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.

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.

A taxonomic revision of the genus Platycranus Fieber, 1870 (Hemiptera: Heteroptera: Miridae: Orthotylinae).

The Mediterranean orthotyline genus Platycranus is revised. Updated diagnoses and descriptions, data on distribution and hosts are provided for the genus and included species, and a key is presented to facilitate identification of species. Pictures of the dorsal habitus, scanning electron micrographs, and figures of genital structures are given. The following new synonymies are established: P. putoni Reuter, 1879 = P. eckerleini Wagner, 1962 = P. jordanicus Linnavuori, 1984; P. metriorrhynchus Reuter 1883 = P. longicornis Wagner, 1955 = P. rumelicus Simov, 2006; P. remanei Wagner, 1955 = P. minutus Wagner, 1955 = P. orientalis Linnavuori, 1965 = P. jurineae Putshkov, 1985 = P. boreae Gogala, 2002. P. erberi Fieber, 1870 is for the first time reported from Syria, and P. remanei is reported as new to Portugal.

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.

Voragocoris weirauchae sp. n. (Heteroptera: Schizopteridae: Schizopterinae), a further minute litter bug species from Brazil.

The genus Voragocoris Weirauch, 2012 is composed of Voragocoris schuhi Weirauch, 2012 and Voragocoris amrishi Makhan, 2013, previously recorded from Peru and Suriname, respectively. In this paper, a new species, Voragocoris weirauchae sp.n., is described based on specimens collected in the Brazilian Amazon, representing the first record of the genus from Brazil. We provide diagnosis, description, photographs of habitus, and scanning electron micrographs of the diagnostic features. A key to species based on males of Voragocoris is also presented.

Hoplonannus australis sp. nov. (Hemiptera, Schizopteridae): amended diagnosis of the genus and first record from South America.

Hoplonannus McAtee Maloch, 1925 comprises three species described from Central America. Females of all these species are known only from brachypterous specimens. This paper describes the first South American species of the genus, Hoplonannus australis sp. nov. The new species differs from its congeners, in females, by the submacroptery, presence of ocelli and a basal bulge in the seventh sternite; in males, it differs by the presence of a process in the eighth tergite and the right paramere bifurcate apically, with branches subparallel. These traits entail a new diagnosis for the genus.

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.

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.

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.

Chemically Mediated Arrestment of the Bed Bug, Cimex lectularius, by Volatiles Associated with Exuviae of Conspecifics.

Extracts of the exuviae (cast skins) of nymphal bed bugs (Cimex lectularius) were analyzed for volatile compounds that might contribute to arrestment of adult bed bugs. Four volatile aldehydes, (E)-2-hexenal, 4-oxo-(E)-2-hexenal, (E)-2-octenal, and 4-oxo-(E)-2-octenal were consistently detected in the headspace of freshly shed exuviae regardless of the developmental stages from which the exuviae were obtained. Quantification of the aldehydes in the solvent extracts of homogenized fresh, 45- or 99-d aged 5th instar exuviae indicated that the aldehydes are present in the exuviae and dissipate over time, through evaporation or degradation. Microscopic observation of the fifth instar exuviae indicated that the dorsal abdominal glands on the exuviae maintained their pocket-like structures with gland reservoirs, within which the aldehydes might be retained. Two-choice olfactometer studies with the volatiles from exuviae or a synthetic blend mimicking the volatiles indicated that adult bed bugs tend to settle close to sources of the aldehydes. Our results imply that the presence and accumulation of bed bug exuviae and the aldehydes volatilizing from the exuviae might mediate bed bugs' interaction with their microhabitats.