Structure and bioactivity of an insecticidal trans-defensin from assassin bug venom.

Disulfide-rich peptides such as defensins play diverse roles in immunity and ion channel modulation, as well as constituting the bioactive components of many animal venoms. We investigated the structure and bioactivity of U-RDTX-Pp19, a peptide previously discovered in venom of the assassin bug Pristhesancus plagipennis. Recombinant Pp19 (rPp19) was found to possess insecticidal activity when injected into Drosophila melanogaster. A bioinformatic search revealed that domains homologous to Pp19 are produced by assassin bugs and diverse other arthropods. rPp19 co-eluted with native Pp19 isolated from P. plagipennis, which we found is more abundant in hemolymph than venom. We solved the three-dimensional structure of rPp19 using 2D 1H NMR spectroscopy, finding that it adopts a disulfide-stabilized structure highly similar to known trans-defensins, with the same cystine connectivity as human α-defensin (I-VI, II-IV, and III-V). The structure of Pp19 is unique among reported structures of arthropod peptides.

Chromosome-Aware Phylogenomics of Assassin Bugs (Hemiptera: Reduvioidea) Elucidates Ancient Gene Conflict.

Though the phylogenetic signal of loci on sex chromosomes can differ from those on autosomes, chromosomal-level genome assemblies for nonvertebrates are still relatively scarce and conservation of chromosomal gene content across deep phylogenetic scales has therefore remained largely unexplored. We here assemble a uniquely large and diverse set of samples (17 anchored hybrid enrichment, 24 RNA-seq, and 70 whole-genome sequencing samples of variable depth) for the medically important assassin bugs (Reduvioidea). We assess the performance of genes based on multiple features (e.g., nucleotide vs. amino acid, nuclear vs. mitochondrial, and autosomal vs. X chromosomal) and employ different methods (concatenation and coalescence analyses) to reconstruct the unresolved phylogeny of this diverse (∼7,000 spp.) and old (>180 Ma) group. Our results show that genes on the X chromosome are more likely to have discordant phylogenies than those on autosomes. We find that the X chromosome conflict is driven by high gene substitution rates that impact the accuracy of phylogenetic inference. However, gene tree clustering showed strong conflict even after discounting variable third codon positions. Alternative topologies were not particularly enriched for sex chromosome loci, but spread across the genome. We conclude that binning genes to autosomal or sex chromosomes may result in a more accurate picture of the complex evolutionary history of a clade.

Taxonomic revision of the Apiomerus maya species group (Heteroptera: Reduviidae: Harpactorinae).

The Apiomerus maya species group of the genus Apiomerus Hahn, 1831 (Hemiptera: Heteroptera: Reduviidae: Harpactorinae: Apiomerini), the bee assassins, is revised. Four species that are native to parts of Mexico and Central America are recognized and redescribed: Apiomerus maya Dispons, 1971, A. pipil Dispons, 1971, A. venosus Stl, 1872, and A. immundus Bergroth, 1898. Intraspecific polychromatism and male genital morphology are documented for the group. The taxonomy of two previously recognized species is updated: A. tristis Champion, 1899 syn. nov. is here synonymized with A. venosus and A. guatemalensis Dispons, 1971 syn. nov. with A. pipil.

Phylogenetic relationships and revised classification of the true bug infraorder Dipsocoromorpha (Insecta: Hemiptera: Heteroptera).

Currently comprising only about 430 species, Dipsocoromorpha or minute litter bugs are one of the small infraorders of Heteroptera. They are classified into five morphologically distinct families--Ceratocombidae, Dipsocoridae, Hypsipterygidae, Schizopteridae and Stemmocryptidae--but relationships among and within these families are poorly understood owing to the lack of phylogenetic studies. A phylogenetic hypothesis based on combined molecular and morphological data is important to both evaluate and revise the higher-level classification and to explore the evolutionary history of morphological features including elytriform (or beetle-like) forewings, that seem to have evolved multiple times in this group, jumping devices, and the highly modified and diverse male genitalia. We here use a dataset combining Sanger-derived (~4500 bp; 108 taxa) and Illumina-generated (~7500 bp; 24 taxa) sequence data with a morphological matrix (159 characters) and taxon sampling that comprises all currently recognized family-, subfamily- and tribal-level taxa and comprehensive genus-level sampling to investigate phylogenetic relationships within litter bugs. Our results support the monophyly of Dipsocoromorpha, Schizopteridae and Dipsocoridae, whereas Ceratocombidae and the schizopterine subfamily "Ogeriinae" are polyphyletic and paraphyletic, respectively. A new classification is proposed that recognizes six families, including Trichotonannidae, stat.n., and two subfamilies each within the two larger families Ceratocombidae and Schizopteridae. Ancestral state reconstructions outline the complex evolutionary history of many morphological characters, including 15 independent origins of elytriform forewings, and at least five shifts in the degree of genitalic asymmetry.

