Systematic Entomology最新文献

Fossils are valuable indicators of the evolutionary history of the clades to which they belong to, especially when they are incorporated as terminal taxa in a total-evidence phylogeny. According to their state of preservation, fossils are often incompletely described for key morphological characters, such as genitalic structures. Here, the internal parts of the genitalia of a male fossil cricket from Cretaceous amber, †Picogryllus carentonensis Josse & Desutter-Grandcolas (Oecanthidae, Podoscirtinae), together with other key morphological characters (i.e., metanotal structures and tibial spurs), were reconstructed for the first time by 3D microtomography. Total-evidence phylogeny and dating combining morphological data (fossils and extant taxa), molecular data (extant taxa only) and time calibration (fossil dates) were performed to evaluate the tempo and mode of evolution of the cricket family Oecanthidae. Divergence time estimates were thus refined and the patterns of transformation for key morphological structures contrasted through the analysis of phylogenetic morphological partitions. Our results show that Oecanthidae date back to the Upper Jurassic (Oxfordian, around 162 Ma) and attest to the presence of the Podoscirtinae in Western Europe during the Lower Cretaceous. Morphological evolution may have been driven by the conquest of new resources (as shown by leg evolution in ancestral Oecanthidae) and/or the ‘conquest of silence’ (as shown by repetitive and definitive losses of acoustic structures). By contrast, genitalia evolution proved more diffuse.

Recent progress in beetle palaeontology has incited us to re-address the evolutionary history of the group. The Permian †Tshekardocoleidae had elytra that covered the posterior body in a loose tent-like manner. The formation of elytral epipleura and a tight fit of elytra and abdomen were important evolutionary transformations in the Middle Permian, resulting in a tightly enclosed subelytral space. Permian families were likely associated with dead wood of gymnospermous trees. The end-Permian extinction event resulted in a turnover in the composition of beetle faunas, especially a decline of large-bodied wood-associated forms. Adephaga and Myxophaga underwent a first wave of diversification in the Triassic. Polyphaga are very rare in this period. The first wave of diversification of this suborder occurs in the Jurassic, with fossils of Elateriformia, Staphyliniformia and Cucujiformia. The Cretaceous fossil record has been tremendously enriched by the discovery of amber inclusions. Numerous fossils represent all major polyphagan lineages and also the remaining suborders. Improved analytical methods for documenting and placing extinct taxa are discussed. Different factors have played a role in the diversification of beetles. The enormous number of species associated with flowering plants, and timing and patterns of diversification in phytophagous lineages indicate that the angiosperm radiation played a major role in beetle macroevolution. Moreover, the evolution of intimate partnerships with symbionts and the acquisition of novel genes—obtained from fungi and bacteria via horizontal gene transfers—facilitated the use of plant material as a food source and were key innovations in the diversification of plant-feeding beetles.

Synthetic studies of arthropod systematics and biodiversity are hindered by overreliance on ‘preferred’ semaphoronts, those life stages (typically adult males) that provide the most taxonomically distinctive characters. However, modern sequence-based methods for inventory have no such limitations and permit incorporation of any and all representatives of a species. Here, we briefly review the growth and potential of these approaches to faunistic and systematic studies and share results from our own recent work that illustrate the value that other morphs, immature stages and females added to these studies.

