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Beetles (Coleoptera) are the most diverse and species-rich group of insects, and a robust, time-calibrated phylogeny is fundamental to understanding macroevolutionary processes that underlie their diversity. Here we infer the phylogeny and divergence times of all major lineages of Coleoptera by analyzing 95 protein-coding genes in 373 beetle species, including ~67% of the currently recognized families. The subordinal relationships are strongly supported as Polyphaga (Adephaga (Archostemata, Myxophaga)). The series and superfamilies of Polyphaga are mostly monophyletic. The species-poor Nosodendridae is robustly recovered in a novel position sister to Staphyliniformia, Bostrichiformia, and Cucujiformia. Our divergence time analyses suggest that the crown group of extant beetles occurred ~297 million years ago (Mya) and that ~64% of families originated in the Cretaceous. Most of the herbivorous families experienced a significant increase in diversification rate during the Cretaceous, thus suggesting that the rise of angiosperms in the Cretaceous may have been an ‘evolutionary impetus’ driving the hyperdiversity of herbivorous beetles. The phylogeny of beetles, which represent ~25% of known extant animal species, has been a challenge to resolve. Here, Zhang et al. infer a time-calibrated phylogeny for Coleoptera based on 95 protein-coding genes in 373 species and suggest an association between the hyperdiversification of beetles and the rise of angiosperms.

As major consumers of heterotrophic bacteria and phytoplankton, microzooplankton are a critical link in aquatic foodwebs. Here, we show that a major marine microflagellate grazer is infected by a giant virus, Cafeteria roenbergensis virus (CroV), which has the largest genome of any described marine virus (≈730 kb of double-stranded DNA). The central 618-kb coding part of this AT-rich genome contains 544 predicted protein-coding genes; putative early and late promoter motifs have been detected and assigned to 191 and 72 of them, respectively, and at least 274 genes were expressed during infection. The diverse coding potential of CroV includes predicted translation factors, DNA repair enzymes such as DNA mismatch repair protein MutS and two photolyases, multiple ubiquitin pathway components, four intein elements, and 22 tRNAs. Many genes including isoleucyl-tRNA synthetase, eIF-2γ, and an Elp3-like histone acetyltransferase are usually not found in viruses. We also discovered a 38-kb genomic region of putative bacterial origin, which encodes several predicted carbohydrate metabolizing enzymes, including an entire pathway for the biosynthesis of 3-deoxy-d-manno-octulosonate, a key component of the outer membrane in Gram-negative bacteria. Phylogenetic analysis indicates that CroV is a nucleocytoplasmic large DNA virus, with Acanthamoeba polyphaga mimivirus as its closest relative, although less than one-third of the genes of CroV have homologs in Mimivirus. CroV is a highly complex marine virus and the only virus studied in genetic detail that infects one of the major groups of predators in the oceans.

Large DNA viruses in the phylum Nucleocytoviricota, sometimes referred to as “giant viruses” owing to their large genomes and virions, have been the subject of burgeoning interest over the last decade. Here, we describe recently adopted taxonomic updates for giant viruses within the order Imitervirales. The families Allomimiviridae, Mesomimiviridae, and Schizomimiviridae have been created to accommodate the increasing diversity of mimivirus relatives that have sometimes been referred to in the literature as “extended Mimiviridae”. In addition, the subfamilies Aliimimivirinae, Megamimivirinae, and Klosneuvirinae have been established to refer to subgroups of the Mimiviridae. Binomial names have also been adopted for all recognized species in the order. For example, Acanthamoeba polyphaga mimivirus is now classified in the species Mimivirus bradfordmassiliense.

Key Points Acanthamoeba polyphaga mimivirus (APMV) and subsequently discovered giant viruses of amoebae challenge the previous definition of viruses and their classification. The replication cycle, structure, genomic make-up and plasticity of giant viruses differ from those of traditional viruses. They extend the definition of viruses into a broader range of biological entities, some of which are very simple and others of which have a complexity that is comparable to that of other microorganisms. Giant viruses of amoebae have virus particles as large as some microorganisms that are visible by light microscopy and that have a stunning level of complexity. Their genomes are mosaics and contain large repertoires of genes, some of which are hallmarks of cellular organisms, although the majority of which have unknown functions. Mimiviruses are associated with a specific mobilome and are parasitized by viruses that they can defend against. Several hypotheses on the ancient origin and evolutionary relationship between cellular organisms and giant viruses of amoebae have been proposed, and these topics continue to be debated. The detection of giant viruses of amoebae in humans and the study of their potential pathogenicity are emerging fields. The discovery of the giant amoebal virus mimivirus, in 2003, opened up a new area of virology. Extended studies, including those of mimiviruses, have since revealed that these viruses have genetic, proteomic and structural features that are more complex than those of conventional viruses. The accidental discovery of the giant virus of amoeba — Acanthamoeba polyphaga mimivirus (APMV; more commonly known as mimivirus) — in 2003 changed the field of virology. Viruses were previously defined by their submicroscopic size, which probably prevented the search for giant viruses, which are visible by light microscopy. Extended studies of giant viruses of amoebae revealed that they have genetic, proteomic and structural complexities that were not thought to exist among viruses and that are comparable to those of bacteria, archaea and small eukaryotes. The giant virus particles contain mRNA and more than 100 proteins, they have gene repertoires that are broader than those of other viruses and, notably, some encode translation components. The infection cycles of giant viruses of amoebae involve virus entry by amoebal phagocytosis and replication in viral factories. In addition, mimiviruses are infected by virophages, defend against them through the mimivirus virophage resistance element (MIMIVIRE) system and have a unique mobilome. Overall, giant viruses of amoebae, including mimiviruses, marseilleviruses, pandoraviruses, pithoviruses, faustoviruses and molliviruses, challenge the definition and classification of viruses, and have increasingly been detected in humans.

