MicroCT data provide evidence correcting the previous misidentification of an Eocene amber beetle (Coleoptera, Cicindelidae) as an extant species.

The fossil record suggests some insect species have a marked longevity. The oldest fossils purported to represent extant insect species are from the Oligocene and Eocene. One of the most cited fossils is the extant tiger beetle Tetracha carolina (Coleoptera: Cicindelidae) that was identified over a century ago by Walther Horn in Eocene Baltic amber. We examined this and compared it to the previously described cincindelid Baltic amber fossil Palaeoiresina cassolai using X-ray microscopy and 3D imaging techniques. We conclude that Horn's fossil tiger beetle specimen is conspecific with the Eocene P. cassolai and is a member of an extinct stem group lineage of Cicindelidae. Based on a review of all the tiger beetle fossils described from Cretaceous and Paleogene deposits, we found that the assignment of these fossil species to extant lineages is not supported. There are currently no synapomorphies known from fossils that can provide evidence for Cretaceous Manticorni or Megacephalini nor is there evidence for Eocene Iresina. We provide evidence that rejects the idea of a recent beetle species persisting since the Eocene period, which is crucial for using the currently known fossil Cicindelidae species to calibrate divergence dating of beetle phylogenies.

Re-collected after 55 years: a new species of Bembidion (Coleoptera, Carabidae) from California.

A new species of the carabid beetle genus Bembidion Latreille is described from the Central Valley, Los Angeles Basin, and surrounding areas of California. Bembidionbrownorumsp. nov. is a distinctive species, a relatively large member of the subgenus Notaphus Dejean, and within Notaphus a member of the B.obtusangulum LeConte species group. It has faint spots on the elytra and a large, convex, rounded prothorax. Of the 22 specimens from 11 localities, all but one were collected more than 55 years ago. Although the collection of the holotype in 2021 at UV light suggest the species is still extant, the lack of other recent specimens suggests the species may have a more restricted distribution than in the past, and its populations may be in decline.

Mating marks on museum specimens reveal breeding patterns in species of Pterostichus Bonelli (Carabidae, Pterostichini).

We found distinct and consistently placed, species- and sex-specific abrasions of the cuticle on museum specimens of 14 species of the Pterostichus Bonelli, 1810 (Carabidae, Pterostichini) subgenusHypherpes Chaudoir, 1838. We deduced that these marks are generated during mating and, therefore, can be used to distinguish between preserved specimens of beetles that had previously mated at the time of capture and those that had not mated. In addition to describing and detailing the occurrence of the marks and providing evidence that they are the result of mating, we demonstrate their utility for inferring life history using a museum voucher collection. By scoring these indications of mating from pinned specimens, we describe life cycle patterns in two similar, relatively closely related and sympatric species of the subgenus Hypherpes, P.vicinus Mannerheim, 1843 and P.californicus (Dejean, 1828). Both were sampled during a pitfall trap study in Contra Costa, California, USA from 2014-2019 and deposited in the Essig Museum of Entomology, UC Berkeley. Both species had very low adult activity through the drought and end of drought period prior to the spring of 2017 and are significantly more abundant in the post-drought period. Based on mating marks, both species responded to accumulated precipitation ending the drought by the emergence of an active, mostly unmated cohort of adults. The spring activity peak, following the end of the drought, was dominated by unmarked and presumably unmated beetles, but samples from subsequent springs included a nearly equal mix of beetles showing mating marks and apparently unmated beetles. The beetle activity appears to correspond more with the accumulated rainfall of the preceding rainy season than with the rains of the sample year. Beetles sampled in autumn and winter (rainy season) predominantly show mating marks. The occurrence throughout the year of beetles that are marked as having mated is consistent with iteroparous beetles with a lifespan of more than one year and also consistent with dynamic phenotypic polyvariance in which the adult activity period is synchronised by adjusting development time. The dominant pattern fits with a life cycle that is typically annual univoltine, or possibly biennial semivoltine in dry years, rainy season breeding (autumn-winter) iteroparous, with adult summer aestivation and possibly facultative larval hibernation. However, unmarked and so apparently unmated individuals and teneral adults were captured during peak activity periods regardless of the season, suggesting that either the beetles diapause as teneral adults that then complete development and become active at various points during the year and/or there are multiple periods of breeding and oviposition each year in at least some portion of the population.

