Assassin bugs are one of the most successful clades of predatory animals based on their species numbers (∼6,800 spp.) and wide distribution in terrestrial ecosystems. Various novel prey capture ...strategies and remarkable prey specializations contribute to their appeal as a model to study evolutionary pathways involved in predation. Here, we reconstruct the most comprehensive reduviid phylogeny (178 taxa, 18 subfamilies) to date based on molecular data (5 markers). This phylogeny tests current hypotheses on reduviid relationships emphasizing the polyphyletic Reduviinae and the blood-feeding, disease-vectoring Triatominae, and allows us, for the first time in assassin bugs, to reconstruct ancestral states of prey associations and microhabitats. Using a fossil-calibrated molecular tree, we estimated divergence times for key events in the evolutionary history of Reduviidae. Our results indicate that the polyphyletic Reduviinae fall into 11-14 separate clades. Triatominae are paraphyletic with respect to the reduviine genus Opisthacidius in the maximum likelihood analyses; this result is in contrast to prior hypotheses that found Triatominae to be monophyletic or polyphyletic and may be due to the more comprehensive taxon and character sampling in this study. The evolution of blood-feeding may thus have occurred once or twice independently among predatory assassin bugs. All prey specialists evolved from generalist ancestors, with multiple evolutionary origins of termite and ant specializations. A bark-associated life style on tree trunks is ancestral for most of the lineages of Higher Reduviidae; living on foliage has evolved at least six times independently. Reduviidae originated in the Middle Jurassic (178 Ma), but significant lineage diversification only began in the Late Cretaceous (97 Ma). The integration of molecular phylogenetics with fossil and life history data as presented in this paper provides insights into the evolutionary history of reduviids and clears the way for in-depth evolutionary hypothesis testing in one of the most speciose clades of predators.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Heteroptera, or true bugs, are part of the most successful radiation of nonholometabolous insects. Twenty-five years after the first review on the influence of cladistics on systematic research in ...Heteroptera, we summarize progress, problems, and future directions in the field. The few hypotheses on infraordinal relationships conflict on crucial points. Understanding relationships within Gerromorpha, Nepomorpha, Leptopodomorpha, Cimicomorpha, and Pentatomomorpha is improving, but progress within Enicocephalomorpha and Dipsocoromorpha is lagging behind. Nonetheless, the classifications of several superfamily-level taxa within the Pentatomomorpha, such as Aradoidea, Coreoidea, and Pyrrhocoroidea, are still unaffected by cladistic studies. Progress in comparative morphology is slow and drastically impedes our understanding of the evolution of major clades. Molecular systematics has dramatically contributed to accelerating the generation and testing of hypotheses. Given the fascinating natural history of true bugs and their status as model organisms for evolutionary studies, integration of cladistic analyses in a broader biogeographic and evolutionary context deserves increased attention.
Heteroptera, the true bugs, are part of the largest clade of non‐holometabolous insects, the Hemiptera, and include > 42 000 described species in about 90 families. Despite progress in resolving ...phylogenetic relationships between and within infraorders since the first combined morphological and molecular analysis published in 1993 (29 taxa, 669 bp, 31 morphological characters), recent hypotheses have relied entirely on molecular data. Weakly supported nodes along the backbone of Heteroptera made these published phylogenies unsuitable for investigations into the evolution of habitats and lifestyles across true bugs. Here we present the first combined morphological and molecular analyses of Heteroptera since 1993, using 135 taxa in 60 families, 4018 aligned bp of ribosomal DNA and 81 morphological characters, and various analytical approaches. The sister‐group relationship of the predominantly aquatic Nepomorpha with all remaining Heteroptera is supported in all analyses, and a clade formed by Enicocephalomorpha, Dipsocoromorpha and Gerromorpha in some. All analyses recover Leptopodomorpha + (Cimicomorpha + Pentatomomorpha), mostly with high support. Parsimony‐ and likelihood‐based ancestral state reconstructions of habitats and lifestyles on the combined likelihood phylogeny provide new insights into the evolution of true bugs. The results indicate that aquatic and semi‐aquatic true bugs invaded these habitats three times independently from terrestrial habitats in contrast to a recent hypothesis. They further suggest that the most recent common ancestor of Heteroptera was predacious, and that the two large predominantly phytophagous clades (Trichophora and Miroidea) are likely to have derived independently from predatory ancestors. We conclude that by combining morphological and molecular data and employing various analytical methods our analyses have converged on a relatively well‐supported hypothesis of heteropteran infraordinal relationships that now requires further testing using phylogenomic and more extensive morphological datasets.