New alignment-based sequence extraction software (ALiBaSeq) and its utility for deep level phylogenetics.

Despite many bioinformatic solutions for analyzing sequencing data, few options exist for targeted sequence retrieval from whole genomic sequencing (WGS) data with the ultimate goal of generating a phylogeny. Available tools especially struggle at deep phylogenetic levels and necessitate amino-acid space searches, which may increase rates of false positive results. Many tools are also difficult to install and may lack adequate user resources. Here, we describe a program that uses freely available similarity search tools to find homologs in assembled WGS data with unparalleled freedom to modify parameters. We evaluate its performance compared to other commonly used bioinformatics tools on two divergent insect species (>200 My) for which annotated genomes exist, and on one large set each of highly conserved and more variable loci. Our software is capable of retrieving orthologs from well-curated or unannotated, low or high depth shotgun, and target capture assemblies as well or better than other software as assessed by recovering the most genes with maximal coverage and with a low rate of false positives throughout all datasets. When assessing this combination of criteria, ALiBaSeq is frequently the best evaluated tool for gathering the most comprehensive and accurate phylogenetic alignments on all types of data tested. The software (implemented in Python), tutorials, and manual are freely available at https://github.com/AlexKnyshov/alibaseq.

Taxonomic revision of emGuapinannus/em Wygodzinsky, 1951 (Hemiptera: Schizopteridae), with description of 19 new species.

Guapinannus Wygodzinsky, 1951 (Hemiptera: Schizopteridae) was described based on a single female specimen from Costa Rica. Some additional specimens representing this genus have since become available and were incorporated into a comparative male genitalic study across Dipsocoromorpha and into combined molecular and morphological hypotheses of the infraorder. However, the species-level diversity of Guapinannus has remained unexplored and undocumented. Based on examination of 264 specimens from central and South America, we here revise the taxonomy of Guapinannus, describing 19 species as new (Guapinannus anaticulus, sp. n.; Guapinannus artus, sp. n.; Guapinannus auriculus, sp. n.; Guapinannus castigatus, sp. n.; Guapinannus clava, sp. n.; Guapinannus dispar, sp. n.; Guapinannus falcis, sp. n.; Guapinannus graziae, sp. n.; Guapinannus minutus, sp. n.; Guapinannus orbiculatus, sp. n.; Guapinannus plurilobus, sp. n.; Guapinannus policis, sp. n.; Guapinannus robustus, sp. n.; Guapinannus sinuosus, sp. n.; Guapinannus tatumbia, sp. n.; Guapinannus tenuis, sp. n.; Guapinannus tergus, sp. n.; Guapinannus trilobus, sp. n.; Guapinannus uncus, sp. n.). In addition, we provide photos of the female holotype of Guapinannus bierigi Wygodzinsky, 1951, SEM documentation for Guapinannus clava, sp. n., habitus photos and a map for all species, and line drawings of male genitalic features for all species for which males are known.

Four new genera of Schizopteridae (Hemiptera: Heteroptera) from the Afrotropical and Neotropical regions.

Despite a recent surge of taxonomic work on the dipsocoromorphan family Schizopteridae, new genus-level taxa remain to be documented and described. The curation of Malaise and Yellow Pan Trap sample residues from Central and South America and Cameroon resulted in the discovery of five undescribed species that based on combined molecular and morphological phylogenetic analyses represent four phylogenetically isolated lineages within non-hypselosomatine Schizopteridae. To accommodate these new species, we here describe the four new genera Caucanannus gen. n. (Colombia, Ecuador, and Brazil) with Caucanannus perplexus sp. n. and Caucanannus novissimis sp. n.; Kamakonocoris gen. n. (Cameroon) with Kamakonocoris carinata sp. n.; Perittonannus gen. n. (Costa Rica) with Perittonannus antiquus sp. n.; and Rimanannus gen. n. (Cameroon) with Rimanannus camerunensis sp. n. The four genera are characterized by distinctive wing venation and male and female genitalic features. We provide habitus photographs and document morphological details using digital macrophotography as well as light compound microscopic and scanning electron microscopic images. Maps and measurements are also included.

