Dating in the Dark: Elevated Substitution Rates in Cave Cockroaches (Blattodea: Nocticolidae) Have Negative Impacts on Molecular Date Estimates.

Rates of nucleotide substitution vary substantially across the Tree of Life, with potentially confounding effects on phylogenetic and evolutionary analyses. A large acceleration in mitochondrial substitution rate occurs in the cockroach family Nocticolidae, which predominantly inhabit subterranean environments. To evaluate the impacts of this among-lineage rate heterogeneity on estimates of phylogenetic relationships and evolutionary timescales, we analyzed nuclear ultraconserved elements (UCEs) and mitochondrial genomes from nocticolids and other cockroaches. Substitution rates were substantially elevated in nocticolid lineages compared with other cockroaches, especially in mitochondrial protein-coding genes. This disparity in evolutionary rates is likely to have led to different evolutionary relationships being supported by phylogenetic analyses of mitochondrial genomes and UCE loci. Furthermore, Bayesian dating analyses using relaxed-clock models inferred much deeper divergence times compared with a flexible local clock. Our phylogenetic analysis of UCEs, which is the first genome-scale study to include all 13 major cockroach families, unites Corydiidae and Nocticolidae and places Anaplectidae as the sister lineage to the rest of Blattoidea. We uncover an extraordinary level of genetic divergence in Nocticolidae, including two highly distinct clades that separated ~115 million years ago despite both containing representatives of the genus Nocticola. The results of our study highlight the potential impacts of high among-lineage rate variation on estimates of phylogenetic relationships and evolutionary timescales.

Evolution of reproductive structures for in-flight mating in thynnine wasps (Hymenoptera: Thynnidae: Thynninae).

Thynnine wasps have an unusual mating system that involves concurrent in-flight copulation and nuptial feeding of wingless females by alate males. Consequently, thynnine genitalia play a multifunctional role and have likely been subject to various different selective pressures for both reproductive success and food provisioning. Here, we present a new molecular phylogeny for the Australian Thynninae and use 3D-geometric morphometrics and comparative methods to investigate the morphological evolution of select genital structures across the group. We found significant morphological integration between all male and female structures analysed, which is likely influenced by sexual selection, but also reproductive isolation requirements and mechanical constraints. The morphology of the primary male and female coupling structures was correlated with female body size, and female genitalia exhibited strong negative size allometry. Those male and female coupling structures have evolved at similar evolutionary rates, whereas female structures appear to have evolved a higher degree of morphological novelty over time. We conclude that the unique reproductive strategies of thynnine wasps have resulted in complex evolutionary patterns in their genital morphology, which has likely played a central role in the extensive diversification of the subfamily across Australasia and South America. Our study reinforces the need to treat composite characters such as genitalia by their component parts, and to consider the roles of both male and female reproductive structures in evolutionary studies.

Traumatic insemination in terrestrial arthropods.

Traumatic insemination is a bizarre form of mating practiced by some invertebrates in which males use hypodermic genitalia to penetrate their partner's body wall during copulation, frequently bypassing the female genital tract and ejaculating into their blood system. The requirements for traumatic insemination to evolve are stringent, yet surprisingly it has arisen multiple times within invertebrates. In terrestrial arthropods traumatic insemination is most prevalent in the true bug infraorder Cimicomorpha, where it has evolved independently at least three times. Traumatic insemination is thought to occur in the Strepsiptera and has recently been recorded in fruit fly and spider lineages. We review the putative selective pressures that may have led to the evolution of traumatic insemination across these lineages, as well as the pressures that continue to drive divergence in male and female reproductive morphology and behavior. Traumatic insemination mechanisms and attributes are compared across independent lineages.

Surviving in sympatry: paragenital divergence and sexual mimicry between a pair of traumatically inseminating plant bugs.

