation consists of six symmetrical pairs of veins; in each pair, the first branch is always convex and the second always concave; therefore costa, subcosta, radius, media, cubitus, and anal are all primitively composed of two separate branches. Each pair arises from a single veinal base formed from a sclerotized blood sinus. In the most primitive wings the circulatory system was as follows: the costa did not encircle the wing, the axillary cord was missing, and the blood pulsed in and out of each of the six primary, convex-concave vein pair systems through the six basal blood sinuses. This type of circulation is found as an archaic feature in modern mayflies. Wing corrugation first appeared in preflight wings, and hence is considered primitive for early (paleopterous) Pterygota. Somewhat leveled corrugation of the central wing veins is primitive for Neoptera. Leveled corrugation in some modern Ephemeroptera, as well as accentuated corrugation in higher Neoptera, are both derived characters. The wing tracheation of Recent Ephemeroptera is not fully homologous to that of other insects and represents a more primitive, segmental stage of tracheal system. Morphology of an ancient articular region in Palaeodictyoptera shows that the primitive pterygote wing hinge in its simplest form was straight and composed of two separate but adjoining morphological units: the tergal, formed by the tegula and axillaries; and the alar, formed by six sclerotized blood sinuses, the basivenales. The tergal sclerites were derived from the tergum as follows: the lateral part of the tergum became incised into five lobes; the prealare, suralare, median lobe, postmedian lobe and posterior notal wing process. From the tips of these lobes, five slanted tergal sclerites separated along the deep paranotal sulcus: the tegula, first axillary, second axillary, median sclerite, and third axillary. Primitively, all pteralia were arranged in two parallel series on both sides of the hinge. In Paleoptera, the series stayed more or less straight; in Neoptera, the series became V-shaped. Pteralia in Paleoptera and Neoptera have been homologized on the basis of the fossil record. A differential diagnosis between Paleoptera and Neoptera is given. Fossil evidence indicates that the major steps in evolution, which led to the origin first of Pterygota, then of Neoptera and Endopterygota, were triggered by the origin and the diversification of flight apparatus. It is believed here that all above mentioned major events in pterygote evolution occurred first in the immature stages.     

New species of the genus <Emphasis Type="Italic">Pyrausta</Emphasis> (Lepidoptera,Crambidae) from Southern Siberia and Transcaucasia

Two new species of the pyralid genus Pyrausta Schrank, 1802, P. anastasia Shodotova, sp. n. from southern Siberia and P. alexandra Shodotova, sp. n. from the Transcaucasia, are described. P. anastasia sp. n. is very similar to P. chrysitis (Butler, 1881) in coloration and the wing pattern, but differs in the darker brown fore wings, a wider pale yellow band on the hind wing, and the structure of the aedeagus. P. alexandra sp. n. is very similar to P. falcatalis (Guenée, 1854) in coloration and the wing pattern, but differs in the darker brown wings, in the number of pale yellow spots on the fore and hind wings, and in the structure of the male and female genitalia. The holotypes and paratypes of both species are deposited in the Zoological Institute, Russian Academy of Sciences (St. Petersburg).     

The morphology and terminology of the hindwing articulation and wing base of the Coleoptera, with specific reference to the Scarabaeoidea

Abstract. Characters of the hindwing articulation and wing base are important for contributing to the solution of phylogenetic and systematic problems in the Coleoptera. In the Scarabaeoidea morphological terms proposed by previous authors do not cover many structures in sufficient detail and additional terms are needed to describe and utilize all characters used in systematic considerations; these can be used for all Coleoptera.
In this paper we identify new structures, the first basal plate and the second basal plate (two subdivisions of the coleopteran wing base), name the various yokes, braces and reinforcements found on them and propose names for various projections, lobes, indentations and embayments on the axillary sclerites (first axillary, head, neck and tail; second axillary, arm and body; third axillary, prong; basalare).     

