Classification of weevils as a data-driven science: leaving opinion behind

Large carrion and burying beetles evolved from Staphylinidae (Coleoptera, Staphylinidae, Silphinae): a review of the evidence

Large carrion beetles (Silphidae) are the focus of ongoing behavioral ecology, forensic, ecological, conservation, evolutionary, systematic, and other research, and were recently reclassified as a subfamily of Staphylinidae. Twenty-three analyses in 21 publications spanning the years 1927-2023 that are relevant to the question of the evolutionary origin and taxonomic classification of Silphidae are reviewed. Most of these analyses (20) found Silphidae nested inside Staphylinidae (an average of 4.38 branches deep), two found Silphidae in an ambiguous position, and one found Silphidae outside Staphylinidae, as sister to Hydrophilidae. There is strong evidence supporting the hypothesis that large carrion beetles evolved from within Staphylinidae and good justification for their classification as the subfamily Silphinae of the megadiverse, and apparently now monophyletic, Staphylinidae. Considerable uncertainty remains regarding the interrelationships and monophyly of many staphylinid subfamilies. Nonetheless, the subfamily Tachyporinae was found to be the sister of Silphinae in more analyses (7) than any other subfamily.

Diversity of Auger Beetles (Coleoptera: Bostrichidae) in the Mid-Cretaceous Forests with Description of Seven New Species

The diversity and abundance of auger beetles were compared with ecologically similar families of other beetles. It was shown that the ecological niche in dead wood, which in the Paleogene belonged to bark and ambrosia beetles, was occupied by Bostrichidae in the Mesozoic. Seven new species, Poinarinius aristovi sp. nov., P. antonkozlovi sp. nov., P. lesnei sp. nov., P. perkovskyi sp. nov., P. zahradniki sp. nov., P. borowskii sp. nov., and P. cretaceus sp. nov. from the subfamily Alitrepaninae of the family Bostrichidae are described from mid-Cretaceous Burmese amber. The key to the species of the genus Poinarinius Legalov, 2018 is given. The new synonym, Alitrepanum Peng, Jiang, Engel & Wang, 2022, syn. nov. to Poinarinius, was established. A list of the fossil Bostrichidae was compiled.

The Namaini, a new weevil tribe with six new genera from South Africa (Coleoptera: Curculionidae: Entiminae)

Based on a phylogenetic analysis of a large number of mainly undescribed edaphic Entiminae from South Africa, a new tribe of entimine weevils is described, which includes six new genera. Taxa included in Namaini trib. nov. are clustered into seven clades that are used to delimit the following genera: Nama, type genus of the tribe, plus the new genera Cederbergia gen. nov., Cervellaea gen. nov., Namaquania gen. nov., Pentamerica gen. nov., Springbokia gen. nov. and Yamalaka gen. nov. A key to the genera is given and four new species are described.

Telomeric DNA sequences in beetle taxa vary with species richness

Telomeres are protective structures at the ends of eukaryotic chromosomes, and disruption of their nucleoprotein composition usually results in genome instability and cell death. Telomeric DNA sequences have generally been found to be exceptionally conserved in evolution, and the most common pattern of telomeric sequences across eukaryotes is (TxAyGz)n maintained by telomerase. However, telomerase-added DNA repeats in some insect taxa frequently vary, show unusual features, and can even be absent. It has been speculated about factors that might allow frequent changes in telomere composition in Insecta. Coleoptera (beetles) is the largest of all insect orders and based on previously available data, it seemed that the telomeric sequence of beetles varies to a great extent. We performed an extensive mapping of the (TTAGG)n sequence, the ancestral telomeric sequence in Insects, across the main branches of Coleoptera. Our study indicates that the (TTAGG)n sequence has been repeatedly or completely lost in more than half of the tested beetle superfamilies. Although the exact telomeric motif in most of the (TTAGG)n-negative beetles is unknown, we found that the (TTAGG)n sequence has been replaced by two alternative telomeric motifs, the (TCAGG)n and (TTAGGG)n, in at least three superfamilies of Coleoptera. The diversity of the telomeric motifs was positively related to the species richness of taxa, regardless of the age of the taxa. The presence/absence of the (TTAGG)n sequence highly varied within the Curculionoidea, Chrysomeloidea, and Staphylinoidea, which are the three most diverse superfamilies within Metazoa. Our data supports the hypothesis that telomere dysfunctions can initiate rapid genomic changes that lead to reproductive isolation and speciation.