Taxonomic revision of the New World big-eyed minute litter bug genus Ommatides Uhler (Hemiptera: Schizopteridae).

Hypselosomatinae, the big-eyed minute litter bugs, are diagnosed among Schizopteridae (infraorder Dipsocoromorpha) by the large eye, 4-segmented labium, and distinct wing venation. The group was recovered as sister taxon to all remaining Schizopteridae in recent molecular phylogenetic analyses. Described species diversity of Hypselosomatinae (13 extant genera prior to this study) is greatest in the Old World and in particular the Australian region, while only five monotypic or small genera are currently described from the New World (Glyptocombus Heidemann, Ommatides Uhler, Williamsocoris Carpintero Dellapé, Hypsohapsis Hoey-Chamberlain Weirauch, and Hypselosomops Hoey-Chamberlain Weirauch). Based on examination of 60 specimens of Hypselosomatinae from South America, we here synonymize Ommatides that includes one described species from the Lesser Antilles with the monotypic genus Williamsocoris Carpintero Dellapé from Argentina, describe seven new species of Ommatides (O. duodentis sp. nov., O. nudus sp. nov., O. parvidentis sp. nov., O. pillcopata sp. nov., O. pristis sp. nov., O. tridentis sp. nov., O. yoderi sp. nov. and O. zanderij sp. nov.) from various locations in South America, and redescribe Ommatides. We provide thorough documentation of morphological features using macroimages, SEM, and line drawings for new taxa and Ommatides insignis Uhler and a distribution map for all currently known New World Hypselosomatinae.

Revisiting habitat and lifestyle transitions in Heteroptera (Insecta: Hemiptera): insights from a combined morphological and molecular phylogeny.

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.

Insight from an ultraconserved element bait set designed for hemipteran phylogenetics integrated with genomic resources.

Target enrichment of conserved genomic regions facilitates collecting sequences of many orthologous loci from non-model organisms to address phylogenetic, phylogeographic, population genetic, and molecular evolution questions. Bait sets for sequence capture can simultaneously target thousands of loci, which opens new avenues of research on speciose groups. Current phylogenetic hypotheses on the >103,000 species of Hemiptera have failed to unambiguously resolve major nodes, suggesting that alternative datasets and more thorough taxon sampling may be required to resolve relationships. We use a recently designed ultraconserved element (UCE) bait set for Hemiptera, with a focus on the suborder Heteroptera, or the true bugs, to test previously proposed relationships. We present newly generated UCE data for 36 samples representing three suborders, all seven heteropteran infraorders, 23 families, and 34 genera of Hemiptera and one thysanopteran outgroup. To improve taxon sampling, we also mined additional UCE loci in silico from published hemipteran genomic and transcriptomic data. We obtained 2271 UCE loci for newly sequenced hemipteran taxa, ranging from 265 to 1696 (average 904) per sample. These were similar in number to the data mined from transcriptomes and genomes, but with fewer loci overall. The amount of missing data correlates with greater phylogenetic divergence from taxa used to design the baits. This bait set hybridizes to a wide range of hemipteran taxa and specimens of varying quality, including dried specimens as old as 1973. Our estimated phylogeny yielded topologies consistent with other studies for most nodes and was strongly-supported. We also demonstrate that UCE loci are almost exclusively from the transcribed portion of the genome, thus data can be successfully integrated with existing genomic and transcriptomic resources for more comprehensive phylogenetic sampling, an important feature in the era of phylogenomics. UCE approaches can be used by other researchers for additional studies on hemipteran evolution and other research that requires well resolved phylogenies.

Phylogenomics and the evolution of hemipteroid insects.

Hemipteroid insects (Paraneoptera), with over 10% of all known insect diversity, are a major component of terrestrial and aquatic ecosystems. Previous phylogenetic analyses have not consistently resolved the relationships among major hemipteroid lineages. We provide maximum likelihood-based phylogenomic analyses of a taxonomically comprehensive dataset comprising sequences of 2,395 single-copy, protein-coding genes for 193 samples of hemipteroid insects and outgroups. These analyses yield a well-supported phylogeny for hemipteroid insects. Monophyly of each of the three hemipteroid orders (Psocodea, Thysanoptera, and Hemiptera) is strongly supported, as are most relationships among suborders and families. Thysanoptera (thrips) is strongly supported as sister to Hemiptera. However, as in a recent large-scale analysis sampling all insect orders, trees from our data matrices support Psocodea (bark lice and parasitic lice) as the sister group to the holometabolous insects (those with complete metamorphosis). In contrast, four-cluster likelihood mapping of these data does not support this result. A molecular dating analysis using 23 fossil calibration points suggests hemipteroid insects began diversifying before the Carboniferous, over 365 million years ago. We also explore implications for understanding the timing of diversification, the evolution of morphological traits, and the evolution of mitochondrial genome organization. These results provide a phylogenetic framework for future studies of the group.

