Cretophengodidae, a new Cretaceous beetle family, sheds light on the evolution of bioluminescence.

Bioluminescent beetles of the superfamily Elateroidea (fireflies, fire beetles, glow-worms) are the most speciose group of terrestrial light-producing animals. The evolution of bioluminescence in elateroids is associated with unusual morphological modifications, such as soft-bodiedness and neoteny, but the fragmentary nature of the fossil record discloses little about the origin of these adaptations. We report the discovery of a new bioluminescent elateroid beetle family from the mid-Cretaceous of northern Myanmar (ca 99 Ma), Cretophengodidae fam. nov. Cretophengodes azari gen. et sp. nov. belongs to the bioluminescent lampyroid clade, and would appear to represent a transitional fossil linking the soft-bodied Phengodidae + Rhagophthalmidae clade and hard-bodied elateroids. The fossil male possesses a light organ on the abdomen which presumably served a defensive function, documenting a Cretaceous radiation of bioluminescent beetles coinciding with the diversification of major insectivore groups such as frogs and stem-group birds. The discovery adds a key branch to the elateroid tree of life and sheds light on the evolution of soft-bodiedness and the historical biogeography of elateroid beetles.

The comprehensive phylogeny of the superfamily Elateroidea (Coleoptera: Elateriformia).

Elateriformia consists of Dascilloidea, Buprestoidea (jewel beetles), Byrrhoidea and Elateroidea (click beetles, fireflies and relatives). Numerous elateroid lineages contain taxa with modified metamorphosis resulting in sexual maturity while retaining larval characters. Additionally, they evolved unique defensive strategies including clicking mechanism, aposematic coloration and bioluminescence. To investigate the phylogenetic position of Elateroidea within Coleoptera, we merged 1048 newly produced 18S rRNA, 28S rRNA, rrnL mtDNA, and cox1 mtDNA sequences for ∼300 elateriform taxa with data from GenBank. The 975-taxa dataset aligned in BlastAlign was analyzed under maximum likelihood criterion. The results agreed in most aspects with the current morphology-based classification and results of molecular studies. Elateriformia were monophyletic and Elateroidea were sister to Byrrhoidea. Further, we analyzed all-data (513 elateriform taxa) and pruned matrix (417 elateriform taxa, all fragments present) using parsimony and maximum likelihood methods to reveal the phylogenetic relationships among elateroid lineages and examine the evolution of soft-bodiedness, neoteny and bioluminescence. We confirmed the monophyly of Elateroidea sensu lato and most of the families, with Telegeusidae inferred in most trees within paraphyletic Omethidae. The clade Artematopodidae+Telegeusidae+Omethidae was a sister to remaining elateroids. All topologies reject the relationships of hard-bodied Elateridae, Eucnemidae, Throscidae and Cerophytidae, formerly supposed to be a monophylum. Eucnemidae and Throscidae formed independent lineages and the position of Cerophytidae was variable - either a sister to Throscidae, or an independent lineage. The Lampyridae+Cantharidae clade was in most trees sister to Phengodidae+Rhagophthalmidae+Omalisidae+Elateridae. Molecular phylogeny of Elateroidea confirmed the multiple origins of soft-bodied, neotenic and light emiting lineages. On the basis of our molecular phylogeny, we place former Telegeusidae as a subfamily in Omethidae.

A review of Drilini (Coleoptera: Elateridae: Agrypninae) of the Northern Levant, with description of a new species from Syria and a key to Levantine species.

The species of the elaterid soft-bodied tribe Drilini from the Levant are reviewed. All known species are redescribed and Drilus nemethi sp. nov. is described. Drilus adustus (Chevrolat, 1854), comb. nov. and D. akbesianus (Fairmaire, 1895), comb. nov. are transferred from Malacogaster Bassi, 1834 to Drilus Olivier, 1790. Drilus posticus Schaufuss, 1867, syn. nov. is a junior subjective synonym of Drilus adustus (Chevrolat, 1854). All Levantine species are keyed and diagnostic characters are illustrated. Their distribution, morphological diversity and the statuses of type specimens of Drilus reitteri Bourgeois, 1908 and Cydistus reitteri Bourgeois, 1885 are discussed.

A new species of Rhagophthalmus Motschulsky, 1854 (Coleoptera, Rhagophthalmidae) from Laos represents the smallest known member of the genus.