The insect order Hemiptera, one of the best-studied insect lineages with respect to bacterial symbioses, still contains major branches that lack comprehensive characterization of associated bacterial ...symbionts. The Pyrrhocoroidea (Largidae 220 species and Pyrrhocoridae ∼300 species) is a clade of the hemipteran infraorder Pentatomomorpha. Studies on bacterial symbionts of this group have focused on members of Pyrrhocoridae, but recent examination of species of two genera of Largidae demonstrated divergent symbiotic complexes in these putative sister families. We surveyed the associated bacterial diversity of this group using paired-end Illumina sequencing and targeted Sanger sequencing of bacterial 16S rRNA amplicons of 30 pyrrhocoroid taxa, including 17 species of Largidae, in order to determine bacterial associates and the similarity of associated microbial communities among species. We also used molecular data (4,800 bp in 5 loci, for 57 ingroup and 12 outgroup taxa) to infer a phylogeny of the host superfamily, in order to trace the evolution of symbiotic complexes among Pentatomomorpha species. We undertook multiple lines of investigation (i.e., experimental rearing, fluorescence in situ hybridization microscopy, and phylogenetic and coevolutionary analyses) to elucidate potential transmission routes for largid symbionts. We found a prevalent and specific association of Largidae with Burkholderia strains of the plant-associated beneficial and environmental clade, housed in midgut tubules. As in other distantly related Heteroptera, symbiotic bacteria seem to be acquired from the environment every generation. We review the current understanding of symbiotic complexes within Pentatomomorpha and discuss means to further investigate the evolution and function of these symbioses.
Obligate symbioses with bacteria are common in insects, particularly Hemiptera, in which various forms of symbiosis occur. However, knowledge regarding symbionts remains incomplete for major hemipteran lineages. Thus, an accurate understanding of how these partnerships evolved and changed over millions of years is not yet achievable. We contribute to our understanding of the evolution of symbiotic complexes in Hemiptera by characterizing bacterial associates of Pyrrhocoroidea, focusing on the family Largidae. Members of Largidae are associated with specific symbiotic Burkholderia strains from a different clade than Burkholderia symbionts in other Burkholderia-associated Hemiptera. Evidence suggests that species of Largidae reacquire specific symbiotic bacteria from the environment every generation, which is a rare strategy for insects, with potentially volatile evolutionary ramifications, but one that must have persisted in Largidae and related lineages since their origin in the Cretaceous Period.
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•Phylogeny and biogeographic history of Madagascan Ectrichodiinae are investigated.•Molecular and morphological results indicate a non-monophyletic Madagascan fauna.•Two dispersals ...from Oriental areas and one from Africa to Madagascar are inferred.•DIVA and DEC+j, but not DEC, infer an out-of-Madagascar dispersal event to Africa.•Combined morphological-molecular phylogeny is used to inform taxonomic diagnoses.
For at least the past 80my, Madagascar, a major biodiversity hotspot, has been isolated from all other landmasses. This long-term isolation, along with geologic and climatic factors within Madagascar and throughout the Indian Ocean, has undoubtedly influenced the evolution of the island’s biota. However, few systematic analyses incorporating modern divergence dating and biogeographic analyses have focused on Madagascan insects. The diverse Madagascan millipede assassin bugs (Heteroptera: Reduviidae: Ectrichodiinae) offer an opportunity to contribute to a limited body of insect-related research that explores Madagascar’s historical biogeography. A molecular dataset (COI mtDNA and 18S, 28S D2 and D3–D5 rDNAs) for 56 taxa (39 ingroup) and a combined morphological (145 characters) and molecular dataset for 110 taxa (93 ingroup) are analyzed with maximum likelihood (ML) and parsimony approaches. Based on the molecular ML phylogeny, divergence times were estimated using fossil and secondary calibrations and biogeographic analyses performed using DIVA, DEC, and DEC+j models to determine the role and patterns of vicariance and dispersal in the origin of Madagascan Ectrichodiinae. Results indicate that Ectrichodiinae in Madagascar do not form a monophyletic group, different clades are closely related to Afrotropical and Oriental lineages, and have colonized the island via transoceanic dispersal at least twice from the Oriental region and once from the Afrotropical region in the last ∼68my. Additionally, the DEC+j and DIVA models infer a single out-of-Madagascar dispersal event to the Afrotropical region. Oceanic and geologic factors that may have facilitated dispersal between these three regions are discussed. Results of the combined analyses are used to explore character support for Madagascan taxa and inform taxonomic diagnoses. Our results are congruent with the small but growing body of biogeographic research supporting Cenozoic transoceanic dispersal for Madagascan invertebrates to and from Oriental and Afrotropical regions.