Synopsis of Schizopteridae (Hemiptera, Heteroptera, Dipsocoromorpha) from the United States, with description of seven new species from the US and Mexico.

Because species diversity of the small true bug family Schizopteridae is greatest in tropical and subtropical areas, it is not surprising that only four species have been described from the United States. As part of a larger project on the taxonomy and phylogenetics of Schizopteridae, 178 specimens from the United States were examined. This material contained representatives of the previously described species Glyptocombussaltator Heidemann, 1906, Corixideamajor McAtee & Malloch, 1925, Nannocorisarenarius Blatchley, 1926, and Schizopterabispina McAtee & Malloch, 1925, but also six undescribed species. These new taxa are described as Glyptocombushalbertae sp. n., Glyptocombussuteri sp. n., Nannocorisanophorus sp. n., Nannocorisbrevipilus sp. n., Schizoptera (Cantharocoris) rileyisp. n., and Schizoptera (Schizoptera) henryisp. n. Habitus images and genitalic illustrations of the previously described and the new species are provided as well as a map showing distribution ranges of these species in the United States and Mexico. To provide a comprehensive treatment of the small genus Glyptocombus Heidemann, 1906, Glyptocombusmexicanus sp. n. is also described that, to our knowledge, occurs only in Mexico, and the female of one additional undescribed Glyptocombus species is documented from Mexico.

Comparative morphology of male genitalic structures in the minute litter bugs Dipsocoromorpha (Insecta: Hemiptera: Heteroptera).

Insect male genitalia show an evolutionarily variable morphology that has proven to be valuable for both, species identifications and phylogenetic analyses at higher taxonomic levels. Accurate usage of genitalic characters in taxonomic descriptions and phylogenetic analyses depends on consistency of terminology and validity of homology hypotheses. Both areas are underdeveloped in many insect groups. We here document the morphology and advance homology hypotheses of male genitalic features for the hemipteran infraorder Dipsocoromorpha, the minute litter bugs. Genitalic structures and the pregenital abdomen in Dipsocoromorpha are strikingly modified and diverse compared to other Heteroptera. In addition to variation in the shape of phallic structures (parameres and aedeagus), minute litter bug genitalia vary in the direction and degree of asymmetry and feature a plethora of processes derived from various abdominal segments with significant variation at low taxonomic levels. Here, male genitalic structures for an extensive taxonomic sample (32 genera and 71 specimens) are documented using scanning electron and confocal microscopy, and a universal terminology for genitalic structures across minute litter bugs is established that will facilitate species discovery and evolutionary research. We conclude by proposing primary homology hypotheses across the infraorder that now can be tested in a phylogenetic framework.

Phylogenetic comparative analysis supports aposematic colouration-body size association in millipede assassins (Hemiptera: Reduviidae: Ectrichodiinae).

The diversity of colour patterns and its importance in interactions with the environment make colouration in animals an intriguing research focus. Aposematic colouration is positively correlated with body size in certain groups of animals, suggesting that warning colours are more effective or that crypsis is harder to achieve in larger animals. Surprisingly, this relationship has not been recovered in studies investigating insects, which may have been confounded by a focus on aposematic taxa that are also gregarious. Millipede assassin bugs (Hemiptera: Reduviidae: Ectrichodiinae) comprise species with cryptic and aposematic colour patterns across a range of body sizes, are typically solitary as adults and are thus an excellent model for investigating a possible association between colouration and body size. Here, we use a comprehensive phylogeny for Ectrichodiinae, ancestral state reconstruction of colouration, and phylogenetic comparative methods to test for a colouration-body size association. The ancestor of Ectrichodiinae is reconstructed as cryptically coloured, with multiple subsequent transitions between aposematic and cryptic colouration. Aposematic colouration is positively associated with male body length and supports the hypothesis that selection on Ectrichodiinae body size may influence evolutionary transitions between aposematic and cryptic colouration or alternatively that selection for aposematic colouration influences body size evolution.

Giant among dwarfs: Meganannus lewisi, gen. n. and sp. n., a new genus and species of minute litter bugs from Costa Rica (Hemiptera: Schizopteridae).

