A general theory of genital homologies for the Hexapoda (Pancrustacea) derived from skeletomuscular correspondences, with emphasis on the Endopterygota

Comparative morphology of male genitalia in antlions (Insecta, Neuroptera, Myrmeleontidae), with emphasis on owlflies (Ascalaphinae) and a possible structural evolutionary scenario

Male genitalia morphology in Myrmeleontidae has traditionally been insufficiently studied, although it has received increased attention for its diagnostic value in recent times. A neutral terminology has generally been applied in standard taxonomic practice, yet knowledge of an equivalent and stable terminology across taxa based on comparative morphology has been missing. Herein a detailed comparative morphology study with examples from most tribes within Myrmeleontidae, including owlflies (Ascalaphinae), attempts to relate external and internal genital structures based on a proposed groundplan for Neuroptera and Myrmeleontidae. We contend that a groundplan based on 10 abdominal segments, plus vestigial structures from an 11th segment, coherently depicts structural components across myrmeleontid taxa. A gonarcus, an element of Neuropterida amply referred in Neuroptera, is supported to represent the pair of abdominal appendages of segment X medially fused, with gonocoxite and gonostylus components. In most myrmeleontid taxa, basal (gonocoxites) and distal (gonostyli) components separate, with gonostyli positioned posteriorly with respect to gonocoxites, still united with translucent, lightly sclerotized tissue, forming a more or less conical structure, a proposed synapomorphy for the family. Ninth gonostyli are generally reduced (pulvini) and have migrated close to the base of gonarcus (10th gonocoxites). A pelta, also a potential synapomorphy for Myrmeleontidae, derives from paired setose surfaces of the 10th gonostyli, medially positioned (still evident in Bubopsis). Three structural types of gonarcus are diagnosed for illustrative purposes, as they may represent convergent constructs.

The puncture mechanics: an example from the bed bug Cimex lectularius showing traumatic insemination using the paramere

Cimicidae are well-known for traumatic insemination, and males pierce females with their parameres and transfer sperm through them. The shape of parameres is relatively stable in the family, but in some genera, the paramere is elongated, appearing less resistant against lateral deflection. To understand the mechanical limitations of the paramere, we studied its penetration mechanics of the common bed bug, Cimex lectularius. We examined the post-abdominal morphology, paramere geometry and material properties and conducted breaking stress experiments on the paramere under wet and dry conditions. Mechanical property gradients are present with the paramere tip as the stiffest region and the base as the most flexible one. These mechanical properties relate to the presence of Ca, Zn and Si. The basal wing-shaped structure is flexible, enabling it to interlock with the anal region during mating. The paramere is slightly twisted; the tip region is circular in cross-section, and the geometry of the rest is rather complex. In the mechanical tests, wet parameres mainly buckled, while dried parameres broke off. The level of structural failures depended on directions from which the compression forces were applied. Structural, material and mechanical strengthening mechanisms preventing the paramere from mechanical failure are discussed.

Systematic revision of the ant subfamily Leptanillinae (Hymenoptera, Formicidae)

The genus-level taxonomy of the ant subfamily Leptanillinae (Hymenoptera: Formicidae) is here revised, with the aim of delimiting genus-level taxa that are reciprocally monophyletic and readily diagnosable based upon all adult forms. This new classification reflects molecular phylogenetics and is informed by joint consideration of both male and worker morphology. Three valid genera are recognized in the Leptanillinae: Opamyrma, Leptanilla (= Scyphodonsyn. nov., Phaulomyrma, Leptomesites, Noonillasyn. nov., Yavnellasyn. nov.), and Protanilla (= Anomalomyrmasyn. nov., Furcotanilla). Leptanilla and Protanilla are further divided into informal, monophyletic species groups. Synoptic diagnoses are provided for all genera and informal supraspecific groupings. In addition, worker-based keys to all described species within the Leptanillinae for which the worker caste is known are provided; and male-based keys to all species for which males are known, plus undescribed male morphospecies for which molecular data are published. The following species are described as new: Protanillawallaceisp. nov., Leptanillaacherontiasp. nov., Leptanillabelantansp. nov., Leptanillabethyloidessp. nov., and Leptanillanajaphallasp. nov.