Rhagophthalmus Motschulsky, 1854 is the most speciose genus in Rhagophthalmidae, distributed in the region encompassing South, East, and Southeast Asia. Here, we describe R.nanussp. nov. from the Houaphanh Province of eastern Laos, which represents the smallest known species in Rhagophthalmus and one of the smallest in Rhagophthalmidae. We compare it with the morphologically similar and geographically close congeners and provide a preliminary identification key to adult males of Rhagophthalmus species from mainland Southeast Asia. Additionally, we discuss the morphology and variability of male genitalia within Rhagophthalmus.

A new species of Eurypogon Motschulsky (Coleoptera: Artematopodidae) from China, with notes on E. sanzang Wang & Liu.

Eurypogon Motschulsky, 1859 is a small artematopodid genus from the Nearctic and Palaearctic realms, with only three species known from mainland China. Here, we describe Eurypogon schuhi Packova & Kundrata, sp. nov. from the Hubei province in China, which is similar in the black body coloration to the recently described Eurypogon sanzang Wang & Liu, 2021 from the Henan province. Both species differ mainly in the ratio of basal antennomeres, elytral surface and proportions, and shape of male genitalia. We report populations of E. sanzang from the Qinling Shan in the Shaanxi province (a new province record) and from the Xiong'er Shan in the Henan province. Additionally, we describe the female of E. sanzang and discuss intraspecific variability in male genitalia. We provide images of main diagnostic characters for both species.

An updated catalogue of Agrypninae (Coleoptera: Elateridae) from Pakistan.

The updated catalogue of Agrypninae from Pakistan is provided. We list 86 described species classified in 18 genera and five tribes (Agrypnini, Drilini, Hemirhipini, Oophorini, and Pseudomelanactini). More than one third of species are currently endemic to Pakistan. For each species we provide information on distribution and relevant bibliography. The following new combinations are proposed for species hitherto included in Conoderus Eschscholtz, 1829 (since Conoderus is currently a synonym of Monocrepidius Eschscholtz, 1829): Monocrepidius aeolodermoides (Platia, 2015) comb. nov., Monocrepidius cylindricus (Platia & Ahmed, 2016) comb. nov., Monocrepidius drasterioides (Platia & Ahmed, 2016) comb. nov., Monocrepidius nigromaculosus (Vats & Chauhan, 1992) comb. nov., Monocrepidius mithiensis (Platia & Ahmed, 2016) comb. nov., and Monocrepidius vartiani (Platia, 2015) comb. nov. Additionally, Conoderus pakistanicus Mangi, Pahnwar & Shaikh, 2022 is synonymized with Lanelater bipunctatus (Candèze, 1857).

Plastocerus angulosus (Germar, 1844) (Coleoptera: Elateridae: Dendrometrinae): an enigmatic click beetle with a convoluted taxonomic history.

Plastocerus angulosus (Germar, 1844) is one of the only two species of genus Plastocerus Schaum, 1852 within the monogeneric click beetle tribe Plastocerini. It is distributed in the area comprising Greece, Turkey, Syria, Israel, and Lebanon (first record for Lebanon published here). Due to the slightly modified morphology of P. angulosus, this taxon has a convoluted taxonomic history and was earlier classified in various families and even superfamilies. However, recent phylogenies place it in Elateridae: Dendrometrinae. In this study, we review the morphology, intraspecific morphological and genetic variability, sexual dimorphism, systematics, bibliography, and distribution of P. angulosus. Our results show rather low morphological and relatively high genetic variability in this species. Females, which are larger than males and differ mainly in the antennae and abdominal ventrites, are not so rare as previously thought. Further field research should focus on the discovery of immature stages to describe their morphology and understand their biology and ecology.

Descriptions of two new flightless species of Pseudocsikia Schimmel & Platia (Coleoptera, Elateridae, Dimini) from Taiwan Island, China, with a definition of the formosana species-group.

Two new flightless click beetle species, Pseudocsikiachoui sp. nov. and Pseudocsikiachanjuan sp. nov., are described and illustrated from Taiwan, China. Their habitus and diagnostic characters are illustrated. The two species most resemble P.formosana, which is endemic to Taiwan, by the strongly protruding pronotal anterior angles accompanied by pits and the shape of aedeagus. They can be all grouped as the P.formosana-species group. A key to the species of the P.formosana-species group and an updated checklist of Chinese Pseudocsikia with supplementary notes on type localities are provided. The discovery of two new species highlights the potential species-richness of the flightless click-beetles on Taiwan Island.

Diversity of the Paedomorphic Snail-Eating Click-Beetle Genus Malacogaster Bassi, 1834 (Elateridae: Agrypninae: Drilini) in the Mediterranean.