Comparative morphological assessment and phylogenetic significance of the wing base articulation in Psylloidea (Insecta,Hemiptera, Sternorrhyncha)

The wing articulation sclerites, as well as wing base environment, of phylogenetically distant Psylloidea taxa were examined by optical and electron microscopy in order to estimate the phylogenetic significance of observed morphological patterns. The basiradial bridge is strongly developed and links the fused humeral plate, basisubcostale, basiradiale and second axillary sclerite to the fused veins R + M + Cu. The proximal median plate has a vertical orientation, which may have a role in moving the wing forward and backward. The weak sclerotization posteriad of the second axillary sclerite and anteriad to the third axillary sclerite facilitates the backward movement of the wing. The horizontal hinge (= basal hinge), the vertical hinge and the torsional hinge are the most important fold- and flexion-lines for the mobility of the wing, whereas humeral folds and the anterior axillary fold-line play a minor role. The basalare presents two horns or processes that are autapomorphic traits for the superfamily Psylloidea. The monophyly of Psylloidea is also supported by the absence of the subalare, of the median notal wing process and of the anterior arm of the third axillary sclerite (lacking articulation with second axillary sclerite). Major interspecific variations are observed in tegula, first axillary sclerite and basalare shape and size. The second distal median plate is absent in Homotoma ficus (Homotomidae) and Glycaspis brimblecombei (Spondyliaspidinae), whereas it is present in Calophya schini (Calophyidae) and Psylla buxi (Psyllinae/Arytaininae); the presence of this sclerite could be a synapomorphy linking Calophyidae and the “psyllid assemblage”.     

Design and Demonstration of Insect Mimicking Foldable Artificial Wing Using Four-Bar Linkage Systems

In this work, we develop an artificial foldable wing that mimics the hind wing of a beetle （Allomyrina dichotoma）. In real flight, the beetle unfolds forewings and hind wings, and maintains the unfolded configuration unless it is exhausted. The artificial wing has to be able to maintain a fully unfolded configuration while flapping at a desirable flapping frequency. The artificial foldable hind wing developed in this work is based on two four-bar linkages which adapt the behaviors of the beetle＇s hind wing. The four-bar-linkages are designed to mimic rotational motion of the wing base and the vein folding/unfolding motion of the beetle＇s hind wing. The behavior of the artificial wings, which are installed in a flapping-wing system, is observed using a high-speed camera. The observation shows that the wing could maintain a fully unfolded configuration during flapping motion. A series of thrust measurements are also conducted to estimate the force generated by the flapping-wing system with foldable artificial wings. Although the artificial foldable wings give added burden to the flapping-wing system because of its weight, the thrust measurement results show that the flapping-wing system could still generate reasonable thrust.     

Wing kinematics during natural leaping in the mantids Mantis religiosa and Iris oratoria

High-speed flash photography was used to analyse wing movements of Mantis religiosa and Iris oratoria at the moment of take-off during natural leaping. Wing kinematics are compared with those of the similarly designed locust wing. Iris oratoria showed strong coupling between leg extensor and wing depressor muscle activity immediately prior to take-off, with a possible enhancement of jump momentum. A 'clap and peel' was observed in the hind wings of both species during the first downstroke. Supination in the mantid forewing is accomplished by a backward rotation of the whole of the main wing plate about the claval furrow. Both fore- and hind wings show pronounced ventral flexure at the lower point of stroke reversal. Camber was developed in the hind wing during the upstroke as well as the downstroke. Possible roles of the claval furrow and transverse flexion in protecting the forewing base against torsional forces generated at stroke reversal are discussed.     