Performance of tree-building methods using a morphological dataset and a well-supported Hexapoda phylogeny

Recently, many studies have addressed the performance of phylogenetic tree-building methods (maximum parsimony, maximum likelihood, and Bayesian inference), focusing primarily on simulated data. However, for discrete morphological data, there is no consensus yet on which methods recover the phylogeny with better performance. To address this lack of consensus, we investigate the performance of different methods using an empirical dataset for hexapods as a model. As an empirical test of performance, we applied normalized indices to effectively measure accuracy (normalized Robinson-Foulds metric, nRF) and precision, which are measured via resolution, one minus Colless' consensus fork index (1-CFI). Additionally, to further explore phylogenetic accuracy and support measures, we calculated other statistics, such as the true positive rate (statistical power) and the false positive rate (type I error), and constructed receiver operating characteristic plots to visualize the relationship between these statistics. We applied the normalized indices to the reconstructed trees from the reanalyses of an empirical discrete morphological dataset from extant Hexapoda using a well-supported phylogenomic tree as a reference. Maximum likelihood and Bayesian inference applying the k-state Markov (Mk) model (without or with a discrete gamma distribution) performed better, showing higher precision (resolution). Additionally, our results suggest that most available tree topology tests are reliable estimators of the performance measures applied in this study. Thus, we suggest that likelihood-based methods and tree topology tests should be used more often in phylogenetic tree studies based on discrete morphological characters. Our study provides a fair indication that morphological datasets have robust phylogenetic signal.

A revised terminology for male genitalia in Hymenoptera (Insecta), with a special emphasis on Ichneumonoidea

Applying consistent terminology for morphological traits across different taxa is a highly pertinent task in the study of morphology and evolution. Different terminologies for the same traits can generate bias in phylogeny and prevent correct homology assessments. This situation is exacerbated in the male genitalia of Hymenoptera, and specifically in Ichneumonoidea, in which the terminology is not standardized and has not been fully aligned with the rest of Hymenoptera. In the current contribution, we review the terms used to describe the skeletal features of the male genitalia in Hymenoptera, and provide a list of authors associated with previously used terminology. We propose a unified terminology for the male genitalia that can be utilized across the order and a list of recommended terms. Further, we review and discuss the genital musculature for the superfamily Ichneumonoidea based on previous literature and novel observations and align the terms used for muscles across the literature.

A new Neotropical ant species of genus Linepithema Mayr (Hymenoptera, Formicidae, Dolichoderinae) with partial revision of the L.fuscum group based on males

The genus Linepithema was erected by Mayr (1866) for his male-based species L.fuscum. In this study a new species is described also based on male morphology, L.paulistanasp. nov., collected in the city of São Paulo, Brazil, which is attributed to the fuscum group (Formicidae: Dolichoderinae). Linepithemapaulistanasp. nov. is the only species of fuscum group present in the eastern part of South America. It is easily distinguishable from the other species of the group because of the presence of a triangular volsellar tooth, which is distally situated between the digitus and the basivolsellar process. By using SEM and optical microscopy, the external genitalia of L.paulistanasp. nov. were analyzed and illustrated and some characters and previous interpretations have been re-evaluated in the Linepithemafuscum group. The male external genitalia are also comparatively analyzed in three species representative of the three Linepithema species groups, those of fuscum, humile, and neotropicum. The present work confirms that the morphological characters of male ants, especially those of male external genitalia, are effective for the identification of genera or species. Given the discrete morphological differences between the external genitalia of the fuscum group and the other species of this genus, a re-evaluation of the generic status of Linepithema is suggested.