The soft-bodied click-beetle genus Malacogaster Bassi, 1834 from the Mediterranean region has never been taxonomically revised to date. Information on its morphology, intra- and interspecific variability, systematics and distribution is fragmented and most species have not been properly studied since their description. Therefore, in this study we summarize all available information on the genus Malacogaster. Altogether, we recognize 10 valid species from the area including the Canary Islands, Iberian Peninsula, Balearic Islands, northern coast of Africa, Sardinia, and Sicily. Malacogaster ruficollis Dodero, 1925, stat. nov., which was originally described as a variety of M. bassii Lucas, 1870 and later synonymized with it, is considered a separate species. Malacogaster parallelocollis Reitter, 1894, syn. nov. and M. olcesei var. reductus Pic, 1951, syn. nov. are synonymized with M. maculiventris Reitter, 1894. Malacogaster notativentris Pic, 1951, syn. nov. and M. olcesei Pic, 1951, syn. nov. are synonymized with M. passerinii Bassi, 1834. Lectotypes are designated for M. maculiventris Reitter, 1894, M. nigripes heydeni Reitter, 1894, M. parallelocollis Reitter, 1894, M. thoracica Redtenbacher, 1858, M. olcesei Pic, 1951, and M. rubripes Peyerimhoff, 1949 to fix their identity.

First Artematopodidae from mid-Cretaceous amber of northern Myanmar (Coleoptera: Elateroidea).

Artematopodid fossils from the mid-Cretaceous Burmese amber are reported for the first time, represented by three species in two genera. Bipogonia Li, Kundrata Cai gen. nov. with two species, B. trivialis Li, Kundrata Cai sp. nov. and B. fortis Li, Kundrata Cai sp. nov., is mainly characterized by the distinctly serrate antennae, mandibles with both apical and subapical teeth, and prosternum without paired longitudinal ridges. Carinibipogonia xiai Li, Kundrata Cai gen. et sp. nov. shares with Bipogonia the distinctly serrate antennae and mandibles with both apical and subapical teeth but differs mainly in the prosternum with short paired longitudinal ridges. Based on their morphology, the two new genera might be related to the extant Allopogonia; however, this needs to be tested in the future with a phylogenetic framework.

Dominican amber net-winged beetles suggest stable paleoenvironment as a driver for conserved morphology in a paedomorphic lineage.

Paedomorphosis is a heterochronic syndrome in which adult individuals display features of their immature forms. In beetles, this phenomenon occurs widely in the superfamily Elateroidea, including the net-winged beetles (Lycidae), and, due to the usual flightlessness of paedomorphic females, it is hypothesized to cause speciation rates higher than in non-paedomorphic lineages. However, some fossils of paedomorphic lycids do not support this with palaeobiological data. Discovery of new Lycidae fossils attributed to the West Indian extant paedomorphic genus Cessator Kazantsev in the Dominican amber also suggests morphological stasis within this genus in the Greater Antilles. We describe Cessator anachronicus Ferreira and Ivie, sp. nov. based on adult males, as well as the first ever recorded fossil net-winged beetle larva of the same genus. We propose that the relatively young age of the studied fossils combined with the stable conditions in the forest floor of the Greater Antilles through the last tens of million years could explain the exceptionally conserved morphology in the net-winged beetles affected by the paedomorphic syndrome.

Rhagophthalmidae Olivier, 1907 (Coleoptera, Elateroidea): described genera and species, current problems, and prospects for the bioluminescent and paedomorphic beetle lineage.

Rhagophthalmidae are a small beetle family known from the eastern Palaearctic and Oriental realms. Rhagophthalmidae are closely related to railroad worms (Phengodidae) and fireflies (Lampyridae) with which they share highly modified paedomorphic females and the ability to emit light. Currently, Rhagophthalmidae include 66 species classified in the following 12 genera: Bicladodrilus Pic, 1921 (two spp.), Bicladum Pic, 1921 (two spp.), Dioptoma Pascoe, 1860 (two spp.), Diplocladon Gorham, 1883 (two spp.), Dodecatoma Westwood, 1849 (eight spp.), Falsophrixothrix Pic, 1937 (six spp.), Haplocladon Gorham, 1883 (two spp.), Menghuoius Kawashima, 2000 (three spp.), Mimoochotyra Pic, 1937 (one sp.), Monodrilus Pic, 1921 (two spp. in two subgenera), Pseudothilmanus Pic, 1918 (two spp.), and Rhagophthalmus Motschulsky, 1854 (34 spp.). The replacement name Haplocladongorhami Kundrata, nom. nov. is proposed for Diplocladonhasseltii Gorham, 1883b (described in subgenus Haplocladon) which is preoccupied by Diplocladonhasseltii Gorham, 1883a. The genus Reductodrilus Pic, 1943 is tentatively placed in Lampyridae: Ototretinae. Lectotypes are designated for Pseudothilmanusalatus Pic, 1918 and P.marginalis Pic, 1918. Interestingly, in the eastern part of their distribution, Rhagophthalmidae have remained within the boundaries of the Sunda Shelf and the Philippines demarcated by the Wallace Line, which separates the Oriental and Australasian realms. This study is intended to be a first step towards a comprehensive revision of the group on both genus and species levels. Additionally, critical problems and prospects for rhagophthalmid research are briefly discussed.