Phylogenetic systematics of the genera of Thryptocerina Jeannel, 1949 and new species from New Caledonia (Coleoptera, Carabidae, Oodini).

The Oodini precinctive to New Caledonia are reviewed with nine species recognized, of which seven are newly described in two genera. Five species are described in the genus Coptocarpus Chaudoir: C. microps sp. nov., C. erwini sp. nov., C. amieuensis sp. nov., C. magnus sp. nov., and C. lescheni sp. nov. In the genus Adelopomorpha Heller two species, A. tethys sp. nov. and A. tuberculata sp. nov., are described. In order to place cladistically the newly described species in a genus, a phylogenetic analysis of a matrix of 36 characters of adult morphology was conducted including exemplar species of three putative outgroup genera, six putative ingroup thryptocerine oodine genera, and all oodine species from New Caledonia. Results show support for Thryptocerina and monophyly of Adelopomorpha. Hoplolenus LaFerté-Sénectère is not monophyletic and Hoplolenus cyllodinus Fauvel is newly combined as Coptocarpus cyllodinus comb. nov. New Caledonian species of Coptocarpus form a clade, but the Australian species of the genus included in the analysis are rendered paraphyletic by African and Malagasy genera. Implications of this preliminary study for the classification of Oodini and trends in the evolution of the female reproductive tract are discussed. A key to the New Caledonian species of Oodini is provided.

Persistence of the ground beetle (Coleoptera: Carabidae) microbiome to diet manipulation.

Host-associated microbiomes can play important roles in the ecology and evolution of their insect hosts, but bacterial diversity in many insect groups remains poorly understood. Here we examine the relationship between host environment, host traits, and microbial diversity in three species in the ground beetle family (Coleoptera: Carabidae), a group of roughly 40,000 species that synthesize a wide diversity of defensive compounds. This study used 16S amplicon sequencing to profile three species that are phylogenetically distantly related, trophically distinct, and whose defensive chemical secretions differ: Anisodactylus similis LeConte, 1851, Pterostichus serripes (LeConte, 1875), and Brachinus elongatulus Chaudoir, 1876. Wild-caught beetles were compared to individuals maintained in the lab for two weeks on carnivorous, herbivorous, or starvation diets (n = 3 beetles for each species-diet combination). Metagenomic samples from two highly active tissue types-guts, and pygidial gland secretory cells (which produce defensive compounds)-were processed and sequenced separately from those of the remaining body. Bacterial composition and diversity of these ground beetles were largely resilient to controlled changes to host diet. Different tissues within the same beetle harbor unique microbial communities, and secretory cells in particular were remarkably similar across species. We also found that these three carabid species have patterns of microbial diversity similar to those previously found in carabid beetles. These results provide a baseline for future studies of the role of microbes in the diversification of carabids.

Biosynthetic origin of benzoquinones in the explosive discharge of the bombardier beetle Brachinus elongatulus.

