The Complete Mitogenomes of Three Grasshopper Species with Special Notes on the Phylogenetic Positions of Some Related Genera

Clarifying phylogenetic position and reconstructing robust phylogeny of groups using various evidences are an eternal theme for taxonomy and systematics. In this study, the complete mitogenomes of Longzhouacris mirabilis, Ranacris albicornis, and Conophyma zhaosuensis were sequenced using next-generation sequencing (NGS), and the characteristics of the mitogenomes are presented briefly. The mitogenomes of the three species are all circular molecules with total lengths of 16,164 bp, 15,720 bp, and 16,190 bp, respectively. The gene structures and orders, as well as the characteristics of the mitogenomes, are similar to those of other published mitogenomes in Caelifera. The phylogeny of the main subfamilies of Acrididae with prosternal process was reconstructed using a selected dataset of mitogenome sequences under maximum likelihood (ML) and Bayesian inference (BI) frameworks. The results showed that the genus Emeiacris consistently fell into the subfamily Melanoplinae rather than Oxyinae, and the genus Choroedocus had the closest relationship with Shirackiacris of the subfamily Eyprepocnemidinae in both phylogenetic trees deduced from mitogenome protein coding genes (PCGs). This finding is entirely consistent with the morphological characters, which indicate that Emeiacris belongs to Melanoplinae and Choroedocus belongs to Eyprepocnemidinae. In addition, the genera Conophymacris and Xiangelilacris, as well as Ranacris and Menglacris, are two pairs of the closest relatives, but their phylogenetic positions need further study to clarify.

Aposematic coloration from Mid-Cretaceous Kachin amber

Aposematic coloration is among the most diverse antipredator strategies, which can signal unpleasantness of organisms to potential predators and reduce the probability of predation. Unlike mimesis, aposematic coloration allows organisms to warn their predators away by conspicuous and recognizable colour patterns. However, aposematism has been a regular puzzle, especially as the long-term history of such traits is obscured by an insufficient fossil record. Here, we report the discovery of aposematic coloration in an orthopteran nymph from Mid-Cretaceous Kachin amber (99 million years old). It is attributed to the extinct family Elcanidae and erected as a new genus identified by conspicuous dark/light-striped coloration, four apical spurs on the metatibia, a two-segmented metatarsus and unsegmented stylus. It represents the first fossil orthopteran preserved with aposematic coloration from the Mesozoic, demonstrating that orthopterans had evolved aposematism by the Mid-Cretaceous. Our findings provide novel insights into the early evolution of anti-predator strategies among orthopterans. Together with mimesis, debris-carrying camouflage and aposematism previously reported, our findings demonstrate the relative complexity of prey-predator interactions in the Mesozoic, especially in the Mid-Cretaceous Kachin amber forest. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.

A taxonomic outline of the Poecilimon affinis complex (Orthoptera) using the geometric morphometric approach

The genus Poecilimon contains 145 species, widely distributed in the Palaearctic, among which the Poecilimon ornatus group has the greatest diversity in the Balkans. Despite several revisions of the genus, the systematics of the species group, and in particular, of the taxa associated with the species Poecilimon affinis, is still unsolved. Due to morphological similarity, P. affinis with its subspecies, P. nonveilleri and P. pseudornatus form the Poecilimon affinis complex. The aim of this study is to test the hypotheses of an outlined species complex, namely the P. affinis complex, within the P. ornatus group using morphological data. Geometric analysis was conducted to explore variation in the structure of the male tegmen, ovipositor, male cercus, and male pronotum. The number of teeth and stridulatory file measurements provided additional information on morphological variation within the complex. A phylogenetic tree based on the cytochrome c oxidase subunit I gene (COI) was used for comparison with the morphological data. Canonical variate analysis showed that male tegmen and male cercus are good morphostructures to distinguish the taxa belonging to the P. affinis complex from other species in the P. ornatus group. This may confirm our assumption for the designation of the P. affinis complex. The results of the principal component analysis of stridulatory file measurements, molecular data, and CVA of the ovipositor suggest adding two additional species to the complex: P. ornatus and P. hoelzeli.

Trade-off between flight capability and reproduction in Acridoidea (Insecta: Orthoptera)