Reproductive interactions between species can carry significant costs (e.g., wasted time, energy, and gametes). In traumatically inseminating insects, heterospecific mating costs may be intensified, with indiscriminate mating and damaging genitalia leading to damage or death. When closely related traumatically inseminating species are sympatric, we predict selection should favor the rapid evolution of reproductive isolation. Here we report on a cryptic species of traumatically inseminating plant bug, Coridromius taravao, living sympatrically with its sister species, Coridromius tahitiensis, in French Polynesia. Despite their sister-species relationship, they exhibit striking differences in reproductive morphology, with females of each species stabbed and inseminated through different parts of their abdomens. Furthermore, C. tahitiensis is sexually dimorphic in coloration and vestiture, while both sexes of C. taravao share the C. tahitiensis male expression of these traits. These findings support a role for (1) reproductive character divergence and (2) interspecies sexual mimicry in limiting interspecific mating brought about by indiscriminate male mating behavior.

Female genital concealment and a corresponding male clasping apparatus in Australian ripple bugs (Hemiptera: Veliidae).

Conflicts of interest over reproduction between males and females are widespread in sexually reproducing species. This is exemplified in water striders (Gerridae), where females vigorously resist costly mating attempts, and males and females often exhibit elaborate grasping and anti-grasping morphological traits. Like water striders, their sister-group, the ripple bugs (Veliidae), share similar life histories and are expected to face similar conflicts over mating. Veliids in the genus Nesidovelia exhibit elaborate sexual dimorphism, which is predicted to function in intersexual antagonistic struggles. This includes concealed genitalia in females, and elaborate pregenital abdominal modifications in males. By documenting mating behaviour in Nesidovelia peramoena and freezing pairs in copula, we show that males and females struggle prior to mating, and male abdominal modifications function to gain access to the female's concealed genitalia. This is consistent with, though not limited to, sexual conflict.

Turrana ejuncida, a new species of Acanthocorini (Hemiptera: Heteroptera: Coreidae) from Cape Range, Western Australia, with discussion of its systematic position and host plant associations.

The coreid genus Turrana Distant 1911 is redescribed, and a new species Turrana ejuncida sp. nov. is described from specimens collected from Cape Range National Park, Western Australia in 2019 and 2021. Habitus photographs and scanning electron microscopy images are presented of key characters, with X-Ray microtomography deployed to document the male and female genitalia. In addition, DNA barcodes for mitochondrial gene regions COI and 16S were obtained and are made available on Genbank. Finally, the evidence provided in this work is discussed in relation to the systematic position of Turrana.

Taxonomic notes on the Australian skyhopper genus Kosciuscola Sjstedt (Orthoptera: Acrididae: Oxyinae).

The Australian skyhopper genus Kosciuscola Sjstedt consists of brachypterous species that inhabit the Australian alpine and subalpine region. The genus used to include 5 species and 1 subspecies, but according to a recent phylogenomic study, there could be as many as 14 species in the genus, that are genetically and geographically isolated from each other. This study represents the first step in describing and documenting the diversity of this interesting genus. In this study, we redefine the type species K. tristis, and elevate its subspecies K. tristis restrictus as a valid species on the basis of distinct morphological traits, geographical isolation, and phylogenomic evidence.

Sexual coevolution in the traumatically inseminating plant bug genus Coridromius.

Sexual conflict has recently been proposed as a driving force behind the rapid diversification of genitalia among sexually reproducing organisms. In traumatically inseminating insects, males stab females in the side of the body with needle-like genitalia, ejaculating into their body cavity. Such mating is costly to females and has led to the evolution of cost-reducing 'paragenitalia' in some species. Whereas some consider this evidence of sexually antagonistic coevolution, others remain unconvinced. Variation in the reproductive morphology of both sexes - particularly males - is alleged to be negligible, contradicting the expectations of a coevolutionary arms race. Here, we use a phylogeny of the traumatically inseminating plant bug genus Coridromius to show that external female paragenitalia have evolved multiply across the genus and are correlated with changes in male genital shape. This pattern is characteristic of an evolutionary arms race driven by sexual conflict.

A comprehensive and user-friendly framework for 3D-data visualisation in invertebrates and other organisms.

