Wing-dimorphic insects occur in diverse habitats in heterogeneous environments. However, little is known about the wing dimorphism of insects that inhabit floodplains and the possible environmental factors affecting their wing morphs. In this study, we used cantharidin-baited traps to collect and quantify the psammobiont beetle Mecynotarsus niponicus Lewis, 1895 (Anthicidae) in a sandy floodplain of the Tamagawa River, Japan, in a one-year repeated cross-sectional study design. Our analysis of the demographic characteristics of over 400 M. niponicus adults and public weather-related data showed that: 1) two distinct wing morphs, long-winged (macropterous) and short-winged (brachypterous) individuals, were present within the population; 2) macroptery rates were consistently lower but varied greatly (6.7–50.0%) within a year; and 3) higher macroptery was significantly associated with greater fluctuation in river water level, namely flooding (odds ratio, 2.96; 95% confidence interval, 1.78–4.91; P < 0.001). Thus, the macropterous form of M. niponicus may be advantageous in avoiding temporal habitat loss due to river flooding. These observations may represent a first step toward testing a flooding-dispersal hypothesis for the morph alteration of wing-dimorphic insects in floodplains.

This review of the ground beetle genus Selenophorus Dejean of the Nearctic Region north of Mexico supplements the taxonomy and biogeography reported in an earlier catalogue on the North American Geadephaga. Eight new species of Selenophorus are described, seven Nearctic and one Neotropical. Selenophorus pararuficollis Messer and Raber, new species in South America and Selenophorus neoruficollis Messer and Raber, new species in southern United States join Neotropical Selenophorus ruficollis (Putzeys) in the previously monobasic S. ruficollis species group of subgenus Selenophorus. Also added to subgenus Selenophorus are Selenophorus undatus Messer and Raber, new species, S. opalinus species group; Selenophorus elytrostictus Messer and Raber, new species, S. striatopunctatus species group; Selenophorus balli Messer and Raber, new species, S. hylacis species group; Selenophorus rileyi Messer and Raber, new species, S. palliatus species group. Added to subgenus Celiamorphus Casey are Selenophorus nonellipticus Messer and Raber, new species, S. ellipticus species group; Selenophorus pumilus Messer and Raber, new species, S. pumilus species group. Thirteen new synonyms are proposed: Selenophorus municeps (Casey) with Selenophorus ellipticus Dejean; Selenophorus adjunctus (Casey), Selenophorus nanulus (Casey), and Selenophorus subtropicus (Casey) with Selenophorus granarius Dejean; Selenophorus elongatus (LeConte) with Selenophorus hylacis (Say); Selenophorus scolopaceus Casey with Selenophorus aeneopiceus Casey; Selenophorus cupreolus Casey, Selenophorus houstoni Casey, Selenophorus implicans Casey, and Selenophorus riparius Casey with Selenophorus pedicularius Casey; Selenophorus otiosus Casey with Selenophorus planipennis LeConte; Selenophorus laesus (LeConte) with Selenophorus palliatus (Fabricius); Selenophorus famulus Casey with Selenophorus aequinoctialis Dejean. Selenophorus schaefferi Csiki, revised status is removed from synonymy with Amblygnathus subtinctus (LeConte) and restored to species status. Discoderus discoderoides (Schaeffer), new combination is transferred from genus Selenophorus. The previous transfer from genus Selenophorus to Athrostictus punctatulus (Putzeys) is clarified. A key identifies the 15 species groups and the 37 species of adult Nearctic Selenophorus. The 24 species of Selenophorus reported for Texas make it the most species-rich state. The four kinds of sexual dimorphism in Selenophorus are found to be taxonomically useful character states. Several new state records of the United States and new country records of the New World are reported. New to the USA are one West Indian species and five Mexican species. Among the latter group is the southwestern species S. aequinoctialis, which is distinguished from the similar S. palliatus of the eastern USA. Eight strictly Neotropical species are compared to their similar Nearctic counterparts. Figures include habitus photographs of 40 species and line drawings of male genitalia for the new species.

