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Species in the beetle family Histeridae exhibit numerous defensive adaptations, from a generally compact and spheroid body shape to retractable tarsi, legs, heads, and antennae. Modes of antennal concealment are particularly variable, underscoring the importance of protecting these essential sensory structures. Understanding the evolution of these morphological features has been hindered by a weak understanding of the family's basal phylogeny, and corresponding patterns of niche-use and morphological evolution. Cretaceous amber fossils have been proliferating, filling in important morphological gaps right around the time of the family's explosive radiation. Here we describe 10 new species from Cretaceous Burmese ambers, six of them representing new genera: Palaeabraeus glabrus gen. nov. et sp. nov. (Abraeinae); Pseudacritus extinctus gen. nov. et sp. nov. (Abraeinae); Miculissima excavata gen. nov. et sp. nov. (unplaced to subfamily); Placatister cascus gen. nov. et sp. nov. (unplaced to subfamily); Cretomalus tibiodentatus gen. nov. et sp. nov. (Dendrophilinae: Paromalini); Prodigister tricostatus gen. nov. et sp. nov. (unplaced to subfamily); Anapleus punctulatus sp. nov. (Dendrophilinae: Anapleini); Pantostictus hirsutus sp. nov. (Abraeinae: Pantostictini); Phasmister kraliceki sp. nov. (Onthophilinae); and Phasmister planatus sp. nov. (Onthophilinae). A revised phylogenetic analysis that includes these taxa supports previous hints that inquilinous forms were prevalent and diverse during the Cretaceous. These results also support the contention that pressures in these environments to protect the critically important sensory apparatus, the antenna, were strong, driving multiple origins of two of the more protective configurations among extant taxa. Some of the new genera remain unplaced to subfamily, underscoring the gaps that still remain in the early fossil record for the family, and the continued need for more comprehensive analyses of combined data from extant taxa, along with additional extinct forms that we may assume will continue to be discovered. [ABSTRACT FROM AUTHOR]

DNA-based studies have revealed that the terrestrial water scavenger beetle genus Cercyon Leach, 1817 (Coleoptera: Hydrophilidae: Sphaeridiinae: Megasternini) is polyphyletic, grouping similarly looking but unrelated species that were not assigned to other genera due to the absence of unusual morphological characters. In this study, we analyse the morphology, DNA data and species diversity of one of the Asian clades of ' Cercyon ' to test whether a natural, phylogeny-based generic classification can be established. We add DNA data (five nuclear and three mitochondrial fragments) for additional species and specimens of the clade to test its monophyly and reveal phylogenetic relationships among species. We perform a detailed morphological study of all species, including SEM micrographs, to reveal synapomorphies of the DNA-based clades. We demonstrate that the lineage, described here as Asiacyon Mai, Jia, Ryndevich & Fikáček, gen. nov., is strongly supported by DNA data, has limited distribution (eastern Asia), and its species share similar biology (inhabiting fresh or decaying plant tissues), though it can be only diagnosed by a combination of plesiomorphic characters. A detailed treatment is provided for the Chinese species, including species diagnoses, illustrations of habitus and male genitalia, (re)descriptions and a key to species. A total of 14 Chinese species are recognised, of which 11 are described as new: Asiacyon pax sp. nov. (Guangdong, Hong Kong, Hunan), A. pseudincretus sp. nov. (Anhui, Jiangxi, Taiwan, Zhejiang), A. vicincretus sp. nov. (Guangdong, Guangxi), A. zhengyucheni sp. nov. (Yunnan), A. huilanae sp. nov. (Yunnan), A. cornipenis sp. nov. (Yunnan), A. belousovi sp. nov. (Yunnan), A. liangchengi sp. nov. (Yunnan), A. paraequalis sp. nov. (Yunnan), A. pengzhongi sp. nov. (Hunan) and A. xiuzhenae sp. nov. (Hainan, Yunnan). Three Chinese species previously classified in Cercyon are transferred to Asiacyon : A. incretus (d'Orchymont, 1941), comb. nov., A. primoricus (Ryndevich & Prokin, 2017), comb. nov. (newly recorded from China) and A. indicus (d'Orchymont, 1926), comb. nov. (newly recorded from China and Laos). Additionally, seven Asian species previously classified in Cercyon are transferred to Asiacyon based on their external morphology, but not studied in detail: A. aequalis (Sharp, 1884), comb. nov., A. conjiciens (Walker, 1858), comb. nov., A. dilutus (Régimbart, 1903), comb. nov., A. placidus (Sharp, 1884), comb. nov., A. pseudodilutus (Satô, 1979), comb. nov., A. retius (Ryndevich & Prokin, 2017), comb. nov., and A. rubicundus (Sharp, 1884), comb. nov. In total, the genus now comprises 21 named species and several undescribed species from India, Myanmar and Indonesia. ZooBank: Morphology is not always a good indicator of biological diversity, aswe illustrate in Asian species classified under Cercyon , a genus of terrestrial water scavenger beetles. We describe Asiacyon gen. nov., which is strongly supported by DNA data, has limited distribution and unique habitat preferences, yet it highly resembles other unrelated ʻ Cercyon ʼ. The species diversity of this lineage was under-estimated: we describe 11 new species from China. We argue that ' Cercyon ' should be divided into DNA-based natural genera despite their morphological similarity. (Image credit: Martin Fikáček.) [ABSTRACT FROM AUTHOR]