Genomic-Phenomic Reciprocal Illumination: Desyopone hereon gen. et sp. nov., an Exceptional Aneuretine-like Fossil Ant from Ethiopian Amber (Hymenoptera: Formicidae: Ponerinae)

Fossils are critical for understanding the evolutionary diversification, turnover, and morphological disparification of extant lineages. While fossils cannot be sequenced, phenome-scale data may be generated using micro-computed tomography (µ-CT), thus revealing hidden structures and internal anatomy, when preserved. Here, we adduce the male caste of a new fossil ant species from Miocene Ethiopian amber that resembles members of the Aneuretinae, matching the operational definition of the subfamily. Through the use of synchrotron radiation for µ-CT, we critically test the aneuretine-identity hypothesis. Our results indicate that the new fossils do not belong to the Aneuretinae, but rather the Ponerini (Ponerinae). Informed by recent phylogenomic studies, we were able to place the fossils close to the extant genus Cryptopone based on logical character analysis, with the two uniquely sharing absence of the subpetiolar process among all ponerine genera. Consequently, we: (1) revise the male-based key to the global ant subfamilies; (2) revise the definitions of Aneuretinae, Ponerinae, Platythyreini, and Ponerini; (3) discuss the evolution of ant mandibles; and (4) describe the fossils as †Desyopone hereon gen. et sp. nov. Our study highlights the value of males for ant systematics and the tremendous potential of phenomic imaging technologies for the study of ant evolution.

Ants (Hymenoptera: Formicidae) from Miocene Ethiopian amber: filling gaps in the geological record of African terrestrial biota

The Early Miocene (16–23 Mya) amber of Ethiopia constitutes a new source of fossil ants for Africa, where they are otherwise poorly documented. Here we report a diversified assemblage of six subfamilies and at least 19 genera that are still predominantly alive in the Afrotropics today. In this first account, a particular reference is made to the subfamily Dolichoderinae, with the description of two new species: Technomyrmex svojtkai Perrichot & Engel sp. nov. and Ravavy goldmani Boudinot & Perrichot sp. nov. The first is illustrated and described based on synchrotron-radiation microcomputed tomography, and the second represents the first fossil record for the tribe Bothriomyrmecini and Ravavy, a Malagasy and Afrotropical genus that was hitherto monotypic. The ant composition in Ethiopian amber is congruent with the global pattern emerging across ants and showing a Neogene diversification almost exclusively within extant genera.

Evolutionary history of sexual differentiation mechanism in insects

Alternative splicing underpins functional diversity in proteins and the complexity and diversity of eukaryotes. An example is the doublesex gene, the key transcriptional factor in arthropod sexual differentiation. doublesex is controlled by sex-specific splicing and promotes both male and female differentiation in holometabolan insects, whereas in hemimetabolan species, doublesex has sex-specific isoforms but is not required for female differentiation. How doublesex evolved to be essential for female development remains largely unknown. Here, we investigate ancestral states of doublesex using Thermobia domestica belonging to Zygentoma, the sister group of Pterygota, that is, winged insects. We find that, in T. domestica, doublesex expresses sex-specific isoforms but is only necessary for male differentiation of sexual morphology. This result supports the hypothesis that doublesex initially promoted male differentiation during insect evolution. However, T. domestica doublesex has a short female-specific region and upregulates the expression of vitellogenin homologs in females, suggesting that doublesex may already play some role in female morphogenesis of the common ancestor of Pterygota. Reconstruction of the ancestral sequence and prediction of protein structures show that the female-specific isoform of doublesex has an extended C-terminal disordered region in holometabolan insects but not in nonholometabolan species. We propose that doublesex acquired its function in female morphogenesis through a change in the protein motif structure rather than the emergence of the female-specific exon.

A standardized nomenclature and atlas of the female terminalia of Drosophila melanogaster

The model organism Drosophila melanogaster has become a focal system for investigations of rapidly evolving genital morphology as well as the development and functions of insect reproductive structures. To follow up on a previous paper outlining unifying terminology for the structures of the male terminalia in this species, we offer here a detailed description of the female terminalia of D. melanogaster. Informative diagrams and micrographs are presented to provide a comprehensive overview of the external and internal reproductive structures of females. We propose a collection of terms and definitions to standardize the terminology associated with the female terminalia in D. melanogaster and we provide a correspondence table with the terms previously used. Unifying terminology for both males and females in this species will help to facilitate communication between various disciplines, as well as aid in synthesizing research across publications within a discipline that has historically focused principally on male features. Our efforts to refine and standardize the terminology should expand the utility of this important model system for addressing questions related to the development and evolution of animal genitalia, and morphology in general.

