New fossils of Elateridae (Insecta, Coleoptera) from Early Cretaceous Jinju Formation (South Korea) with their implications to evolutionary diversity of extinct Protagrypninae

Cretaceous beetles from Jinju Formation: Trachypachidae (Coleoptera: Adephaga)

Here we describe two new species, Psacodromeus recta sp. nov. and Necronectulus lazarus sp. nov., that belong to the family Trachypachidae. Only one species of the genus Psacodromeus, P. minor, was reported from the Gurvaneren Formation in Mongolia, which is estimated as Early Cretaceous. Other species of the genus Psacodromeus, including P. crassus, P. gutta, P. ovalis, and P. rugosus, were reported from the Karabastau Formation in Kazakhstan, which is dated to the Late Jurassic. Necronectulus avus, which is the only species of the genus Necronectulus, was reported from the Tologoi Formation in Kazakhstan, which is dated to the Late Triassic. Therefore, our study has expanded the fossil record of the genera Psacodromeus and Necronectulus from the Early Cretaceous.

Enigmatic Campyloxenus: Shedding light on the delayed origin of bioluminescence in ancient Gondwanan click beetles

Gondwanan elaterids, previously thought to be unrelated, include bioluminescent Campyloxenus earlier placed in bioluminescent Pyrophorinae. Genomic data suggest close relationships between Gondwanan groups. We maintain Morostomatinae and Hapatesinae and redefine Pityobiinae with Nearctic Pityobiini, Gondwanan Parablacini stat. nov., Campyloxenini stat. nov., and Tibionemini trib. nov. Their ancestors putatively underwent differentiation in Gondwana during the Cretaceous separation of southern continents. In contrast with their age, extant groups are species poor. Campyloxenus represents a recent origin of bioluminescence, no older than ∼53 my. Its large pronotal lanterns differ from Pyrophorini and resemble color patches of sympatric beetle co-mimics. This discovery highlights the fourth or fifth origin of bioluminescence in Elateroidea, alongside the lampyroid clade, click beetles Pyrophorini, Alampoides and Coctilelater in Anaissini (Pyrophorinae), and Balgus schnusei (Thylacosterninae). While our phylogenetic findings illuminate the phylogenetic aspects, the complete story awaits further field observations and in-depth genomic analyses of biochemical pathways used by bioluminescent elateroids.

Burmogonus gen. nov., a New Click Beetle (Coleoptera: Elateridae: Elaterinae) from Mid-Cretaceous Burmese Amber

The click beetles (Elateridae) originated in the Mesozoic and recently form a relatively large family with approximately 10,000 described species worldwide. However, the Mesozoic, and particularly Cretaceous, click beetle fauna remains very poorly known. Here we describe Burmogonus cretaceus gen. et sp. nov. based on a single, relatively well-preserved, specimen from the mid-Cretaceous Burmese amber. This species can be assigned with confidence to the subfamily Elaterinae, and based on the supra-antennal carinae being incomplete across the head and directed to the labrum, the shape of metacoxal plates, and simple tarsi, we tentatively place it in the tribe Elaterini. We discuss the morphology of a new genus and other Elaterinae described from Burmese amber.

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

Simple Summary

Elateroidea is one of the large superfamilies in the beetle suborder Polyphaga. Many adpression-type elateroid fossils were insufficiently described, which hinders the interpretation of their systematic position. Here, we figure and re-describe an elateroid fossil, Archaeolus funestus, from the Jurassic of South China. Our observations support that Archaeolus might be a member of the Throscidae family.

Abstract

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.

The Fossil Record of Elateridae (Coleoptera: Elateroidea): Described Species, Current Problems and Future Prospects

The Elateridae (click-beetles) are the largest family in Elateroidea; however, their relationships, systematics and classification remain unclear. Our understanding of the origin, evolution, palaeodiversity and palaeobiogeography of Elateridae, as well as reconstruction of a reliable time-calibrated phylogeny for the group, are hampered by the lack of detailed knowledge of their fossil record. In this study, we summarize the current knowledge on all described fossil species in Elateridae, including their type material, geographic origin, age, bibliography and remarks on their systematic placement. Altogether, 261 fossil species classified in 99 genera and nine subfamilies are currently listed in this family. The Mesozoic click-beetle diversity includes 143 species, with most of them described from the Jurassic Karatau, and 118 described species are known from the Cenozoic deposits, mainly from the Eocene North American Florissant Formation and European Baltic amber. Available data on the described past diversity of Elateridae suggest that almost all fossil lineages in this group are in urgent need of revision and numerous Mesozoic species might belong to different families. Our study is intended to serve as a comprehensive basis for all subsequent research focused on the click-beetle fossil record.