Natural history collections worldwide house billions of specimens, representing one of the most globally important biobanks. In recent years, the advent of next-generation sequencing has significantly reduced the challenges of obtaining considerable genetic information from historical museum specimens. Crickets in the Australian tribe Eurepini Robillard are a good example of a taxon in which such museomic data have particularly strong potential to advance systematic knowledge, because comprehensive sampling requires decades of work over a very wide area. The tribe currently comprises 64 described species in five genera. Previous studies conflict in the generic relationships inferred for this tribe, all of which are poorly resolved, being based on limited data and sampling. In addition, there has so far been no systematic research for this tribe with extensive taxon sampling, and therefore, the consequence for genus boundaries remains to be investigated. To investigate phylogenetic relationships within Eurepini, we first applied the genome skimming approach to obtain molecular data from a comprehensive sample of Eurepini museum specimens. Of the 69 specimens sampled representing 61 described species, mainly including holotype specimens, we obtained 50 complete and 11 partially complete mitogenomes. Three nuclear genes (H3, 18S, and 28S) were also partially recovered for nearly all of these specimens. Phylogenetic analyses performed with mitogenomes plus three nuclear genes using maximum likelihood and Bayesian inference generated well-supported and highly congruent topologies. Eurepini was strongly recovered monophyletic with eight well-defined groups. These groups are used to revise the systematics of the tribe based on a combination of molecular phylogenetics and morphology. The phylogenetic results support the current definition of three genera (Eurepa Walker, Arilpa Otte & Alexander and Eurepella Otte & Alexander), lead us to redefine three genera (Salmanites Chopard, Napieria Baehr and Piestodactylus Saussure), and define and describe two new genera: Miripella Robillard, Tan & Su gen.nov. and Arrakis Robillard, Tan & Su gen.nov. Our results reinforce the importance of natural history collections as a repository for information on biodiversity and genetics, and provide the first comprehensive and robust phylogenetic framework for future systematic and evolutionary studies of Eurepini.

Sharpshooters (Cicadellinae), a large subfamily of the Cicadellidae, exhibit a global distribution and a broad array of ecological preferences. To explore the phylogenetic relationships and roles of global historical, biotic and biogeographic processes in the diversification of sharpshooters, we analysed DNA sequence data from three mitochondrial and two nuclear genes for 243 taxa representing all Cicadellinae tribes, generic groups, regional faunas and data of geographic distributions of sharpshooter species compiled from online databases and available literature. The maximum likelihood (ML) and Bayesian inference (BI) analyses strongly support the monophyletic clade including Cicadellinae and Phereurininae. Divergence time estimates and biogeographic analyses suggest that sharpshooters originated in the Neotropical region or were more widespread in Gondwana during the Early Cretaceous and diversified through a combination of ancient vicariance and dispersal following the evolution of angiosperm-dominated habitats. The earliest divergence during the Cretaceous gave rise to Oriental and New World lineages, the latter of which subsequently dispersed into the Old World and gave rise to the diverse endemic fauna of Madagascar. The Oriental lineage shows high diversity and endemism in tropical Asia and the Pacific, with striking distributional discontinuities in Wallacea. These results suggest that a combination of environmental and evolutionary factors including continental-scale vicariance, long-distance dispersal and diversification of terrestrial microhabitats and host plants may explain the diversity of the modern sharpshooter fauna.

Water crickets of the subfamily Haloveliinae are semi-aquatic bugs occurring in freshwater and marine habitats throughout the Indo-Australian region, presently including six genera with more than 80 extant species. Whether lineage diversification in Haloveliinae is associated with the utilization of new ecological niches caused by transition events between freshwater and marine habitats remains poorly understood. We investigate the evolutionary history of Haloveliinae using large-scale phylogenomic datasets and a set of novel redefined morphological characters based on 24 ingroup taxa representing all recognized genera. Our phylogenetic results based on the novel datasets definitively indicate that the freshwater genus Strongylovelia Esaki as currently defined is paraphyletic and supports the establishment of a new genus: Metavelia gen. nov., including three congeneric species: Metavelia patiooni comb. nov. (type species), Metavelia priori comb. nov. and Metavelia albicolli comb. nov. Reconstruction of ancestral habitats suggests a freshwater origin for the Haloveliinae. Divergence time estimations reveal that the origin of the monophyletic marine clade occurred at around 83 Ma (95% highest posterior density: 71–98 Ma) in the Late Cretaceous, involving a single transition event from freshwater to marine habitats. This time coincides with the period of high global sea levels in the Late Cretaceous. During this period, the marine incursions caused by the massive sea level rise flooded the continental margins, especially in Southeast Asia, where ancestral Haloveliinae were probably distributed. The appearance of new marine habitats after the marine incursions (e.g., intertidal, mangroves and estuarine) probably led to a subsequent establishment and diversification of the marine lineages.