The Neotropical biodiversity of the cryptic and tiny minute litter bugs in the family Schizopteridae-although thought to be the best documented tropical fauna of Schizopteridae-is still poorly known. Sixteen species of Schizopteridae have been described from Costa Rica, 13 of which during the past few years, and the last new genus of Schizopteridae from that country was described more than half a century ago. We here describe and document a new monotypic genus of Schizopteridae from Costa Rica, Meganannus n. gen. The new genus belongs to the "Ogeriinae" + Schizopterinae lineage of Schizopteridae and stands out among other litter bugs by the large body size, among other features. We provide habitus photographs and document morphological details using scanning electron, confocal, and light compound microscopic images. A map and measurements are also produced. An illustrated identification key to genus groups and/or genera of Neotropical Schizopteridae including this new genus is presented.

Evolution, Systematics, and Biogeography of the Triatominae, Vectors of Chagas Disease.

In this chapter, we review and update current knowledge about the evolution, systematics, and biogeography of the Triatominae (Hemiptera: Reduviidae)-true bugs that feed primarily on vertebrate blood. In the Americas, triatomines are the vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. Despite declining incidence and prevalence, Chagas disease is still a major public health concern in Latin America. Triatomines occur also in the Old World, where vector-borne T. cruzi transmission has not been recorded. Triatomines evolved from predatory reduviid bugs, most likely in the New World, and diversified extensively across the Americas (including the Caribbean) and in parts of Asia and Oceania. Here, we first discuss our current understanding of how, how many times, and when the blood-feeding habit might have evolved among the Reduviidae. Then we present a summary of recent advances in the systematics of this diverse group of insects, with an emphasis on the contribution of molecular tools to the clarification of taxonomic controversies. Finally, and in the light of both up-to-date phylogenetic hypotheses and a thorough review of distribution records, we propose a global synthesis of the biogeography of the Triatominae. Over 130 triatomine species contribute to maintaining T. cruzi transmission among mammals (sometimes including humans) in almost every terrestrial ecoregion of the Americas. This means that Chagas disease will never be eradicated and underscores the fact that effective disease prevention will perforce require stronger, long-term vector control-surveillance systems.

Sylvatic host associations of Triatominae and implications for Chagas disease reservoirs: a review and new host records based on archival specimens.

BACKGROUND: The 152 extant species of kissing bug include important vectors of the debilitating, chronic, and often fatal Chagas disease, which affects several million people mainly in Central and South America. An understanding of the natural hosts of this speciose group of blood-feeding insects has and will continue to aid ongoing efforts to impede the spread of Chagas disease. However, information on kissing bug biology is piecemeal and scattered, developed using methods with varying levels of accuracy over more than 100 years. Existing host records are heavily biased towards well-studied primary vector species and are derived from primarily three different types of observations, associational, immunological or DNA-based, with varying reliability. METHODS: We gather a comprehensive and unparalleled number of sources reporting host associations via rigorous targeted searches of publication databases to review all known natural, or sylvatic, host records including information on how each record was collected. We integrate this information with novel host records obtained via attempted amplification and sequencing of a ∼160 base pair (bp) region of the vertebrate 12S mitochondrial gene from the gastrointestinal tract of 64 archival specimens of Triatominae representing 19 species collected primarily in sylvatic habitats throughout the southern United States and Central and South America during the past 10 years. We show the utility of this method for uncovering novel and under-studied groups of Triatominae hosts, as well as detecting the presence of the Chagas disease pathogen via Polymerase Chain Reaction (PCR) of a ∼400 bp sequence of the trypanosome 18S gene. RESULTS: New host associations for several groups of arboreal mammals were determined including sloths, New World monkeys, coatis, arboreal porcupines and, for the first time as a host of any Triatominae, tayras. A thorough review of previously documented sylvatic hosts, organized by triatomine species and the type of observation (associational, antibody-based, or DNA-based), is presented in a phylogenetic context and highlights large gaps in our knowledge of Triatominae biology. CONCLUSION: The application of DNA-based methods of host identification towards additional species of Triatominae, including rarely collected species that may require use of archival specimens, is the most efficient and promising way to resolve recognized shortfalls.

Molecular phylogenetics and biogeography of the ambush bugs (Hemiptera: Reduviidae: Phymatinae).