Bombardier beetles are well-known for their remarkable defensive mechanism. Their defensive apparatus consists of two compartments known as the reservoir and the reaction chamber. When challenged, muscles surrounding the reservoir contract sending chemical precursors into the reaction chamber where they mix with enzymes resulting in an explosive discharge of a hot noxious chemical spray containing two major quinones: 1,4-benzoquinone and 2-methyl-1,4-benzoquinone (toluquinone). Previously, it has been speculated that the biosynthesis of all benzoquinones originates from one core precursor, 1,4-hydroquinone. Careful ligation of the base of the reservoir chamber enabled us to prevent the explosive reaction and sample untransformed reservoir fluid, which showed that it accumulates significant quantities of 1,4-hydroquinone and 2-methyl-1,4-hydroquinone. We investigated the biosynthetic mechanisms leading to quinone formation by injecting or feeding Brachinus elongatulus beetles with stable-isotope-labeled precursors. Chemical analysis of defensive secretion samples obtained from 1,4-hydroquinone-d6-administered beetles demonstrated that it underwent conversion specifically to 1,4-benzoquinone. Analogously, results from m-cresol-d8 injected or fed beetles confirmed that m-cresol is metabolized to 2-methyl-1,4-hydroquinone, which is then oxidized to 2-methyl-1,4-benzoquinone in the hot spray. Our results refute the previous claim that 1,4-hydroquinone is the precursor of all substituted benzoquinones in bombardier beetles and reveal that they are biosynthetic products of two independent pathways. Most likely, the aforementioned biosynthetic channel of hydroxylation of appropriate phenolic precursors and subsequent oxidation is not restricted to bombardier beetles; it could well be a general pathway that leads to the formation of all congeners of benzoquinones, one of the most widely distributed groups of defensive compounds in arthropods. Graphical abstract.

A new subgenus for "Acalathus" advena (LeConte, 1846) and the challenge of defining Calathina based on morphological characters (Coleoptera, Carabidae, Sphodrini).

The taxonomic position of Pristodactyla advena LeConte, 1848 (= "Acalathus" advena in the sense of previous authors) is discussed in light of a novel review of the morphological characters of Calathina and closely related taxa. All Acalathus Semenov, 1889 species and all other Dolichina share the distinct character state of having the sensory pits of the apical gonocoxites reduced or absent, while these pits are well-developed in P. advena. Therefore, P. advena is moved into the genus Calathus Bonelli, 1810 (Calathina), where it is placed in the molecular phylogeny of Ruiz et al. (2010). This move necessitates the description of Certocalathus subgen. n. for this species. Diagnostic characters of the new subgenus with respect to other Calathina and Dolichina beetles are presented. Given the lack of any clear synapomorphies, the subtribe Calathina is not obviously defined by morphology alone. However, recent molecular phylogenies indicate its monophyly is highly likely and therefore diagnostic morphological characters are polythetic. The states of selected morphological characters in Calathina and Dolichina taxa are provided as a summary for this and future studies.

HCN emission by a Polydesmid Millipede Detected Remotely by Reactive Adsorption on Gold Nanoparticles Followed by Laser Desorption/Ionization Mass Spectrometry (LDI-MS).

Hydrocyanic acid (HCN) is a well-known defensive allomone in the chemical arsenal of millipedes in the order Polydesmida. The presence of HCN in the headspace vapor of adult Xystocheir dissecta (Wood, 1867), a common millipede from the San Francisco Bay Area, was traced by laser desorption/ionization-mass spectrometry (LDI-MS). To accomplish this, the headspace vapor surrounding caged, live millipedes was allowed to diffuse passively over gold-nanoparticle (AuNP) deposits placed at various distances from the emitting source. The stainless steel plates with AuNP deposits were removed and irradiated by a 355-nm laser. The gaseous ions generated in this way were detected by time-of-flight mass spectrometry. The intensity of the mass spectrometric peak detected at m/z 249 for the Au(CN)2- complex anion was compared to that of the residual Au- signal (m/z 197). Using this procedure, HCN vapors produced by the live millipedes could be detected up to 50 cm away from the source. Furthermore, the addition of H2O2, as an internal oxygen source for the gold cyanidation reaction that takes place in the AuNP deposits, significantly increased the detection sensitivity. Using the modified H2O2 addition procedure, HCN could now be detected at 80 cm from the source. Moreover, we found a decreasing intensity ratio of the Au(CN)2-/Au- signals as the distance from the emitting source increased, following an exponential-decay distribution as predicted by Fick's law of diffusion. Graphical abstract.

Review and new species of Tiferonia Darlington, 1962 (Carabidae, Abacetini).