Fearful symmetry? Intra-individual comparisons of asymmetry in cryptic vs. signalling colour patterns in butterflies

The signalling role of asymmetry has attracted considerable recent interest among evolutionary biologists. Although it has been studied primarily within the context of sexual selection, symmetry of signals may play a role also in inter-specific communication, such as predator–prey interactions. Both theory and experimental evidence suggest that asymmetry may impair the efficacy of visual warning signals used to deter potential predators, but increase the protective value of non-signalling, cryptic colour patterns used to decrease the risk of detection. Here we tested the prediction from this hypothesis by means of intra-individual comparisons of asymmetry in colour pattern elements in three species of moths (Arctia caja (L.), Noctua orbona (L.), Smerinthus ocellata (L.)) that possess cryptic fore wing patterns and signalling hind wing patterns. Mean asymmetries constituted 4.3% (range 2.1–7.0%) of trait size for colour pattern elements, whereas individual asymmetry levels reached as high as 26%. Asymmetry tended to be somewhat larger in cryptic patterns on fore wings than in signalling patterns on hind wings in five of six comparisons, but in only one case was the difference statistically significant. In addition, pattern elements were somewhat more asymmetric on fore wings also in Saturnia pavonia (L.), which possesses identical signalling eyespots on both fore and hind wings. The relatively low levels of asymmetry also in cryptic patterns imply either that selection does not favour increased asymmetry in cryptic patterns, or that the evolution of pronounced asymmetry is developmentally or genetically constrained.     

Numerical investigation of the aerodynamic characteristics of a hovering Coleopteran insect

The aerodynamic characteristics of the Coleopteran beetle species Epilachna quadricollis, a species with flexible hind wings and stiff elytra (fore wings), are investigated in terms of hovering flight. The flapping wing kinematics of the Coleopteran insect are modeled through experimental observations with a digital high-speed camera and curve fitting from an ideal harmonic kinematics model. This model numerically simulates flight by estimating a cross section of the wing as a two-dimensional elliptical plane. There is currently no detailed study on the role of the elytron or how the elytron-hind wing interaction affects aerodynamic performance. In the case of hovering flight, the relatively small vertical or horizontal forces generated by the elytron suggest that the elytron makes no significant contribution to aerodynamic force.     

Wing folding and the functional morphology of the wing base in Coleoptera

The wing unfolding of Pachnoda marginata was examined using digital video (50 half-fps) and high speed video sequences (1000 fps), and the skeleto-muscular apparatus of the metathorax was described. Left and right hind wing are able to promote independently of each other. The hind wings do not unfold instantly when the elytra are lifted and may also reach the flight position (and beat) while still folded. Wing promotion is exhaustible and the time needed for unfolding varies considerably. These observations strongly suggest a muscular control. Wing unfolding is probably triggered by contraction of M. pleura alaris and a resulting proximad movement of the 3rd axillary sclerite, pulling the Media posterior backwards, while the Radius anterior is held by the basalar muscle as the antagonist. Our findings are in clear contrast to the earlier assumption that the hind wings of Coleoptera either unfold or fold due to intrinsic elasticity. The specific wing folding and unfolding mechanisms are autapomorphic character states of Coleoptera. They were maintained during evolution even though considerable variations of skeletal thoracic structures, musculature and venation occurred. (Additional material is available from the Zoology web page: http://www.urbanfischer.de/journals/zoology).     

The Evolution of Wing Shape in Ornamented-Winged Damselflies (Calopterygidae, Odonata)

Flight has conferred an extraordinary advantage to some groups of animals. Wing shape is directly related to flight performance and evolves in response to multiple selective pressures. In some species, wings have ornaments such as pigmented patches that are sexually selected. Since organisms with pigmented wings need to display the ornament while flying in an optimal way, we might expect a correlative evolution between the wing ornament and wing shape. We examined males from 36 taxa of calopterygid damselflies that differ in wing pigmentation, which is used in sexual displays. We used geometric morphometrics and phylogenetic comparative approaches to analyse whether wing shape and wing pigmentation show correlated evolution. We found that wing pigmentation is associated with certain wing shapes that probably increase the quality of the signal: wings being broader where the pigmentation is located. Our results also showed correlated evolution between wing pigmentation and wing shape in hind wings, but not in front wings, probably because hind wings are more involved in signalling than front wings. The results imply that the evolution of diversity in wing pigmentations and behavioural sexual displays might be an important driver of speciation due to important pre-copulatory selective pressures.     