The evolution of insect biodiversity

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

On the value of Burmese amber for understanding insect evolution: Insights from †Heterobathmilla - an exceptional stem group genus of Strepsiptera (Insecta)

Burmese amber and amber from other periods and regions became a rich source of new extinct insect species and yielded important insights in insect evolution in the dimension of time. Amber fossils have contributed to the understanding of the phylogeny, biology, and biogeography of insects and other groups, and have also gained great importance for dating molecular trees. Another major potential is the documentation of faunal, floral and climatic shifts. Evolutionary transitions can be well-documented in amber fossils and can reveal anatomical transformations and the age of appearance of structural features. Here, using a new stem group species of Strepsiptera from Burmite, we evaluate this potential of amber insect fossils to assess the current phylogeny of Strepsiptera, with the main emphasis on the early splitting events in the stem group. Amber fossils have greatly contributed to the understanding of the evolution of Strepsiptera in the late Mesozoic and the Cenozoic. †Heterobathmilla kakopoios Pohl and Beutel gen. et sp. n. described here is placed in the stem group of the order, in a clade with †Kinzelbachilla (†Kinzelbachillidae) and †Phthanoxenos (†Phthanoxenidae). †Phthanoxenidae has priority over †Kinzelbachillidae, and the latter is synonymised. The superb details available from this new fossil allowed us to explore unique features of the antennae, mouthparts, and male copulatory apparatus, and to provide a phylogenetic hypothesis for the order. The younger †Protoxenos from Eocene Baltic amber was confirmed as sister to all remaining extinct and extant groups of Strepsiptera, whereas the position of the Cretaceous †Cretostylops in the stem group remains ambivalent. While the value of Burmite and amber from other periods has a recognized impact on our knowledge of the evolution in various lineages, this new fossil does not fundamentally change our picture of the phylogeny and evolution of early Strepsiptera. However, it offers new insights into the morphological diversity in the early evolution of the group.

Anatomy and evolution of the head of Dorylus helvolus (Formicidae: Dorylinae): Patterns of sex- and caste-limited traits in the sausagefly and the driver ant

Ants are highly polyphenic Hymenoptera, with at least three distinct adult forms in the vast majority of species. Their sexual dimorphism, however, is overlooked to the point of being a nearly forgotten phenomenon. Using a multimodal approach, we interrogate the near total head microanatomy of the male of Dorylus helvolus, the "sausagefly," and compare it with the conspecific or near-conspecific female castes, the "driver ants." We found that no specific features were shared uniquely between the workers and males to the exclusion of the queens, indicating independence of male and worker development; males and queens, however, uniquely shared several features. Certain previous generalizations about ant sexual dimorphism are confirmed, while we also discover discrete muscular presences and absences, for which reason we provide a coarse characterization of functional morphology. Based on the unexpected retention of a medial carinate line on the structurally simplified mandible of the male, we postulate a series of developmental processes to explain the patterning of ant mandibles. We invoke functional and anatomical principles to classify sensilla. Critically, we observe an inversion of the expected pattern of male-queen mandible development: male Dorylus mandibles are extremely large while queen mandibles are poorly developed. To explain this, we posit that the reproductive-limited mandible phenotype is canalized in Dorylus, thus partially decoupling the queen and worker castes. We discuss alternative hypotheses and provide further comparisons to understand mandibular evolution in army ants. Furthermore, we hypothesize that the expression of the falcate phenotype in the queen is coincidental, that is, a "spandrel," and that the form of male mandibles is also generally coincidental across the ants. We conclude that the theory of ant development and evolution is incomplete without consideration of the male system, and we call for focused study of male anatomy and morphogenesis, and of trait limitation across all castes.

Synonymisation of the male-based ant genus Phaulomyrma (Hymenoptera:Formicidae) with Leptanilla based upon Bayesian total-evidence phylogenetic inference

Although molecular data have proven indispensable in confidently resolving the phylogeny of many clades across the tree of life, these data may be inaccessible for certain taxa. The resolution of taxonomy in the ant subfamily Leptanillinae is made problematic by the absence of DNA sequence data for leptanilline taxa that are known only from male specimens, including the monotypic genus Phaulomyrma Wheeler & Wheeler. Focusing upon the considerable diversity of undescribed male leptanilline morphospecies, the phylogeny of 35 putative morphospecies sampled from across the Leptanillinae, plus an outgroup, is inferred from 11 nuclear loci and 41 discrete male morphological characters using a Bayesian total-evidence framework, with Phaulomyrma represented by morphological data only. Based upon the results of this analysis Phaulomyrma is synonymised with Leptanilla Emery, and male-based diagnoses for Leptanilla that are grounded in phylogeny are provided, under both broad and narrow circumscriptions of that genus. This demonstrates the potential utility of a total-evidence approach in inferring the phylogeny of rare extant taxa for which molecular data are unavailable and begins a long-overdue systematic revision of the Leptanillinae that is focused on male material.