Origin and evolution of fungus farming in wood-boring Coleoptera - a palaeontological perspective

Insect-fungus mutualism is one of the better-studied symbiotic interactions in nature. Ambrosia fungi are an ecological assemblage of unrelated fungi that are cultivated by ambrosia beetles in their galleries as obligate food for larvae. Despite recently increased research interest, it remains unclear which ecological factors facilitated the origin of fungus farming, and how it transformed into a symbiotic relationship with obligate dependency. It is clear from phylogenetic analyses that this symbiosis evolved independently many times in several beetle and fungus lineages. However, there is a mismatch between palaeontological and phylogenetic data. Herein we review, for the first time, the ambrosia system from a palaeontological perspective. Although largely ignored, families such as Lymexylidae and Bostrichidae should be included in the list of ambrosia beetles because some of their species cultivate ambrosia fungi. The estimated origin for some groups of ambrosia fungi during the Cretaceous concurs with a known high diversity of Lymexylidae and Bostrichidae at that time. Although potentially older, the greatest radiation of various ambrosia beetle lineages occurred in the weevil subfamilies Scolytinae and Platypodinae during the Eocene. In this review we explore the evolutionary relationship between ambrosia beetles, fungi and their host trees, which is likely to have persisted for longer than previously supposed.

Monogamous sperm storage and permanent worker sterility in a long-lived ambrosia beetle

The lifetime monogamy hypothesis claims that the evolution of permanently unmated worker castes always requires maximal full-sibling relatedness to be established first. The long-lived diploid ambrosia beetle Austroplatypus incompertus (Schedl) is known to be highly social, but whether it has lifetime sterile castes has remained unclear. Here we show that the gallery systems of this beetle inside the heartwood of live Eucalyptus trees are always inhabited by a single core family, consisting of a lifetime-inseminated mother, permanently unmated daughter workers, and immatures that are always full siblings to each other and their adult caretakers. Overall sex ratios are even. Males always disperse and only survive as stored sperm, but female offspring either disperse to mate and found their own colony or assume unmated worker roles, probably surviving for many years without any reproductive potential because tarsal loss precludes later dispersal. A well-supported Platypodinae phylogeny has allowed us to infer that parental monogamy evolved before a lifetime-unmated worker caste emerged, confirming the prediction that monogamy and full-sibling relatedness are necessary conditions for the evolution of such workers. The initially very challenging but ultimately long-term stable nesting habitat in live trees appears to have provided the crucial benefit/cost factor for maintaining selection for permanently sterile workers after strict monogamy and lifetime sperm storage had become established in this curculionid coleopteran lineage.

Molecular phylogeny and biogeography of the weevil subfamily Platypodinae reveals evolutionarily conserved range patterns

Platypodinae is a peculiar weevil subfamily of species that cultivate fungi in tunnels excavated in dead wood. Their geographical distribution is generally restricted, with genera confined to a single continent or large island, which provides a useful system for biogeographical research. This study establishes the first detailed molecular phylogeny of the group, with the aim of testing hypotheses on classification, diversification, and biogeography. A phylogeny was reconstructed based on 3648 nucleotides from COI, EF-1α, CAD, ArgK, and 28S. Tree topology was well resolved and indicated a strong correlation with geography, more so than predicted by previous morphology-based classifications. Tesserocerini was paraphyletic, with Notoplatypus as the sister group to a clade consisting of three main lineages of Tesserocerini and the recently evolved Platypodini. Austroplatypus formed the sister group to all remaining Platypodini and hence confirmed its separate status from Platypus. The Indo-Australian genera of Platypodini were strikingly paraphyletic, suggesting that the taxonomy of this tribe needs careful revision. Ancestral-area reconstructions in Lagrange and S-DIVA were ambiguous for nodes roughly older than 80 Ma. More recent events were firmly assessed and involved post-Gondwanan long-distance dispersal. The Neotropics was colonized three times, all from the Afrotropical region, with the latest event less than 25 Ma that included the ancestor of all Neotropical Platypodini.