A new species of Byrrhinus Motschulsky, 1858 (Coleoptera: Limnichidae) from Côte d'Ivoire is described: Byrrhinus confoveorum Matsumoto, new species. Photographs illustrating relevant morphological characters to distinguish this species are provided.

Platynus (Dyscolus) racquelae Liebherr and Ivie, new species is described from the Crater Rim, in the Parish of St. John Capisterre, St. Kitts, and Platynus (Dyscolus) duportei Liebherr and Ivie, new species is described from Nevis Peak, Nevis. These species are placed in the Platynus (Dyscolus) memnonius (Dejean) group, with their addition to the group extending the group's aggregate distribution northward from Basse-Terre, Guadeloupe to St. Kitts. Based on extensive collections of the Coleoptera of St. Kitts, P. racquelae appears to be restricted to only the wettest areas at highest elevations, suggesting that this species requires rather specific conditions present only in the most extreme montane sites. The beetles also exhibit moderate flight wing reduction involving diminution of wing veins associated with wing-folding—specifically, veins associated with the wedge and oblongum cells—and foreshortening of the alar surface due to loss of membrane along the wing's apical margin. This suggests that individuals of P. racquelae are at best weak fliers, and that this species is not able to colonize isolated patches of suitable habitat by flight. Platynus duportei is likewise known from only the highest and wettest point on Nevis Peak, but this species exhibits fully developed flight wings. Additional records of Platynus (Dyscolus) luciae Liebherr from St Lucia, and of Glyptolenus chalybaeus (Dejean) are reported, allowing elucidation of flight wing configuration and male and female genitalia for the former, and new island records of Nevis and Saba for the latter.

A two-year field study on selected traits of the biology of the scarabaeine dung roller Sisyphus schaefferi (Linnaeus) was conducted in a natural park in the western Po Valley in northwestern Italy. Despite laboratory studies carried out over the past few decades, several aspects of the epigean behavior of the species in the wild remain uncertain. Our study revealed that 1) the species is active from early spring to late summer, with reproductive pairs being observed from mid-spring to midsummer; 2) sexual dimorphism in body weight and length is absent; 3) mating individuals are significantly heavier and longer than non-mating individuals; 4) metatibial length increases isometrically with body length and weight; 5) size and weight of the brood balls are isometric with respect to the length and weight of the male of the reproductive pair; 6) brood balls are significantly larger and heavier than food balls, and, whereas brood ball size and weight decrease as air temperature increases, food ball size and weight increase as air humidity rises, but only in non-reproductive periods; 7) pushing and pulling roles are not sex-dependent and can be reversed during the rolling process; 8) combat for balls can involve up to six individuals simultaneously.

The dytiscid beetle Laccophilus yoshitomiiWatanabe and Kamite, 2018 (Dytiscidae), distributed in Japan, is a small aquatic beetle that was first described in 2018. In the present study a L. yoshitomii population, collected from the type locality (Ishikawa Prefecture, Japan), was reared in the laboratory. The insects laid eggs individually into the main stems of Pogostemon sp. (Lamiaceae). The developmental period for the first, second, and third instar larvae was 2–6 (mean ± SD = 3.5 ± 0.8 days, n = 51), 3–8 (4.2 ± 0.9 days, n = 48), and 5–10 days (6.8 ± 1.3 days, n = 38), respectively; the landing to emergence and landing to escaping the pupal chamber stages lasted 8 (n = 1) and 9–14 days (11.3 ± 1.5 days, n = 13), respectively. A basic rearing model for this species is proposed.