Nothotytthonyx, a new genus of Malthininae (Coleoptera, Cantharidae) from mid-Cretaceous amber of northern Myanmar.

A new fossil genus and species of Cantharidae, Nothotytthonyxserratus Li, Biffi, Kundrata & Cai gen. et sp. nov., is reported from mid-Cretaceous Burmese amber. The new species is tentatively attributed to the extant subfamily Malthininae based on a combination of characters, including the symmetrical apical maxillary palpomeres, shortened elytra, pronotum with arched margins and well-defined borders, tibiae with apical spurs, and tarsal claws simple, although its well-developed gonostyli are atypical in Malthininae. The discovery of Nothotytthonyx also suggests a possible Gondwanan origin for Malthininae.

A New Species of Vetubrachypsectra from Mid-Cretaceous Amber of Northern Myanmar (Coleoptera: Brachypsectridae).

A new species, Vetubrachypsectra huchengi Li, Kundrata & Cai sp. nov., is described from mid-Cretaceous Burmese amber on the basis of a single adult female. The species is assigned to genus Vetubrachypsectra Qu & Cai based on its serrate antennae, long maxillary palps, presence of tibial spurs, and elytra without clear striae. Vetubrachypsectra huchengi differs distinctly from V. burmitica Qu & Cai, the only other species in the genus, in having the pedicel apically attached to the scape. Some other differences between the female of V. huchengi and the male of V. burmitica include less serrate antennae, a broader pronotal disc, a broader scutellar shield and smaller tibial spurs. However, at least some of these characters can be considered sexually dimorphic.

Functional Morphology of the Thorax of the Click Beetle Campsosternus auratus (Coleoptera, Elateridae), with an Emphasis on Its Jumping Mechanism.

We investigated and described the thoracic structures, jumping mechanism, and promesothoracic interlocking mechanism of the click beetle Campsosternus auratus (Drury) (Elateridae: Dendrometrinae). Two experiments were conducted to reveal the critical muscles and sclerites involved in the jumping mechanism. They showed that M2 and M4 are essential clicking-related muscles. The prosternal process, the prosternal rest of the mesoventrite, the mesoventral cavity, the base of the elytra, and the posterodorsal evagination of the pronotum are critical clicking-related sclerites. The destruction of any of these muscles and sclerites resulted in the loss of normal clicking and jumping ability. The mesonotum was identified as a highly specialized saddle-shaped biological spring that can store elastic energy and release it abruptly. During the jumping process of C. auratus, M2 contracts to establish and latch the clicking system, and M4 contracts to generate energy. The specialized thoracic biological springs (e.g., the prosternum and mesonotum) and elastic cuticles store and abruptly release the colossal energy, which explosively raises the beetle body in a few milliseconds. The specialized trigger muscle for the release of the clicking was not found; our study supports the theory that the triggering of the clicking is due to the building-up of tension (i.e., elastic energy) in the system.

The first mainland European Mesozoic click-beetle (Coleoptera: Elateridae) revealed by X-ray micro-computed tomography scanning of an Upper Cretaceous amber from Hungary.