Homology of the wing base sclerites in Ephemeroptera (Insecta: Pterygota) - a reply to Willkommen and Hörnschemeyer

We revised the homology of wing base structure in Ephemeroptera (Insecta: Pterygota) proposed by Willkommen and Hörnschemeyer in a recent issue of Arthropod Structure and Development. The first free sclerite (s1) in Ephemeroptera should be homologized with a part of the first axillary sclerite (1Ax) of Neoptera, together with the second free sclerite, whereas the authors recognized s1 as a detached part of the anterior notal wing process. The fifth free sclerite of Ephemeroptera should be homologized with the median notal wing process of Neoptera, rather than it being homologous with a part of 1Ax in Neoptera, as the authors postulated. Hypothesized secondary fusion of the axillary sclerites in Ephemeroptera and Odonata proposed by the authors is premature, because the basal phylogeny of Pterygota is still poorly understood, and an alternative interpretation of morphological evolution (i.e., that undifferentiated axillary sclerites represent the ground plan of Pterygota) can also be drawn from the Ephemeroptera + Neoptera hypothesis.     

Wing morphology of a new Cretaceous praying mantis solves the phylogenetic jigsaw of early‐diverging extant lineages

The extremely derived morphology and behaviour of extant praying mantises combined with a scarce record of fossil relatives introduce significant challenges to tracing their evolution from Palaeozoic stem‐dictyopterans. Extant members of Chaeteessidae, Mantoididae and Metallyticidae could be invaluable to resolving the mantodean tree, yet their inclusion in phylogenetic analyses led to conflicting hypotheses due to their highly disparate respective morphologies. In this contribution, we present Labradormantis guilbaulti gen. et sp.n. , a new fossil species described from both fore‐ and hind‐wing imprints discovered in the Redmond Mine locality (Late Cretaceous, Cenomanian, Redmond Formation; Labrador, Canada). The examination of its hind‐wing AA2* supports the hypothesis that this structure, unique to Chaeteessidae among extant mantises, is a true vein and that its occurrence represents a plesiomorphy for Mantodea. A parsimony analysis including newly coded wing‐related characters further established that L. guilbaulti gen. et sp.n. displays a unique combination of plesiomorphic and apomorphic character states that situates it within the extinct family Baissomantidae. This dataset resolved the phylogenetic relationships of early‐diverging extant lineages as (Chaeteessidae (Mantoididae (Metallyticidae, Artimantodea))), and suggested that the Eocene Lithophotina floccosa Cockerell might be a close relative of extant metallyticids. It also indicated a trend towards increased modularity within mantis fore‐wings, in contrast with a trend towards increased morphological integration in their hind‐wings, both of which are potentially associated with improved flight performance for modern mantises. This study emphasizes the importance of fossils for resolving phylogenetic relationships and for introducing transitional phenotypes to infer ancient evolutionary trends of extant derived clades.     

The effects of latitude,body size,and sexual selection on wing shape in a damselfly

Under natural selection, wing shape is expected to evolve to optimize flight performance. However, other selective factors besides flight performance may influence wing shape. One such factor could be sexual selection in wing sexual ornaments, which may lead to alternative variations in wing shape that are not necessarily related to flight performance. In the present study, we investigated wing shape variations in a calopterygid damselfly along a latitudinal gradient using geometric morphometrics. Both sexes show wing pigmentation, which is a known signal trait at intra‐ and interspecific levels. Wing shape differed between sexes and, within the same sex, the shape of the hind wing differed from the front wing. Latitude and body size explained a high percentage of the variation in wing shape for female front and hind wings, and male front wings. In male hind wings, wing pigmentation explained a high amount of the variation in wing shape. On the other hand, the variation in shape explained by pigmentation was very low in females. We suggest that the conservative morphology of front wings is maintained by natural selection operating on flight performance, whereas the sex‐specific differences in hind wings most likely could be explained by sexual selection. The observed sexual dimorphism in wing shape is likely a result of different sex‐specific behaviours. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 263–274.     