Grylloidea (crickets) and Gryllotalpoidea (mole crickets and ant crickets) are relatively ancient lineages within Orthoptera but their fossil records are not very rich. They are currently considered sister clades within the Gryllidea but with obvious differences in morphology and ecological adaptations. We report a new gryllidean family, †Pseudogryllotalpidae fam. nov. with three new genera and four new species, viz. †Pseudogryllotalpa scalprata gen. et sp. nov., †Unidigitus longialatus gen. et sp. nov., †Petilus zhengi gen. et sp. nov. and †Chunxiania fascia sp. nov. from the mid-Cretaceous of northern Myanmar (ca. 99 million years ago). Their external and short ovipositors and their modified fossorial forelegs suggest a soil-inhabiting preference. This new family exhibits a series of ‘intermediate’ character states between Grylloidea and Gryllotalpoidea and seems to be a ‘transitional’ fossil group linking these two superfamilies. This new family was resolved as a sister group of the extant Gryllotalpoidea and provides a new insight into the relationship and evolution of Grylloidea and Gryllotalpoidea.

The twisted-winged parasite genus Stylops has a history of different species concepts with varying host specificity resulting in diverse species diversity estimates in different regions of the Holarctic. The adoption of a supergeneralist species concept in Europe, proposing synonymization of all Western Palaearctic Stylops species, did not facilitate taxonomic clarity and obscured the available life-history data in the region for decades. Lack of molecular data has allowed divergent opinions on species hypotheses and little opportunity for evaluating them in this morphologically challenging genus. To solve these discrepancies and gain novel information about host associations, we applied whole-genome sequencing to 163 specimens, representing a significant portion of putative European species. We evaluate the existing and conflicting species hypotheses with molecular species delimitation using Species bOundry Delimitation using Astral (SODA) and use a maximum likelihood phylogeny to investigate host associations of the species. Furthermore, we evaluate the effect of a number of loci used in SODA for the number of inferred species. We find justification for synonymization of multiple species and indications of undescribed species, as well as new host–parasite relationships. We show that the number of inferred species in SODA is exceedingly and positively correlated with the number of loci used, urging for cautious application. The results of our study bring clarity to the Western Palaearctic species diversity of Stylops. Furthermore, the comprehensive molecular dataset generated in this study will be a valuable resource for future studies on Stylops and the evolution of parasites in general.

The transformation of the fore wings into strongly sclerotized protective covers (elytra) is considered a fundamental evolutionary innovation of the megadiverse order Coleoptera. Surprisingly, these multifunctional structures have been reduced in many distantly related groups of beetles. Patterns, drivers and the evolutionary implications of this modification have never been comprehensively discussed. In the present study, we surveyed the entire order Coleoptera to analyse the patterns of elytral shortening and loss, with a special focus on prevalence, forms, degree of reduction and the functional background of this significant deviation from the coleopteran ground plan. Our analysis revealed that about 20% of all extant species (roughly 88,000 out of 442,275 spp.), distributed across all four suborders, have shortened or even absent elytra. The elytral loss was more frequent within the polyphagan series Elateriformia and Staphyliniformia. Moreover, we found that elytral reduction has independently occurred multiple times in the evolutionary history of Coleoptera and that it has been driven by a wide array of selective drivers. One of the main drivers is the improved flexibility of the uncovered abdomen and the correlated increased manoeuvrability in narrow spaces, as well as the option of using the flexible abdomen as a steering organ or to facilitate mating. Another common driver is mimicry, where exposed metathoracic wings potentially improve the overall similarity to hymenopteran models. Exposure of the abdomen can facilitate the targeted release of defensive abdominal gland secretions and was most likely a crucial step towards establishing relations with social insects enhanced by chemical communication. In the Elateriformia, and rarely in other lineages, elytral loss is a consequence of paedomorphosis, related to a specific resource-allocation strategy. In many groups of beetles with reduced elytra, alternative defensive strategies can be found. This includes, for instance, aposematic coloration, chemical defence, mimicry or bioluminescence. Direct drivers of elytral loss in many groups remain unclear, and more studies are needed to understand the evolutionary background and implications of this significant morphological modification in Coleoptera.