South Pacific archipelagos are central in the biogeographic debate on the relative importance of vicariance and dispersal in shaping the distribution of species. However, each taxonomic group was subject to different processes and histories, and here, we reveal the historical biogeography of the diverse Eumolpinae leaf beetles, widely distributed in the region. Extensive taxon sampling focusing on South Pacific Eumolpinae was used to infer the first molecular phylogeny of the group using three single‐copy protein‐coding nuclear and two mitochondrial markers. Upon assessing the clade of interest for lineage‐specific variation in substitution rates, the age of the most recent common ancestors was estimated using out‐group calibration and multi‐gamma site models (MGSMs). Biogeographic analyses used standard event‐based inferences also incorporating phylogenetic uncertainty. Zealandian Eumolpinae are monophyletic and appear to have split from their global relatives in the transition from the Cretaceous to the Paleogene. Variation in the rates of molecular evolution affected the in‐group stem branch, with a significant drop in the substitution rate, and the MGSM correction recovered the crown age of Zealandian Eumolpinae during the Late Eocene–Oligocene transition. Biogeographic inference resolved the origin of the radiation in New Caledonia, favouring a null model without island age constraints, and repeated dispersal events to the other islands, including three independent but synchronous colonisations of New Zealand during the Miocene. New Caledonia, with a highly diverse Eumolpinae fauna of uncertain origin, acted as a hub and pump of biodiversity of these beetles in the entire South Pacific region, sending migrants to other islands through long‐distance dispersal with lineages establishing when land became available. [ABSTRACT FROM AUTHOR]

The turbulent Tertiary and Quaternary history of Europe and the Ponto-Caucasus has had a strong impact on its biota, resulting in unusual patterns of speciation, diversification, and dispersal. Our study reveals the Late-Tertiary diversification and biogeographic history of Mniophila , a Western Palaearctic endemic moss-inhabiting flightless flea beetle distributed across Europe and the Ponto-Caucasus. We assembled samples across the whole range of the genus except Crimea. Based on a molecular phylogenetic analysis, we found that the diversification of Mniophila started in the Balkan Peninsula, and was followed by at least two independent colonizations of other parts of Europe. The Ponto-Caucasian species are all descendants of a single colonization from the Balkans, followed by species' radiation. The Mniophila beetles are, therefore, one of the first-known cases of the colonization of the Caucasus from Europe. We integrated our DNA data with morphology, allowing us to uncover the cryptic diversity of Mniophila and to revise its European species. We describe Mniophila haveli sp. nov. from the Carpathians and Balkans, M. wroblewskii Wańkowicz, 1880 from Central Europe and the Balkans is restored as a valid species, and M. bosnica Apfelbeck, 1914 is newly recognized as a Dinaric endemic. We reveal an exceedingly large distribution range for M. muscorum (Koch, 1803), which is unusual for a flightless beetle. [ABSTRACT FROM AUTHOR]

Forest soil and leaf litter support diverse arthropod mesofauna for which diversity dynamics is challenging to study due to the high number of species and specimens, small body size and limited taxonomic knowledge.Immature stages (larvae) are even harder to identify than adults, as their morphology is largely unknown. Therefore, larvae are often ignored, even though they may form a substantial proportion of specimens collected, are less mobile than adults and their exclusion may provide an incomplete diversity profile.Here, we use Oxford Nanopore DNA barcoding to investigate whether the inclusion of larvae provides a more complete taxonomic, phylogenetic and functional diversity profiles in leaf litter beetles (Coleoptera) from a subtropical forest in Taiwan.Our results indicate that larvae represent up to 38% of beetle specimens per sample, but most of them belong to 2–3 common species. Larvae of most beetle species are rarely collected repeatedly or in multiple specimens, possibly due to special habitat requirements or high seasonality.Taxonomic, phylogenetic and incidence‐based functional diversity measures were not affected by the exclusion of larvae in the Staphylinidae dataset but were strongly biased in all‐beetle dataset, especially when only common or abundant species were considered. Taxonomic beta diversity was not affected by the omission of larvae.Our results indicate that immature stages may be omitted in ecological studies of arthropods in case both adults and larvae co‐occur in the same habitat, and the sites are sampled repeatedly. Caution is needed (1) in groups in which larvae and adults do not inhabit the same environment or strongly differ in biology, (2) when rare species are omitted or (3) when functional diversity is calculated from abundance data. [ABSTRACT FROM AUTHOR]