Darlington described Tiferonia based on T. parva from New Guinea. In this review, Tiferonia leytensis sp. nov. is described from Leyte Island, Philippines, Tiferonia schoutedeni (Straneo, 1943) comb. nov. is transferred from Melanchrous Andrewes, and inclusion of Tiferonia brunnea (Jedlicka, 1935) in the genus is confirmed. Characteristics of Tiferonia and genera that have been proposed as closely related to Tiferonia are discussed and a unique character, the post-ocular sulcus, shared among species of Tiferonia and Holconotus is proposed as a synapomorphy for these two genera. A key to identify adults of the four species of Tiferonia is provided.

Local and Landscape Drivers of Carabid Activity, Species Richness, and Traits in Urban Gardens in Coastal California.

Urban ecosystems, as mosaics of residential, industrial, commercial, and agricultural land, present challenges for species survival due to impervious surface, degradation, fragmentation, and modification of natural habitat, pollution, and introduced species. Some urban habitats, such as community gardens, support biodiversity and promote ecosystem services. In gardens, local factors (e.g., vegetation, groundcover) and landscape surroundings (e.g., agriculture, built or impervious cover) may influence species abundance, richness, and functional traits that are present. We examined which local and landscape factors within 19 community gardens in the California central coast influence ground beetle (Carabidae) activity density, species richness, functional group richness, and functional traits-body size, wing morphology, and dispersal ability. Gardens with higher crop richness and that are surrounded by agricultural land had greater carabid activity density, while species and functional group richness did not respond to any local or landscape factor. Gardens with more leaf litter had lower carabid activity, and gardens with more leaf litter tended to have more larger carabids. Changes in local (floral abundance, ground cover) and landscape (urban land cover) factors also influenced the distribution of individuals with certain wing morphology and body size traits. Thus, both local and landscape factors influence the taxonomic and functional traits of carabid communities, with potential implications for pest control services that are provided by carabids.

Bembidion ambiguum (Coleoptera: Carabidae) is established in California.

BACKGROUND: The ground beetle Bembidion (Neja) ambiguum Dejean is native to Europe and north Africa, in the Mediterranean region. NEW INFORMATION: We report it from North America for the first time, from five localities around San Francisco Bay, California. The earliest record is from 2012.

Additions to the knowledge of Nevada carabid beetles (Coleoptera: Carabidae) and a preliminary list of carabids from the Great Basin National Park.

BACKGROUND: Additions to the list of Carabidae known for Nevada, USA and carabid beetles found in the Great Basin National Park, NV are reported with notes on ecology and identification resources. NEW INFORMATION: For 79 species of carabids, we present 57 new state records, two state records previously reported in online resources, one confirmation of a previous questionable record for the state, and report 22 records for the Great Basin National Park that includes three new state records.

Up high and down low: Molecular systematics and insight into the diversification of the ground beetle genus Rhadine LeConte.

Rhadine LeConte is a Nearctic genus of flightless ground beetles that is poorly studied despite its relevance to evolutionary studies of subterranean fauna. Adults are notable for their slender and leggy habitus and the wide variety of habitat preferences among species, with several known only from mountaintops while others are restricted to caves or more general subterranean habitats. In central Texas, USA there are several cave endemics relevant to conservation. Here we present the first phylogenetic hypothesis for the overall structure of the genus with an emphasis on the troglobites in central Texas. We infer the phylogeny of Rhadine from ∼2.4-kb of aligned nucleotide sites from the nuclear genes, 28S rDNA and CAD, and the mitochondrial gene COI. These data were obtained for 30 species of Rhadine as well as from members of their putative sister group, Tanystoma Motschulsky. Results reveal that Rhadine is polyphyletic, and morphological characters that have been traditionally used to classify the genus into species groups are shown to be convergent in many cases. Rhadine aside from two species of uncertain placement is composed of two major clades, Clades I and II that both include epigean and subterranean species in very unequal proportions. Clade I is primarily composed of subterranean species, and Clade II includes many epigean species and high altitude montane endemics. A clade of troglobitic, cave-restricted species in Texas includes several species of large-eyed cave Rhadine. The slender habitus typical of some species [e.g., R. exilis (Barr and Lawrence), R. subterranea (Van Dyke), R. austinica Barr] evolved independently at least three times. Major biogeographic and evolutionary patterns based on these results include: troglobitic species north of the Colorado River in Texas (that also lack lateral pronotal setae) are found to comprise a monophyletic group, beetles in caves south of the Colorado River likely form another monophyletic group, and the "species pairs" of troglobitic Rhadine known to occur in the same caves are not resolved as each other's sister group, suggesting that these caves were colonized independently by more than one lineage of Rhadine. Our divergence time estimates support a Miocene age for the split between Clade I and II Rhadine and indicate that all subterranean Clade I Rhadine began diversifying in the late Miocene-early Pliocene, contemporary with cave formation in the Balcones Escarpment.