Methods for 3D-imaging of biological samples are experiencing unprecedented development, with tools such as X-ray micro-computed tomography (µCT) becoming more accessible to biologists. These techniques are inherently suited to small subjects and can simultaneously image both external and internal morphology, thus offering considerable benefits for invertebrate research. However, methods for visualising 3D-data are trailing behind the development of tools for generating such data. Our aim in this article is to make the processing, visualisation and presentation of 3D-data easier, thereby encouraging more researchers to utilise 3D-imaging. Here, we present a comprehensive workflow for manipulating and visualising 3D-data, including basic and advanced options for producing images, videos and interactive 3D-PDFs, from both volume and surface-mesh renderings. We discuss the importance of visualisation for quantitative analysis of invertebrate morphology from 3D-data, and provide example figures illustrating the different options for generating 3D-figures for publication. As more biology journals adopt 3D-PDFs as a standard option, research on microscopic invertebrates and other organisms can be presented in high-resolution 3D-figures, enhancing the way we communicate science.

A Dynamic Optical Signal in a Nocturnal Moth.

The wings of butterflies and moths generate some of the most spectacular visual displays observed in nature [1-3]. Particularly striking effects are seen when light interferes with nanostructure materials in the wing scales, generating bright, directional colors that often serve as dynamic visual signals [4]. Structural coloration is not known in night-flying Lepidoptera, yet here we show a highly unusual form of wing coloration in a nocturnal, sexually dimorphic moth, Eudocima materna (Noctuidae). Males feature three dark wing patches on the dorsal forewings, and the apparent size of these patches strongly varies depending on the angle of the wing to the viewer. These optical special effects are generated using specialized wing scales that are tilted on the wing and behave like mirrors. At near-normal incidence of light, these "mirror scales" act as thin-film reflectors to produce a sparkly effect, but when light is incident at ∼20°-30° from normal, the reflectance spectrum is dominated by the diffuse scattering of the underlying, black melanin-containing scales, causing a shape-shifting effect. The strong sexual dimorphism in the arrangement and architecture of the scale nanostructures suggests that these patterns might function for sexual signaling. Flickering of the male's wings would yield a flashing, supernormal visual stimulus [5] to a viewer located 20°-30° away from the vertical, while being invisible to a viewer directly above the animal. Our findings reveal a novel use of structural coloration in nature that yields a dynamic, time-dependent achromatic optical signal that may be optimized for visual signaling in dim light.

Ferocious fighting between male grasshoppers.

Contests among individuals over mating opportunities are common across diverse taxa, yet physical conflict is relatively rare. Due to the potentially fatal consequences of physical fighting, most animals employ mechanisms of conflict resolution involving signalling and ritualistic assessment. Here we provide the first evidence of ubiquitous escalated fighting in grasshoppers. The chameleon grasshopper (Kosciuscola tristis) is an Australian alpine specialist, in which males engage in highly aggressive combat over ovipositing females. We describe discrete agonistic behaviours including mandible flaring, mounting, grappling, kicking and biting, and their use depending on the individual's role as challenger or defender. We show that male role predicts damage, with challengers being more heavily damaged than males defending females (defenders). Challengers also possess wider mandibles than defenders, but are similar in other metrics of body size. Our data suggest that fights escalate between males matched in body size and that mandibles are used as weapons in this species. This system represents an exciting opportunity for future research into the evolution of costly fighting behaviour in an otherwise placid group.

Traumatic insemination in the plant bug genus Coridromius Signoret (Heteroptera: Miridae).

In traumatic insemination, males pierce females with hypodermic genitalia and ejaculate into the body cavity rather than into the genital tract. This has resulted in the evolution of female counter-adaptations in the form of paragenitalia to reduce the direct physical costs of mating. While rare in the animal kingdom, traumatic insemination is oddly prevalent in the true bug infraorder Cimicomorpha (Heteroptera), where it occurs in six families and is thought to have arisen twice. Here, we report the discovery of traumatic insemination and elaborate paragenital development in the plant bug genus Coridromius (Miridae), representing a third, independent emergence of traumatic insemination in this infraorder.