The assassin bug genus Koenigsbergia Popov, 2003 is currently monotypic and represented by a female holotype from Baltic Amber (~33.9–55.8 MYA). The genus was originally described within Phymatinae ...(Phymatine Complex or phymatine clade). However, our literature review reveals that the amber fossil likely belongs to the subfamily Phimophorinae, which is distantly related to the phymatine clade. The recent acquisition of one male and one nymph of Koenigsbergia provides the opportunity to reevaluate the systematic placement of this genus. We here examine the new fossils, concluding that the adult male represents an undescribed species, and describe it as Koenigsbergia explicativa , new species. Our morphological comparison between Phimophorinae, Phymatinae, and Koenigsbergia (macro imagining, scanning electron microscopy) shows that the fossil genus shares notable similarities with Phimophorus Bergroth, 1886 and Mendanocoris Miller, 1956. We therefore formally transfer the fossil genus to Phimophorinae.
Species in the heteropteran infraorder Dipsocoromorpha, or litter bugs, are small, cryptic, stunningly diverse and understudied. In addition to the vast amount of species discovery and morphological ...exploration that remain to be done in this group, phylogenetic relationships within the litter bugs are poorly understood. A phylogenetic framework will make Dipsocoromorpha more accessible for systematic studies at all levels and is therefore a first step towards a comprehensive treatment of the group. Using a molecular dataset (87 taxa of Hemiptera including 35 Dipsocoromorpha; two genes) and maximum likelihood and parsimony methods, we here aim to test, for the first time using cladistic methods and a comprehensive dataset, relationships within Dipsocoromorpha. We investigate if Dipsocoromorpha are monophyletic, shed light on the relationships among the three families included in this analysis, and study relationships within the largest family of Dipsocoromorpha, the Schizopteridae. Based on this dataset, we find that the monophyly of Dipsocoromorpha is strongly supported in all analyses and that Ceratocombidae and Dipsocoridae together are recovered as the sister group of Schizopteridae. Within Schizopteridae, Hypselosomatinae are treated as the sister group to a clade formed by the monophyletic Ogeriinae and monophyletic Schizopterinae. Within Schizopterinae, there is evidence for the monophyly of the Corixidea genus group, and we present additional infra-generic and genus-level hypotheses. We discuss these hypotheses in the light of current classifications and hypotheses on relationships and as the first contribution towards revealing the phylogenetic relationships of a remarkable and neglected clade of true bugs.
Although they are a valuable source of specimens, insect natural history collections continue to be under‐utilized in molecular systematics, mostly due to difficulties in obtaining DNA sequences. Old ...specimens or specimens stored under suboptimal conditions are intractable for traditional Sanger sequencing. In this study we use an inexpensive hybrid capture with in‐house generated baits to retrieve commonly utilized ribosomal and mitochondrial loci from old museum specimens and combine them with a Sanger‐generated dataset comprising recently collected material. We focus on the Corixidea genus group (Schizopteridae), which comprises rarely collected, small (1–2 mm) and primarily tropical insects of which only c. 10–20% of the species have been described. A molecular phylogeny is needed to resolve relationships and revise the genus‐level classification to correctly place the c. 150 yet to be described species. Applying this approach, we constructed a dataset, containing 101 taxa, 11 of which were preserved in low‐percentage ethanol, 48 are dry and point‐mounted, and 40 are > 20 years old at DNA extraction. The obtained data proved sufficient for reconstructing a well‐supported phylogeny with c. 50% of the predicted diversity, and for the oldest successfully sequenced specimen (95 years) to be unambiguously placed in that phylogeny. We confirmed monophyly of the Corixidea genus group, showed paraphyly of the genus Corixidea, and recovered nine well‐supported clades within the group. Ancestral character states of selected morphological features were inferred and used to re‐examine primary homology hypotheses and inform an upcoming taxonomic revision.