A taxonomic review, new species and a key to species of Platycoelus Blanchard, 1843 (Coleoptera: Carabidae: Pterostichini).

Based on the study of type material for species of Platycoelus Blanchard, 1843 significant changes to the current taxonomy of species included in this genus is required. Psegmatopterus politissimus (White 1846) from New Zealand is found to be congeneric with Platycoelus species and so is a new combination. Platycoelus irideomicans (Tschitschérine 1890) status novum; P. caledonicus (Tschitschérine 1901) status novum; P. sulcatulus (MacLeay 1888) status novum; and P. planipennis (MacLeay 1871) status novum; each previously considered synonyms of P. poeciloides are each recognized as a distinct species. Five new species are described, four from Queensland, Australia: P. chongheeae sp. nov., type locality Iron Range National Park; P. orion sp. nov., type locality Normanton; P. brigalowphilus sp. nov., type locality Southwood National Park; and P. politus sp. nov., type locality Cooloola National Park. The fifth species described is P. hermes sp. nov., type locality Aitape, Papua New Guinea. These changes and additions bring the total number of species in the genus to 19. A key and habitus images for all species is provided as are illustrations of the male genitalia for species where male specimens were available.

Resolution of taxonomic problems in Australian Harpalini, Abacetini, Pterostichini, and Oodini (Coleoptera, Carabidae).

Taxonomic changes are made for several problematic Australian Carabidae in the tribes Harpalini, Abacetini, Pterostichini, and Oodini. Examination of types resulted in the synonymy of Veradia Castelnau, 1867 with Leconomerus Chaudoir, 1850; Nelidus Chaudoir, 1878, Feronista Moore, 1965, and Australomasoreus Baehr, 2007 with Cerabilia Castelnau, 1867; and newly combining Fouquetius variabilis Straneo, 1960 in the genus Pediomorphus Chaudoir, 1878; Australomasoreus monteithi Baehr, 2007 in the genus Cerabilia Castelnau, 1867; and Anatrichis lilliputana W.J. Macleay, 1888 in the genus Nanodiodes Bousquet, 1996. Cuneipectus Sloane, 1907 is placed in Pterostichini Bonelli, 1810, which is a senior synonym of Cuneipectini Sloane, 1907.

Taxonomic review of Cratocerus Dejean, 1829 (Coleoptera, Carabidae) with the description of six new species.

A diagnosis of the South and Central American genus Cratocerus Dejean (Coleoptera: Carabidae) and a key to all species is provided. Eight species are recognized including six species that are newly described: Cratocerus sinesetosus sp. n. from French Guiana and Peru; Cratocerus multisetosus sp. n. from Costa Rica and Panama; Cratocerus tanyae sp. n. from Costa Rica, Guatemala, and Mexico; Cratocerus indupalmensis sp. n. a species widely distributed throughout Central and South America; Cratocerus kavanaughi sp. n. from French Guiana and Peru; and Cratocerus culpepperi sp. n. from Peru. A lectotype for Cratocerus sulcatus Chaudoir is designated. Habitus images are provided along with illustrations and images of male genitalia, female genitalia, and diagnostic morphological characters.