Fossil bioinclusions in amber are invaluable source of information on the past evolution and diversity of various organisms, as well as on the paleoecosystems in general. The click-beetles, Elateridae, which originated and greatly diversified during the Mesozoic, are mostly known from the adpression-like fossils, and their diversity in the Cretaceous ambers is only poorly documented. In this study, we describe a new click-beetle based on an incomplete inclusion in ajkaite, an Upper Cretaceous (Santonian) amber from the Ajka Coal Formation from Hungary. We used X-ray micro-computed tomography scanning to reconstruct its morphology because it is deposited in an opaque piece of amber. Our results suggest that the newly described Ajkaelater merkli gen. et sp. nov. belongs to subfamily Elaterinae. It represents the first Mesozoic beetle reported from Hungary, and the first Mesozoic Elateridae formally described from mainland Europe. Our discovery supports an Eurasian distribution and diversification of Elaterinae already in the Cretaceous. The paleoenvironment of the Ajka Coal Formation agrees well with the presumed habitat preference of the new fossil taxon. The discovery of a presumably saproxylic click-beetle shed further light on the yet poorly known paleoecosystem of the Santonian present-day western Hungary.

Integrated phylogenomics and fossil data illuminate the evolution of beetles.

Beetles constitute the most biodiverse animal order with over 380 000 described species and possibly several million more yet unnamed. Recent phylogenomic studies have arrived at considerably incongruent topologies and widely varying estimates of divergence dates for major beetle clades. Here, we use a dataset of 68 single-copy nuclear protein-coding (NPC) genes sampling 129 out of the 193 recognized extant families as well as the first comprehensive set of fully justified fossil calibrations to recover a refined timescale of beetle evolution. Using phylogenetic methods that counter the effects of compositional and rate heterogeneity, we recover a topology congruent with morphological studies, which we use, combined with other recent phylogenomic studies, to propose several formal changes in the classification of Coleoptera: Scirtiformia and Scirtoidea sensu nov., Clambiformia ser. nov. and Clamboidea sensu nov., Rhinorhipiformia ser. nov., Byrrhoidea sensu nov., Dryopoidea stat. res., Nosodendriformia ser. nov. and Staphyliniformia sensu nov., and Erotyloidea stat. nov., Nitiduloidea stat. nov. and Cucujoidea sensu nov., alongside changes below the superfamily level. Our divergence time analyses recovered a late Carboniferous origin of Coleoptera, a late Palaeozoic origin of all modern beetle suborders and a Triassic-Jurassic origin of most extant families, while fundamental divergences within beetle phylogeny did not coincide with the hypothesis of a Cretaceous Terrestrial Revolution.

The genus Selasia Laporte, 1838 (Coleoptera: Elateridae: Agrypninae) in Sri Lanka.

The neotenic click-beetle genus Selasia Laporte, 1838 has a centre of diversity in the tropical Africa but also includes several species known from the Palearctic and Oriental regions. In this study, we review the Selasia fauna of Sri Lanka. We describe S. ivanae sp. nov., redescribe S. apicalis Pic, 1914, and discuss the systematic placement of S. isabellae Bourgeois, 1909, which is probably a firefly and is considered incertae sedis.

Hide-and-Seek with Tiny Neotenic Beetles in One of the Hottest Biodiversity Hotspots: Towards an Understanding of the Real Diversity of Jurasaidae (Coleoptera: Elateroidea) in the Brazilian Atlantic Forest.

Jurasaidae are a family of neotenic elateroid beetles which was described recently from the Brazilian Atlantic Forest biodiversity hotspot based on three species in two genera. All life stages live in the soil, including the larviform females, and only adult males are able to fly. Here, we report the discovery of two new species, Jurasai miraculum sp. nov. and J. vanini sp. nov., and a new, morphologically remarkable population of J. digitusdei Rosa et al., 2020. Our discovery sheds further light on the diversity and biogeography of the group. Most species of Jurasaidae are known from the rainforest remnants of the Atlantic Forest, but here for the first time we report a jurasaid species from the relatively drier Atlantic Forest/Caatinga transitional zone. Considering our recent findings, minute body size and cryptic lifestyle of all jurasaids, together with potentially high numbers of yet undescribed species of this family from the Atlantic Forest and possibly also other surrounding ecoregions, we call for both field research in potentially suitable localities as well as for a detailed investigation of a massive amount of already collected but still unprocessed materials deposited in a number of Brazilian institutes, laboratories and collections.

Notes on the Morphology and Systematic Position of Archaeolus Lin, 1986, from the Jurassic of South China (Coleoptera: Elateroidea).

The morphology of the Jurassic fossil Archaeolus funestus Lin, 1986, which was previously placed in the extinct click-beetle subfamily Protagrypninae (Coleoptera: Elateridae), is revised based on a re-examination of the type specimen. The validity of Protagrypninae is discussed and further questioned, partly based on the newly observed characters in A. funestus, including the surface sculpture of the mesoventrite. A possible Throscidae affinity of monotypic Archaeolus Lin, 1986, as suggested in a recent study, is further critically reviewed.