Four new species of MacrelmisMotschulsky, 1860 are described from the southwestern United States and northern Mexico: Macrelmis harleyi Barr, new species from Arizona, Macrelmis mexicana Barr, new species from Mexico, Macrelmis shepardi Barr, new species from Arizona, New Mexico, Texas, and Mexico, and Macrelmis texangusta Barr, new species from Texas and Mexico. Photographic images illustrate the external morphology and male genitalia of the new species, as well as that of Macrelmis shoemakei (Brown, 1971), Macrelmis moesta (Horn, 1870), and Macrelmis texana (Schaeffer, 1911), which occur in the same geographic region. The genitalia of M. moesta and M. texana are described and illustrated for the first time. A key to the 14 known species of Macrelmis occurring in the southwestern United States and Mexico is provided, accompanied by line illustrations of the genitalia of the remaining seven Mexican species not included in the species treatments. Also included are geographic distribution maps for the seven species that are discussed in this article.

Species introductions occur around the world both inadvertently and deliberately (typically for conservation, agriculture or fisheries). However, not all introduced species become established. Understanding the factors that affect the establishment success of introduced species will help us improve species introductions for biocontrol and conservation purposes. Here we argue that important generalist arthropod predators, the Coccinellini ladybirds (Coleoptera: Coccinellidae), are an ideal taxon for investigating the establishment process of introduced species. Coccinellini are introduced accidently via plant exports, as well as deliberately as biocontrol agents to reduce agricultural pests, and a few have become invasive species. Here, using work from invasive biology and biocontrol systems, we categorize the factors affecting the successful establishment of introduced species. These factors are 1) invasiveness of the species, 2) invasibility of the recipient ecosystem and 3) stochastic events that occur after the introduction. We review how factors such as diet and competition, dispersal ability, propagule population, disturbances and climate change can be studied within these three categories to better predict the establishment success of introduced ladybirds. Our review highlights that our current understanding of the differences between successful and unsuccessful species establishments is limited. To address this, we need direct comparisons of dispersal ability and both interspecific and intraspecific variation in ladybirds. We conclude that studies of ladybirds will help to develop theories that better characterize and predict establishment success and invasive potential.

A three-year trapping study was carried out in a touchdown area following an EF1 tornado in a red spruce forest in Baxter State Park, Maine, USA during 2014–2016. Coleopteran bycatch from this study was retained and subsequently identified. This paper reports 54 new state records for Maine from this bycatch dataset. Two of these species, Hadreule elongatula (Gyllenhal) (Ciidae) and Xestobium gaspensis R. E. White (Ptinidae), are also new country records for the United States of America. Families include Anamorphidae, Anthribidae, Brentidae, Buprestidae, Cerambycidae, Ciidae, Cleridae, Cryptophagidae, Curculionidae, Dermestidae, Elateridae, Endomychidae, Eucinetidae, Latridiidae, Nitidulidae, Ptinidae, Scarabaeidae, Scraptiidae, Staphylinidae, Stenotrachelidae, Tenebrionidae, Tetratomidae, Throscidae, and Zopheridae.

The future impact of the invasive emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), on native North American buprestids is still unknown. To determine how the range and composition of native buprestid species will change over time, knowledge of historical buprestid species distributions is necessary. We utilized a biosurveillance sampling method, namely the use of the native ground-nesting hunting wasp, Cerceris fumipennis Say (Hymenoptera: Crabronidae), along with University of Minnesota Insect Collection (UMSP) records, to create a treatment for the Buprestidae of Minnesota, USA. Additional literature records are included, along with information on host plants, collection method, and collection date range for each species. We examined 5,127 specimens with Minnesota localities, documenting 108 species. Of these, 37 new state records are noted, including 11 collected from C. fumipennis nesting sites between 2013 and 2018. The strengths and limitations of sampling buprestid populations with C. fumipennis biosurveillance are discussed.

An annotated catalog of the type specimens of the subfamily Cassidinae Gyllenhal, 1813 sensu stricto (Coleoptera: Chrysomelidae) housed at the Zoological Museum of Hamburg (ZMH), Center of Natural History, Hamburg (CeNak) is provided. Information on 29 syntypes, previously unknown for the ZHM collection, is given, and new distributional records are reported for 38 Neotropical Cassidinae species, including nine new country records and 29 new province/state records.