Click Beetle Mitogenomics with the Definition of a New Subfamily Hapatesinae from Australasia (Coleoptera: Elateridae)

Elateridae is a taxon with very unstable classification and a number of conflicting phylogenetic hypotheses have been based on morphology and molecular data. We assembled eight complete mitogenomes for seven elaterid subfamilies and merged these taxa with an additional 22 elaterids and an outgroup. The structure of the newly produced mitogenomes showed a very similar arrangement with regard to all earlier published mitogenomes for the Elateridae. The maximum likelihood and Bayesian analyses indicated that Hapatesus Candèze, 1863, is a sister of Parablacinae and Pityobiinae. Therefore, Hapatesinae, a new subfamily, is proposed for the Australian genera Hapatesus (21 spp.) and Toorongus Neboiss, 1957 (4 spp.). Parablacinae, Pityobiinae, and Hapatesinae have a putative Gondwanan origin as the constituent genera are known from the Australian region (9 genera) and Neotropical region (Tibionema Solier, 1851), and only Pityobius LeConte, 1853, occurs in the Nearctic region. Another putative Gondwanan lineage, the Afrotropical Morostomatinae, forms either a serial paraphylum with the clade of Parablacinae, Pityobiinae, and Hapatesinae or is rooted in a more terminal position, but always as an independent lineage. An Eudicronychinae lineage was either recovered as a sister to Melanotini or as a deep split inside Elaterinae and we herein transfer the group to Elaterinae as Eudicronychini, a new status. The mitochondrial genomes provide a sufficient signal for the placement of most lineages, but the deep bipartitions need to be compared with phylogenomic analyses.

X-ray micro-computed tomography reveals a unique morphology in a new click-beetle (Coleoptera, Elateridae) from the Eocene Baltic amber

Beetle fossils are a rich source of information about the palaeodiversity and evolutionary history of the order Coleoptera. Despite the increasing rate of fossil research on click-beetles (Coleoptera: Elateridae), the most diverse group in the superfamily Elateroidea, their fossil record has remained largely unstudied. This may be caused by the combination of their rather uniform external morphology and the suboptimal state of preservation and visibility in most fossil specimens. Here, we used X-ray micro-computed tomography to reconstruct the morphology of an interesting click-beetle from Eocene Baltic amber, which had some principal diagnostic characters obscured by opaque bubbles and body position. Our results suggest that the newly described Baltelater bipectinatus gen. et sp. nov. belongs to tribe Protelaterini within subfamily Lissominae. Since Protelaterini have a predominantly Gondwanan distribution, our discovery is of a great importance for the historical biogeography of the group. Very distinctive are the bipectinate antennae with 11 antennomeres and with rami beginning on antennomere IV, which are not found in any recent Elateridae. The discovery of a new click-beetle lineage from European Eocene amber sheds further light on the palaeodiversity and historical diversification of the family as well as on the composition of the extinct amber forest ecosystem.

Fossil Genera in Elateridae (Insecta, Coleoptera): A Triassic Origin and Jurassic Diversification

Insect fossils bear important information about the evolutionary history of the group. The fossil record of Elateridae, a large cosmopolitan beetle family, has been greatly understudied and the available data are often replete with ambiguity and uncertainty. The research of Elateridae evolution cannot be done without solid genus-group name concepts. In this study we provide an updated comprehensive summary of the fossil genera in Elateridae, including their systematic placement and information on the type species, gender, number of species, age range, and relevant bibliography. We list seven valid fossil genera in Agrypninae, one in Cardiophorinae, two in Dendrometrinae, five in Elaterinae, two in Negastriinae, one in Omalisinae, one in Pityobiinae, and 36 in Protagrypninae. Additional 19 genera are tentatively classified as Elateridae incertae sedis, and their placements are discussed. Further, we move genera Babuskaya Martins-Neto & Gallego, 2009, Cardiosyne Martins-Neto & Gallego, 2006, Fengningia Hong, 1984 and Gemelina Martins-Neto & Gallego, 2006 from Elateridae to Coleoptera incertae sedis. We also discuss the genera previously placed in Elateridae, which are currently not included in the family. The data on the fossil generic diversity suggest that Elateridae originated in the Triassic and rapidly diversified and became comparatively abundant through the Jurassic. We call for further research on the fossil Elateridae from various deposits in order to increase our knowledge on the origin, evolution, and palaeodiversity of the group.