A new species of Lesticus Dejean, 1828 (Coleoptera, Carabidae) from the Finisterre Range, Papua New Guinea and a key to the genera of pterostichine-like Harpalinae of New Guinea.

Lesticus finisterrae (Carabidae: Pterostichini) sp. n. (type locality: Finisterre Range, Papua New Guinea), is described and characters to differentiate it from other "Trigonotomi" species are given. A key to the genera of pterostichine-like Harpalinae of the island, including all genera of Morionini, Cratocerini, Drimostomatini, Abacetini, Loxandrini and Pterostichini, is provided. The genus Rhytisternus (Pterostichini) is for the first time reported from New Guinea, represented by the likely adventive species Rhytisternus laevis (Macleay). The previously unknown male of Stegazopteryx ivimkaensis Will (Drimostomatini) is described.

Taxonomic review of the Pterostichini and Loxandrini fauna of New Caledonia (Coleoptera, Carabidae).

The generic-level taxa included in Pterostichini and Loxandrini from New Caledonia are reviewed and a key to genera and species provided. Two new genera are described, Paniestichus and Abacophrastus, with the following new species: Paniestichus subsolianus, Abacophrastus millei, Abacophrastus chapes, Abacophrastus carnifex, Abacophrastus hobbit, Abacophrastus megalops, Abacophrastus reflexus and Abacophrastus bellorum. Abacoleptus curtus new species, is described. Notonomus irideus and Notonomus savesi are moved to Prosopogmus. Four new species of Prosopogmus are described: Prosopogmus koghisensis, Prosopogmus lescheni, Prosopogmus fortis and Prosopogmus aoupiniensis. Homalosoma griseolum is moved to Sphodrosomus. Cerabilia is newly recorded from New Caledonia and the genus is moved from Platynini to Loxandrini and therefore is the first report of Loxandrini from New Caledonia. An apparent adventive from Australia, Darodilia, is newly reported from New Caledonia.

Quantification and evidence for mechanically metered release of pygidial secretions in formic acid-producing carabid beetles.

This study is the first to measure the quantity of pygidial gland secretions released defensively by carabid beetles (Coleoptera: Carabidae) and to accurately measure the relative quantity of formic acid contained in their pygidial gland reservoirs and spray emissions. Individuals of three typical formic acid producing species were induced to repeatedly spray, ultimately exhausting their chemical compound reserves. Beetles were subjected to faux attacks using forceps and weighed before and after each ejection of chemicals. Platynus brunneomarginatus (Mannerheim) (Platynini), P. ovipennis (Mannerheim) (Platynini) and Calathus ruficollis Dejean (Sphodrini), sprayed average quantities with standard error of 0.313 +/- 0.172 mg, 0.337 +/- 0.230 mg, and 0.197 +/- 0.117 mg per spray event, respectively. The quantity an individual beetle released when induced to spray tended to decrease with each subsequent spray event. The quantity emitted in a single spray was correlated to the quantity held in the reservoirs at the time of spraying for beetles whose reserves are greater than the average amount emitted in a spray event. For beetles with a quantity less than the average amount sprayed in reserve there was no significant correlation. For beetles comparable in terms of size, physiological condition and gland reservoir fullness, the shape of the gland reservoirs and musculature determined that a similar effort at each spray event would mechanically meter out the release so that a greater amount was emitted when more was available in the reservoir. The average percentage of formic acid was established for these species as 34.2%, 73.5% and 34.1% for for P. brunneomarginatus, P. ovipennis and C. ruficollis, respectively. The average quantities of formic acid released by individuals of these species was less than two-thirds the amount shown to be lethal to ants in previously published experiments. However, the total quantity from multiple spray events from a single individual could aggregate to quantities at or above the lethal level, and lesser quantities are known to act as ant alarm pheromones. Using a model, one directed spray of the formic acid and hydrocarbon mix could spread to an area of 5-8 cm diameter and persisted for 9-22 seconds at a threshold level known to induce alarm behaviors in ants. These results show that carabid defensive secretions may act as a potent and relatively prolonged defense against ants or similar predators even at a sub-lethal dose.