The ambush bugs (Heteroptera: Reduviidae: Phymatinae) are a diverse clade of predators known for their cryptic hunting behavior and morphologically diverse raptorial forelegs. Despite their striking appearance, role as pollinator predators, and intriguing biogeographic distribution, phylogenetic relationships within Phymatinae are largely unknown and the evolutionary history of the subfamily has remained in the dark. We here utilize the most extensive molecular phylogeny of ambush bugs to date, generated from a 3328 base pair molecular dataset, to refine our understanding of phymatine relationships, estimate dates of divergence (BEAST 2), and uncover historical biogeographic patterns (S-DIVA and DEC). This taxon set (39 species of Phymatinae and six outgroups) allowed reevaluation of the proposed sister group of Phymatinae and tribal-level relationships within the group, and for the first time proposes species-level relationships within Phymata Latreille, the largest genus of ambush bugs (∼109spp.). Available evidence suggests that Phymata originated in the Neotropical region, with subsequent dispersals to the Nearctic and Palearctic regions. This study provides a framework for future research investigating the evolutionary history of ambush bugs, as well as ecological and microevolutionary investigations.

Areas of endemism in the Nearctic: a case study of 1339 species of Miridae (Insecta: Hemiptera) and their plant hosts.

Areas of endemism are essential first hypotheses in investigating historical biogeography, but there is a surprising paucity of such hypotheses for the Nearctic region. Miridae, the plant bugs, are an excellent taxon to study in this context, because this group combines high species diversity, often small distribution ranges, a history of modern taxonomic revisions, and comprehensive electronic data capture and data cleaning that have resulted in an exceptionally error-free geospatial data set. Many Miridae are phytophagous and feed on only one or a small number of host plant species. The programs ndm/vndm are here used on plant bug and plant data sets to address two main objectives: (i) identify areas of endemism for plant bugs based on parameters used in a recent study that focused on Nearctic mammals; and (ii) discuss hypotheses on areas of endemism based on plant bug distributions in the context of areas identified by their host plant species. Given the narrow distribution ranges of many species of Miridae, the analytical results allow for tests of the prediction that areas of endemism for Miridae are smaller and more numerous, especially in the Western Nearctic, than are those of their host plants. Analyses of the default plant bug data set resulted in 45 areas of endemism, 35 of them north of Mexico and many located in the Western Nearctic; areas in the Nearctic are more numerous and smaller than those identified by mammals. The host plant data set resulted in ten areas of endemism, and even though the size range of areas is similar between the Miridae and plant data sets, the average area size is smaller in the Miridae data set. These results allow for the conclusion that the Miridae indeed present a valuable model system to investigate areas of endemism in the Nearctic.

Scratching the surface? Taxonomic revision of the subgenus Schizoptera (Odontorhagus) reveals vast undocumented biodiversity in the largest litter bug genus Schizoptera Fieber (Hemiptera: Dipsocoromorpha).

Schizoptera Fieber, currently the largest genus of litter bugs (Hemiptera: Dipsocoromorpha), comprises 61 extant species in 4 subgenera. Specimens are abundant in New World bulk and residue samples. Schizoptera species showcase stunning morphology including intricate, asymmetrical genitalia in males that have proven to provide excellent species diagnostic features in the past. Recent bulk sample sorting efforts have revealed a vast number of Schizoptera specimens from across the New World, with the majority representing undescribed species. We here taxonomically revise the subgenus Schizoptera (Odontorhagus) that has recently been shown to form a monophyletic group within Schizoptera. Characterized by the blunt tooth on the posterior margin of the propleuron, Schizoptera (Odontorhagus) previously comprised 10 species from Central and the northern part of South America. We here describe 20 new species in S. (Odontorhagus): S. acuta, n. sp., S. angularis, n. sp., S. ansata, n. sp., S. aspera, n. sp., S. brevis, n. sp., S. dentata, n. sp., S. dolosa, n. sp., S. enigmatica, n. sp., S. exacta, n. sp., S. gorgonensis, n. sp., S. insidiosa, n. sp., S. monstrosa, n. sp., S. piscicaudata, n. sp., S. quasicompleta, n. sp., S. radicata, n. sp., S. serrata, n. sp., S. simpla, n. sp., S. singularis, n. sp., S. trivialis, n. sp., S. ungulata, n. sp., increasing the species count of Schizoptera to 81. We provide morphological documentation including digital habitus images and genitalic drawings for all new species and document and redescribe existing species where feasible. Distribution maps and a key to the species of Schizoptera (Odontorhagus) are also presented. We predict that similar increases in species numbers are to be expected for the remaining subgenera of Schizoptera, making this genus a very diverse lineage of minute litter bugs.