Variability and distribution of the golden-headed weevil Compsus auricephalus (Say) (Curculionidae: Entiminae: Eustylini)

Background

The golden-headed weevil Compsus auricephalus is a native and fairly widespread species across the southern U.S.A. extending through Central America south to Panama. There are two recognised morphotypes of the species: the typical green form, with pink to cupreous head and part of the legs and the uniformly white to pale brown form. There are other Central and South American species of Compsus and related genera of similar appearance that make it challenging to provide accurate identifications of introduced species at ports of entry.

New information

Here, we re-describe the species, provide images of the habitus, miscellaneous morphological structures and male and female genitalia. We discuss the morphological variation of Compsus auricephalus across its distributional range, by revising and updating its distributional range, based on data from entomological collections in the U.S.A. and Canada. The revised distribution of C. auricephalus extends as far south as Zacapa in Guatemala. Records south from there correspond to a different species, with affinities to C. auricephalus that we discuss and illustrate. We also discuss morphological affinities and differences with other similar species. Furthermore, we summarise information regarding the biology, host plants and natural enemies of C. auricephalus.

Revealing male genital morphology in the giant ant genus Dinoponera with geometric morphometrics

Genitalia include some of the most complex and morphologically diverse structures in insects, finding extensive use in taxonomy, but ant taxonomy is female biased and knowledge of the males is little explored, potentially depriving ant taxonomy of valuable information. We examine the male genital morphology of six species of Dinoponera and the variation among species and within species is described. We performed geometric morphometric analyses for the penisvalvae and lateropenite of the volsella. The results from the descriptions and statistical analyses show the genitalia offer valuable characters for species delimitation. What is presently known as Dinoponera australis can be differentiated into discrete populations, perhaps some representing cryptic species. The similarities between D. australis and D. snellingi suggest a close relation between them as well as between D. gigantea and D. quadriceps. We conclude that several genital characters, especially those of the penisvalvae, can be used to differentiate the species and might be useful to clarify the taxonomy of Dinoponera.

Male postabdomen reveals ancestral traits of Megasecoptera among winged insects

External male genitalia of insects are greatly diverse in form and frequently used in evolutionary context and taxonomy. Therefore, our proper recognition of homologous structures among various groups from Paleozoic and extant insect taxa is of crucial interest, allowing to understand the key steps in insect evolution. Here, we reveal structural details of two Late Carboniferous representatives of Megasecoptera (families Bardohymenidae and Brodiopteridae), such as the presence of separated coxal plates VIII and ventral expansions of coxal lobes IX. Together with the confirmed presence of abdominal styli in some other members of Palaeodictyopterida (Diaphanopterodea) this suggests that early pterygotes may have had traits more archaic than expected. Whether or not these traits point to a stem-group relationship of Palaeodictyopterida to all other Pterygota as suspected by earlier authors remains unclear at this stage. Furthermore, the present study provides an updated comparison of male postabdomen morphology among extant species of wingless Archaeognatha and representatives of early diverging groups of Pterygota from the Late Carboniferous and Early Permian, the Megasecoptera (Palaeodictyopterida), Permoplectoptera (Ephemeroptera) and Meganisoptera (Odonatoptera).