Four newly discovered Cretaceous genera and species are established in the family Histeridae. Phasmister cristatus Caterino, new genus, new species and Carinumerus maddisoni Caterino, new genus, new species are described in the Onthophilinae. Yethiha peregrina Caterino, new genus, new species and Druantia aeterna Caterino, new genus, new species are described in the Dendrophilinae. Additionally, Onthophilus yingae Jiang et al. is reassigned to Carinumerus. The new onthophiline genera share characters with the previously described Cretaceous histerid Cretonthophilus Caterino et al. and lack characters typical of extant Onthophilinae, and the three together may represent an early diverging lineage of this subfamily. The species of Druantia shares some features with extant Dendrophilinae, and some with Yethiha, so their systematic placement is less clear. A brief diagnostic catalog of all known Cretaceous Histeridae is provided.

An updated checklist and analysis of biological and biogeographic patterns are presented for mesic montane forest in the region of Xalapa, Veracruz, Mexico originally summarized by Noguera and Atkinson (1990). Additional species encountered during recent field work as well as taxonomic and nomenclatorial changes are incorporated. The fauna is dominated by host-generalist ambrosia beetles, especially from the tribe Corthylini. The overall fauna is dominated by species and genera of Neotropical affinity, particularly those found in cooler, intermediate elevations. Species with lowland tropical distributions have larger ranges than those with montane distributions.

A new species, Lanelater andamanensis (Coleoptera: Elateridae), is described from Little Andaman Island, India. Lanelater Arnett is recorded from the Andaman and Nicobar Islands for the first time. This species is similar to the Indonesian species Lanelater sobrinus (Candèze, 1887), but differs in pubescence, elytral length ratio, grooves and punctures on the prosternum, shape of the mesal posterior margin of the metacoxa and elytral apex.

The Onthophagus brevifrons species complex (Coleoptera: Scarabaeidae: Scarabaeinae: Onthophagini) consists of the five species: Onthophagus cavernicollis Howden and Cartwright, Onthophagus subtropicus Howden and Cartwright, Onthophagus brevifrons Horn, Onthophagus cuevensis Howden and Onthophagus moroni Zunino and Halffter, all of which are strictly associated with underground habitats (caves or burrows) and are consequently considered troglobites. Nevertheless, the biology of Onthophagus Latreille species reported from caves is lacking. In this study, four grottoes in the Cuetzalan region were explored: Trompa de Elefante, El Fósil and El Nido del Murciélago (which belong to the poorly explored Gruta de Atepolihui), and the Tasalolpan cave, in the search for dung beetles. Onthophagus moroni was collected inside El Nido del Murciélago and Tasalolpan cave, representing a new record for El Nido del Murciélago, since its presence was previously recorded inside the Tasalolpan cave in 1988. Adults of O. moroni were collected alive 70 m inside the Tasalolpan cave, under a latrine of Peters' climbing rat, Tylomys nudicaudus (Peters) (Rodentia: Cricetidae). We redescribe the species, discuss its biogeography and provide an updated dichotomous key to enable the identification of the constituent species in the O. brevifrons species complex.

Two new species of Phalangogonia Burmeister, 1844 (Coleoptera: Scarabaeidae: Rutelinae: Anoplognathini: Phalangogoniina) are described: Phalangogonia azaharensis Smith, new species from Costa Rica and Phalangogonia monzoni Smith, new species from Guatemala. A revised key to species for Phalangogonia is presented, and some notable distributional records are listed.

Cylloepus dimorphus Shepard, Sites, and Rodrigues, new species (Elmidae) is described from Brazil with a sexually dimorphic abdominal ventrite 5. Males have a protruding lobe on each side of the apex of ventrite 5. Females lack the lobes and are not distinguishable from congeners.