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.

SignificanceWe have developed an ultraflexible organic photovoltaic (OPV) that achieves sufficient thermal stability of up to 120 °C and a high power conversion efficiency of 10% with a total thickness of 3 μm. By combining an inherently stable donor:acceptor blend as the active layer and ultrathin substrate and barriers with excellent thermal capability, we were able to overcome the trade-offs between efficiency, stability, and device thickness. The ultraflexible and thermally stable OPV can be easily integrated into textiles through the commercially available hot-melt process without causing performance degradation, thereby presenting great potential as a ubiquitous and wearable power source in daily life.

The evolution of eusociality in ants and termites propelled both insect groups to their modern ecological dominance. Yet, eusociality also fostered the evolution of social parasitism—an adverse symbiosis, in which the superorganismal colonies formed by these insects are infiltrated by a profusion of invertebrate species that target nest resources. Predominant among these are the aleocharine rove beetles (Staphylinidae), a vast and ecologically diverse subfamily with numerous morphologically and behaviourally specialized socially parasitic lineages. Here, we report a fossil aleocharine, Mesosymbion compactus gen. et sp. nov., in Burmese amber (∼99 million years old), displaying specialized anatomy that is a hallmark of social parasites. Mesosymbion coexisted in the Burmese palaeofauna with stem-group ants and termites that provide the earliest indications of eusociality in both insect groups. We infer that the advent of eusociality led automatically and unavoidably to selection for social parasitism. The antiquity and adaptive flexibility of aleocharines made them among the first organisms to engage in this type of symbiosis.

Triassic fossils are rare but crucial for understanding the early evolution of large insect clades including beetles (Coleoptera). Their phylogenetic assignment is problematic because of fragmentary preservation, yet crucial for the correct use of the information they provide. Here an analysis is presented of the phylogenetic position of Leehermania prorova, the Late Triassic compressed fossil which was described and hitherto widely used as the oldest representative of Staphylinidae (rove beetles) in the suborder Polyphaga. By contrast with the intuitive character assessment made in the original description, a phylogenetic analysis of Leehermania is performed using an extensive morphological matrix of extant Coleoptera provided by the Beetle Tree of Life project, constrained in view of the latest relevant molecular phylogenies. As a result, Leehermania is identified as an extinct lineage within the beetle suborder Myxophaga, closest to the modern family Hydroscaphidae. Excluding Leehermania from Staphylinidae and placing it in Myxophaga amends erroneous assumptions about early diversification of rove beetles and enhances our views of the evolutionary history of Coleoptera.