First description of male genital sclerites and associated musculature for two members of Coniopterygidae (Insecta: Neuropterida: Neuroptera) based on X-ray microCT imaging

Coniopterygidae are the dwarfs among the Neuroptera. Despite their miniaturisation, the males are equipped with genital sclerites that are excessively heterogeneous. They function in copulation and sperm transfer and have been widely utilized for species identification, as well being considered of high phylogenetic relevance. The present study is the first to describe the musculature associated with the genital sclerites of two species of Coniopterygidae, Helicoconis lutea (Wallengren, 1871) (Aleuropteryginae), and Coniopteryx pygmaea (Enderlein, 1906) (Coniopteryginae) based on X-ray microCT imaging. We found six pairs of muscles associated with the genital sclerites in H. lutea and seven in C. pygmaea. The images depict other internal organs of the posterior abdominal segments, such as gonads and alimentary canal. In both investigated species, the internal sclerites support the ductus ejaculatorius, which - surprisingly - turned out to be a landmark for the identification of closely adjacent internal sclerites and associated musculature. The interpretation of these sclerites as gonocoxites and gonapophyses of the tenth segment (traditionally denoted as parameres and penis) could be corroborated. Thus it is no longer tenable to assert that possession of a "penis" is exclusive to Coniopterygidae, since this sclerite is part of the ground pattern in Neuroptera. Interactions of genital sclerites and corresponding musculature during copulation are discussed.

Comparative morphology of clasping structures in predator stink bugs (Hemiptera: Pentatomidae: Asopinae): Insights into their function and evolution

Parameres are male genital structures found in many insects which are often used as clasping devices to exert dominance in copula. The asopines have evolved a remarkable additional pair of similar structures, often denominated processes, which combines with the parameres in a tweezers-like system. Processes in similar positions have also been found in other subfamilies of Pentatomidae, but smaller and less developed. Using scanning electron microscopy, we document the among-species variability found in the clasping structures in asopines. We first revealed a vast diversity of ornamentations, such as sensilla and microsculpture. When present, these ornamentations are invariably found on both, the parameres and processes, and often on the corresponding female parts, the valvifers VIII, indicating a functional role of attachment and sensory perception in copula for the ornamentations. We also show that the processes are drastically different between the Asopinae and non-asopines. Therefore, we suggest the term "pseudoclasper" for the Asopinae processes and "superior process of dorsal rim" for the remaining examined taxa. The pseudoclaspers are directly connected to and attached in the same place as the parameres in asopines, while the superior processes of dorsal rim and parameres are completely disconnected in other pentatomids. These results indicate a non-homologous origin between pseudoclaspers and superior processes of dorsal rim in Pentatomidae.

Copulatory function and development shape modular architecture of genitalia differently in males and females

Genitalia are multitasking structures whose development is mediated by numerous regulatory pathways. This multifactorial nature provides an avenue for multiple sources of selection. As a result, genitalia tend to evolve as modular systems comprising semi-independent subsets of structures, yet the processes that give rise to those patterns are still poorly understood. Here, we ask what are the relative roles of development and function in shaping modular patterns of genitalia within populations and across species of stink-bugs. We found that male genitalia are less integrated, more modular, and primarily shaped by functional demands. In contrast, females show higher integration, lower modularity, and a predominant role of developmental processes. Further, interactions among parts of each sex are more determinant to modularity than those between the sexes, and patterns of modularity are equivalent between and within species. Our results strongly indicate that genitalia have been subjected to sex-specific selection, although male and female genitalia are homologous and functionally associated. Moreover, modular patterns are seemingly constant in the evolutionary history of stink-bugs, suggesting a scenario of multivariate stabilizing selection within each sex. Our study demonstrates that interactions among genital parts of the same sex may be more fundamental to genital evolution than previously thought.

Molecular Phylogeny and Infraordinal Classification of Zoraptera (Insecta)

Zoraptera is a small and predominantly tropical insect order with an unresolved higher classification due to the extremely uniform external body morphology. We, therefore, conducted a multigene molecular phylogeny of extant Zoraptera and critically re-evaluated their morphological characters in order to propose a natural infraordinal classification. We recovered a highly-resolved phylogeny with two main clades representing major evolutionary lineages in Zoraptera, for which we propose family ranks. The two families exhibit striking differences in male genitalia and reproductive strategies. Each family contains two subclades (subfamilies) supported by several morphological synapomorphies including the relative lengths of the basal antennomeres, the number and position of metatibial spurs, and the structure of male genitalia. The newly proposed higher classification of Zoraptera includes the family Zorotypidae stat. revid. with Zorotypinae Silvestri, 1913 (Zorotypus stat. revid., Usazoros Kukalova-Peck and Peck, 1993 stat. restit.) and Spermozorinae subfam. nov. (Spermozoros gen. nov.), and Spriralizoridae fam. nov. with Spiralizorinae subfam. nov. (Spiralizoros gen. nov., Scapulizoros gen. nov., Cordezoros gen. nov., Centrozoros Kukalova-Peck and Peck, 1993, stat. restit., Brazilozoros Kukalova-Peck and Peck, 1993, stat. restit.), and Latinozorinae subfam. nov. (Latinozoros Kukalova-Peck and Peck, 1993, stat. restit.). An identification key and morphological diagnoses for all supraspecific taxa are provided.