The Sharpshooter Genus Geitogonalia Young: Descriptions of a New Brazilian Species and of the Female of Geitogonalia quatuordecimmaculata (Taschenberg) (Hemiptera: Cicadellidae)

The sharpshooter genus Geitogonalia Young was so far known from a single species from Southeastern Brasil—Geitogonalia quatuordecimmaculata (Taschenberg). A new species, Geitogonalia viridis, is described and illustrated in this paper based on males and females from the state of Rio de Janeiro. In addition, the female of G. quatuordecimmaculata is for the first time described and illustrated in detail. Geitogonalia quatuordecimmaculata is a dark species marked with bright orange on the fore wings, whereas the new species has the corium and clavus of the fore wings mostly green. The paraphyses are well developed in G. quatuordecimmaculata, with elongate rami, whereas they are inconspicuous in G. viridis, with the rami modified as a pair of very small sclerites.     

Evolutionary directional asymmetry and shape variation in Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae): an example using hind wings

The western corn rootworm Diabrotica virgifera virgifera LeConte is a pest of maize in the USA and Europe and especially a problem in particular regions of Croatia. In the present study, patterns of variation in hind wing shape were examined. The first objective was to examine the influence of soil type on 10 populations of D. v. virgifera sampled from three regions in Croatia that differed according to edaphic factors and climate. The second objective was to investigate the potential evolutionary presence of directional asymmetry on hind wings. Geometric morphometrics was used to examine these objectives by quantifying the morphological variation within and among individuals and populations. Overall, D. v. virgifera hind wing shape changed according to major soil type classifications in Croatia. The three hind wing morphotypes found varied because of basal radial vein differences, related to landmarks 1, 3, 7, and 14. The findings of the present study show that hind wing shape in D. v. virgifera can be used to differentiate populations based on edaphic factors and may have application as a monitoring tool in the integrated management of D. v. virgifera. In an evolutionary context, the presence of directional asymmetry in the hind wings of D. v. virgifera adds to the ever growing data on the evolution of insect wings. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 110–118.     

Hind Wing Shape Evolves Faster than Front Wing Shape in Calopteryx Damselflies

Wing shape has been shown in a variety of species to be influenced by natural and sexual selection. In damselflies, front- and hind wings can beat independently, and functional differentiation may occur. Males of Calopteryx damselflies show species-specific nuptial flights that differ in colour signalling with the hind wings. Therefore, hind wing shape and colour may evolve in concert to improve colour display, independent of the front wings. We predicted that male hind wing shape evolves faster than front wing shape, due to sexual selection. Females do not engage in sexual displays, so we predicted that females do not show differences in divergence between front- and hind wing shape. We analysed the non-allometric component of wing shape of five European Calopteryx taxa using geometric morphometrics. We found a higher evolutionary divergence of hind wing shape in both sexes. Indeed, we found no significant differences in rate of evolution between the sexes, despite clear sex-specific differences in wing shape. We suggest that evolution of hind wing shape in males is accelerated by sexual selection on pre-copulatory displays and that this acceleration is reflected in females due to genetic correlations that somehow link the rates of wing shape evolution in the two sexes, but not the wing shapes themselves.     

Wing movements in the bush-cricket Tettigonia viridissima and the mantis Ameles spallanziana during natural leaping

The movements of the wings during natural jumps made by Tettigonia viridissima and Ameles spallanziana were analysed by means of high-speed flash photography. Additional data were obtained from the bush-cricket Oecanthus pellucens . In all cases the wings were usually extended before the hind tarsi had left the ground. In most jumps the first downstroke of the wings was completed before take-off and the wings probably contributed directly to initial propulsion. All species showed a 'peel' variation of the 'clap and fling' mechanism in the hind wing downstroke. There was evidence of strong ventral flexure in the forewing at the start of the upstroke in Tettigonia . The implications of the use of the wings in the energetics of jumping are discussed.