Poxviruses are considered to be unique among all DNA viruses, because their infection cycle is carried out exclusively in the host cytoplasm. Such an infection strategy is of interest, because it necessitates generation of elaborate factories in which viral replication and assembly are promoted. By using diverse imaging techniques, we show that the infection cycle of the largest virus currently identified, the Acanthamoeba polyphaga Mimivirus, similarly occurs exclusively in the host cytoplasm. We further show that newly synthesized mRNAs accumulate at discrete cytoplasmic sites that are distinct from the sites where viral replication occurs, and this is observed in vaccinia infection. By revealing substantial physiologic similarity between poxviruses and Mimivirus and thus, implying that an entirely cytoplasmic viral replication might be more common than generally considered, these findings underscore the ability of DNA viruses to generate large and elaborate replication factories.

BACKGROUND: The identification of novel giant viruses from the nucleocytoplasmic large DNA viruses group and their virophages has increased in the last decade and has helped to shed light on viral evolution. This study describe the discovery, isolation and characterization of Samba virus (SMBV), a novel giant virus belonging to the Mimivirus genus, which was isolated from the Negro River in the Brazilian Amazon. We also report the isolation of an SMBV-associated virophage named Rio Negro (RNV), which is the first Mimivirus virophage to be isolated in the Americas. METHODS/RESULTS: Based on a phylogenetic analysis, SMBV belongs to group A of the putative Megavirales order, possibly a new virus related to Acanthamoeba polyphaga mimivirus (APMV). SMBV is the largest virus isolated in Brazil, with an average particle diameter about 574 nm. The SMBV genome contains 938 ORFs, of which nine are ORFans. The 1,213.6 kb SMBV genome is one of the largest genome of any group A Mimivirus described to date. Electron microscopy showed RNV particle accumulation near SMBV and APMV factories resulting in the production of defective SMBV and APMV particles and decreasing the infectivity of these two viruses by several logs. CONCLUSION: This discovery expands our knowledge of Mimiviridae evolution and ecology.

The genus Bryaxis Kugelann (Goniaceritae: Bythinini) is the most species-rich genus of the subfamily Pselaphinae and is mainly distributed in the Palearctic region. Although previous studies have documented 14 species in the Korean Peninsula, the true diversity, ecology, and immature stages of the genus are still inadequately known. In this study, five new Korean species are described: B.grandinodussp. nov., B.uljinensissp. nov., B.fabaiformissp. nov., B.girinensissp. nov., and B.nemorosussp. nov. Illustrations of the habitus and other morphological details, and a distribution map are provided. In addition, Bryaxisleechanyoungi Nomura & Lee, 1993 is proposed as a new synonym of B.mahunkai Löbl, 1975 based on the original description and illustrations of diagnostic characters.The genus Bryaxis Kugelann (Goniaceritae: Bythinini) is the most species-rich genus of the subfamily Pselaphinae and is mainly distributed in the Palearctic region. Although previous studies have documented 14 species in the Korean Peninsula, the true diversity, ecology, and immature stages of the genus are still inadequately known. In this study, five new Korean species are described: B.grandinodussp. nov., B.uljinensissp. nov., B.fabaiformissp. nov., B.girinensissp. nov., and B.nemorosussp. nov. Illustrations of the habitus and other morphological details, and a distribution map are provided. In addition, Bryaxisleechanyoungi Nomura & Lee, 1993 is proposed as a new synonym of B.mahunkai Löbl, 1975 based on the original description and illustrations of diagnostic characters.

Two new species of Longitarsus Latreille, 1829 from China are described: L.pekingensis Liang, Konstantinov & Ge, sp. nov. (Beijing) and L.xinjiangensis Liang, Konstantinov & Ge, sp. nov. (Xinjiang). Images of dorsal and lateral habitus, pronotum, head, and male and female genitalia are provided. The records of Longitarsusviolentus Weise, 1893 and Longitarsusweisei Guillebeau, 1895 in China are discussed. Holotypes of L.marguzoricus Konstantinov in Konstantinov & Lopatin, 2000 and L.violentoides Konstantinov in Konstantinov & Lopatin, 2000 are illustrated with images of pronotum and median lobe of aedeagus. A key to species of L.violentus species group is provided.Two new species of Longitarsus Latreille, 1829 from China are described: L.pekingensis Liang, Konstantinov & Ge, sp. nov. (Beijing) and L.xinjiangensis Liang, Konstantinov & Ge, sp. nov. (Xinjiang). Images of dorsal and lateral habitus, pronotum, head, and male and female genitalia are provided. The records of Longitarsusviolentus Weise, 1893 and Longitarsusweisei Guillebeau, 1895 in China are discussed. Holotypes of L.marguzoricus Konstantinov in Konstantinov & Lopatin, 2000 and L.violentoides Konstantinov in Konstantinov & Lopatin, 2000 are illustrated with images of pronotum and median lobe of aedeagus. A key to species of L.violentus species group is provided.