In many insect taxa, there is a well-established trade-off between flight capability and reproduction. The wing types of Acridoidea exhibit extremely variability from full length to complete loss in many groups, thus, provide a good model for studying the trade-off between flight and reproduction. In this study, we completed the sampling of 63 Acridoidea species, measured the body length, wing length, body weight, flight muscle weight, testis and ovary weight, and the relative wing length (RWL), relative flight muscle weight (RFW), and gonadosomatic index (GSI) of different species were statistically analyzed. The results showed that there were significant differences in RWL, RFW, and GSI among Acridoidea species with different wing types. RFW of long-winged species was significantly higher than that of short-winged and wingless species (p < .01), while GSI of wingless species was higher than that of long-winged and short-winged species. The RWL and RFW had a strong positive correlation in species with different wing types (correlation coefficient r = .8344 for male and .7269 for female, and p < .05), while RFW was strong negatively correlated with GSI (r = -.2649 for male and -.5024 for female, and p < .05). For Acridoidea species with wing dimorphism, males with relatively long wings had higher RFW than that of females with relatively short wings, while females had higher GSI. Phylogenetic comparative analysis showed that RWL, RFW, and GSI all had phylogenetic signals and phylogenetic dependence. These results revealed that long-winged individuals are flight capable at the expense of reproduction, while short-winged and wingless individuals cannot fly, but has greater reproductive output. The results support the trade-off between flight and reproduction in Acridoidea.

A tree of leaves: Phylogeny and historical biogeography of the leaf insects (Phasmatodea: Phylliidae)

The insect order Phasmatodea is known for large slender insects masquerading as twigs or bark. In contrast to these so-called stick insects, the subordinated clade of leaf insects (Phylliidae) are dorso-ventrally flattened and therefore resemble leaves in a unique way. Here we show that the origin of extant leaf insects lies in the Australasian/Pacific region with subsequent dispersal westwards to mainland Asia and colonisation of most Southeast Asian landmasses. We further hypothesise that the clade originated in the Early Eocene after the emergence of angiosperm-dominated rainforests. The genus Phyllium to which most of the ~100 described species pertain is recovered as paraphyletic and its three non-nominate subgenera are recovered as distinct, monophyletic groups and are consequently elevated to genus rank. This first phylogeny covering all major phylliid groups provides the basis for future studies on their taxonomy and a framework to unveil more of their cryptic and underestimated diversity.

Phylogenetic position of the genera Caryandoides, Paratoacris, Fer and Longchuanacris (Orthoptera:Acrididae) revealed by complete mitogenome sequences

Many taxa in the Acrididae have controversial phylogenetic positions. A typical example of such controversies is the phylogenetic positions of the genera Caryandoides, Paratoacris, Fer and Longchuanacris, as well as some other related taxa, which were placed in Oxyinae by some authors, but were considered members of the subfamily Catantopinae by others. In this study, the complete mitogenomes of nine species were sequenced using next-generation sequencing, the characteristics of the newly sequenced mitogenomes are presented briefly, and the phylogeny of the Oxyinae and Catantopinae are reconstructed using a selected dataset of mitogenome sequences under maximum likelihood and Bayesian inference frameworks. The results show that the four controversial genera were consistently assigned to the subfamily Oxyinae rather than Catantopinae in all phylogenetic trees deduced from different datasets under different frameworks, and this finding is entirely consistent with their morphological characters. Therefore, it is more appropriate to place them in Oxyinae rather than Catantopinae. In addition, the results from our analysis also confirm the membership of the genus Apalacris in Coptacrinae rather than Catantopinae, and indicate the uncertainty in the phylogenetic position of the genus Traulia, and a more in-depth study is necessary to resolve the relationship of Traulia with other catantopine groups or Coptacrinae.

A unique camouflaged mimarachnid planthopper from mid-Cretaceous Burmese amber

Predation is a major driving force for the evolution of functional forms. Avoidance of visual predators has resulted in different kinds of anti-predator defences, such as: camouflage, crypsis, disruptive coloration, and masquerade or mimesis. Camouflage is one of the forms involving shape, colouration, structure and behaviour when the visual pattern and orientation of an animal can determine whether it lives or dies. Inferring the behaviour and function of an ancient organism from its fossilised remains is a difficult task, but in many cases it closely resembles that of its descendants on uniformitarian grounds. Here we report and discuss examples of morphological and behavioural traits involving camouflage named recently as a flatoidinisation syndrome, shown by the inclusion of a planthopper in mid-Cretaceous Burmese amber. We found a new genus and species of an extinct Cretaceous planthopper family Mimarachnidae showing peculiar complex morphological adaptations to camouflage it on tree bark. Due to convergence, it resembles an unrelated tropiduchid planthopper from Eocene Baltic amber and also a modern representatives of the planthopper family Flatidae. Flattening of the body, the horizontal position of the tegmina at repose, tegmina with an undulating margin and elevated, wavy longitudinal veins, together with colouration and more sedentary behavioral traits enable these different insects to avoid predators. Our discovery reveals flatoidinisation syndrome in mid-Cretaceous Burmese amber which may provide insights into the processes of natural selection and evolution in this ancient forest.

Digest: Ecomorphological convergence across the Atlantic

Did the remarkable helicopter damselflies (family Pseudostigmatidae) evolve their unique feeding and oviposition behaviors independently on two continents? In this issue, Toussaint et al. use molecular phylogenetic approaches to provide convincing evidence that these "forest giants" are in fact an example of ecomorphological convergence across the Atlantic Ocean.