We utilized a cost‐efficient hybrid enrichment approach to obtain sequence data for low‐quality samples, including specimens collected during the 1920s–1970s, and sampled half of the estimated species‐level diversity of the group.
We confirmed monophyly of the Corixidea genus group, but refuted monophyly of the genus Corixidea and detected nine well‐supported clades, including four previously unknown lineages.
Using ancestral state reconstruction of several putatively genus‐diagnostic features, we tested primary homology hypotheses and shaped the genus‐level classification of the group for an upcoming taxonomic revision.
Gathering genetic data for rare species is one of the biggest remaining obstacles in modern phylogenetics, particularly for megadiverse groups such as arthropods. Next generation sequencing ...techniques allow for sequencing of short DNA fragments contained in preserved specimens >20 years old, but approaches such as whole‐genome sequencing are often too expensive for projects including many taxa. Several methods of reduced representation sequencing have been proposed that lower the cost of sequencing per specimen, but many remain costly because they involve synthesizing nucleotide probes and target hundreds of loci. These datasets are also frequently unique for each project and thus generally incompatible with other similar datasets.
Here, we explore utilization of in‐house generated DNA baits to capture commonly utilized mitochondrial and ribosomal DNA loci from insect museum specimens of various ages and preservation types without the a priori need to know the sequence of the target loci. Both within species and cross‐species capture are explored, on preserved specimens ranging in age from one to 54 years old.
We found most samples produced sufficient amounts of data to assemble the nuclear ribosomal rRNA genes and near complete mitochondrial genomes and produce well‐resolved phylogenies in line with expected results. The dataset obtained can be straightforwardly combined with the large cache of existing Sanger‐sequencing‐generated data built up over the past 30 years and targeted loci can be easily modified to those commonly used in different taxa. Furthermore, the protocol we describe allows for inexpensive data generation (as low as ~$35/sample), of at least 20 kilobases per specimen, for specimens at least as old as ~1965, and can be easily conducted in most laboratories.
If widely applied, this technique will accelerate the accurate resolution of the Tree of Life especially on non‐model organisms with limited existing genomic resources.
A phylogenetic analysis for the Cimicomorpha was conducted using 92 taxa, including eight outgroups and six species of Thaumastocoridae. Density of taxon sampling allows for tests of relationships at ...the family level for most taxa, whereas in the Miridae denser sampling allows for doing so on the tribal level. This level of sampling also corresponds with the availability of testable published hypotheses of relationships. Morphological data for 73 characters are coded for all taxa. Approximately 3500 base pairs of DNA were sequenced for the following gene regions for 83 taxa: 16S rDNA, 18S rDNA, 28S rDNA and COI. Results are presented for analysis of morphological data, individual molecular partitions, combined molecular data, combined morphological and molecular data for 83 taxa and combined morphological and molecular data for 92 taxa. Analyses of morphological data were performed using the parsimony programs nona and piwe: molecular and combined data were analysed using direct optimization with the program poy. Major conclusions of the present study include recognition of the following monophyletic groups: The Geocorisae is a monophyletic group. The monophyly of the Cimicomorpha – including Thaumastocoridae – is not supported in most analyses. The Reduviidae is monophyletic, with the Phymatinae Complex being the sister‐group of the remaining subfamilies. The circumscription of the Cimiciformes is altered from the prior conception of Schuh and Štys to also include the Joppeicidae, Microphysidae and Velocipedidae, as well as the recently described family Curaliidae; the monophyly of the Cimiciformes is supported in most analyses; the Cimiciformes is treated as the sister‐group of the Miroidea in most analyses. The monophyly of the Cimicoidea, including Curaliidae, is supported in all analyses including molecular data, whereas Curaliidae is treated as a more basal cimiciform in all other analyses. The monophyly and placement of the Thaumastocoridae is ambiguous across the range of analyses, and the monophyly of the Miroidea sensu Schuh and Štys receives limited support in the combined analyses of morphology + molecular data. The Tingidae and Miridae are each monophyletic and together almost invariably form a monophyletic group. Within the Miridae, several inclusive monophyletic groups at the subfamily/tribal level are more or less consistently recognized when molecular data are included; however, the interrelationships of the subfamilies vary substantially across the range of analyses. Of the individual molecular partitions, only 18S rDNA shows significant congruence with combined analyses of morphological, combined molecular or combined morphological and molecular data. Scenarios are discussed for the evolution of the metathoracic scent‐efferent system and the origin of the fossula spongiosa.
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