Evolution of a hyper-complex intromittent organ in rove beetles – the endophallus of Xantholinini (Staphylinidae: Coleoptera)

Studies on the functional morphology and evolution of genitalia have been crucial to understanding sexual traits in speciation, reproductive isolation and sexual selection in Coleoptera and insects in general. However, the focus of investigation of the intromittent organ of beetles was largely confined to the sclerotized elements of the aedeagus, whereas the membranous structures of the endophallus (=internal sac) have often not been adequately considered. Using a micro-operating technique, we observed living male rove beetles and found five different types of endophallus eversion and related morphological modifications. Analysing genital data of a larger sample of Xantholinini, we could demonstrate that endophallus complexity and modifications tend to vary inversely with the median lobe (penis: intromittent organ). Our comparative morphological study, combined with a molecular phylogenetic analysis, suggests that endophallus spiralling occurring after endophallus eversion is an innovation in beetle evolution.

Using controlled vocabularies in anatomical terminology: A case study with Strumigenys (Hymenoptera: Formicidae)

Morphological studies of insects can help us to understand the concomitant or sequential functionality of complex structures and may be used to hypothetize distinct levels of phylogenetic relationship among groups. Traditional morphological works, generally, have encompassed a set of elements, including descriptions of structures and their respective conditions, literature references and images, all combined in a single document. Fast forward to the digital era, it is now possible to release this information simultaneously but also independently as data sets linked to the original publication in an external environment. In order to link data from various fields of knowledge, disseminating morphological information in an open environment, it is important to use tools that enhance interoperability. For example, semantic annotations facilitate the dissemination and retrieval of phenotypic data in digital environments. The integration of semantic (i.e. web-based) components with anatomic treatments can be used to generate a traditional description in natural language along with a set of semantic annotations. The ant genus Strumigenys currently comprises about 840 described species distributed worldwide. In the Neotropical region, almost 200 species are currently known, but it is possible that much of the species' diversity there remains unexplored and undescribed. The morphological diversity in the genus is high, reflecting an extreme generic reclassification that occurred in the late 20th and early 21st centuries. Here we define the anatomical concepts in this highly diverse group of ants using semantic annotations to enrich the anatomical ontologies available online, focussing on the definition of terms through subjacent conceptualization.

The sperm pump and genital coupling of Panorpodes kuandianensis (Mecoptera: Panorpodidae)

Males of Panorpodidae possess a special sperm pump, through which they directly transfer seminal fluid to the female spermatheca. However, the sperm pump has not been studied in Panorpodes to date. Here, the structure of the sperm pump and the internal coupling of genitalia were investigated in the short-faced scorpionfly Panorpodes kuandianensis Zhong, Zhang, and Hua, 2011 using light and scanning electron microscopy. The sperm pump mainly consists of a piston, a pumping chamber, the anterior region of the aedeagal complex, the posterior region of the ejaculatory sac, and associated muscles. The piston as a propulsion apparatus is controlled by levator and depressor muscles. Its posterior region connects dorsally to the aedeagus via a joint. The pumping chamber is located between the piston and the aedeagus. The dorsal and ventral parameres were attached by retractor muscles. During copulation, the male phallotreme connects to the female copulatory pore to transfer sperm. Male gonostyli and parameres grasp the female to restrict the genitalia movement and impede her medigynium from retreating. The sperm ejaculatory mechanism of Panorpodes and the evolution of sperm transfer mode in insects are briefly discussed based on the structure of the sperm pump and the internal coupling of genitalia.