Dispersal of thermophilic beetles across the intercontinental Arctic forest belt during the early Eocene

Estimating the Age of Poorly Dated Fossil Specimens and Deposits Using a Total-Evidence Approach and the Fossilized Birth-Death Process

Bayesian total-evidence approaches under the fossilized birth-death model enable biologists to combine fossil and extant data while accounting for uncertainty in the ages of fossil specimens, in an integrative phylogenetic analysis. Fossil age uncertainty is a key feature of the fossil record as many empirical data sets may contain a mix of precisely dated and poorly dated fossil specimens or deposits. In this study, we explore whether reliable age estimates for fossil specimens can be obtained from Bayesian total-evidence phylogenetic analyses under the fossilized birth-death model. Through simulations based on the example of the Baltic amber deposit, we show that estimates of fossil ages obtained through such an analysis are accurate, particularly when the proportion of poorly dated specimens remains low and the majority of fossil specimens have precise dates. We confirm our results using an empirical data set of living and fossil penguins by artificially increasing the age uncertainty around some fossil specimens and showing that the resulting age estimates overlap with the recorded age ranges. Our results are applicable to many empirical data sets where classical methods of establishing fossil ages have failed, such as the Baltic amber and the Gobi Desert deposits. [Bayesian phylogenetic inference; fossil age estimates; fossilized birth-death; Lagerstätte; total-evidence.].

Formation of the Holarctic Fauna: Dated molecular phylogenetic and biogeographic insights from the Quedius-lineage of Ground-Dwelling Rove Beetles (Coleoptera, Staphylinidae)

Although the Holarctic fauna has been explored for centuries, many questions on its formation are still unanswered. For example, i) what was the impact of the uplift of the Himalaya and Tibetan Plateau?, ii) what were the timings and climate of the faunal bridges connecting the Nearctic and Palearctic regions?, and iii) how did insect lineages respond to the late Paleogene global cooling and regional aridification? To answer these, we developed a phylogenetic dataset of 1229 nuclear loci for a total of 222 species of rove beetles (Staphylinidae) with emphasis in the tribe Quediini, especially Quedius-lineage and its subclade Quedius sensu stricto. Using eight fossils for calibrating molecular clock, we estimated divergence times and then analysed in BioGeoBEARS paleodistributions of the most recent common ancestor for each target lineage. For each species we generated climatic envelopes of the temperature and precipitation and mapped them across the phylogeny to explore evolutionary shifts. Our results suggest that the warm and humid Himalaya and Tibetan Plateau acted as an evolutionary cradle for the Quedius-lineage originating during the Oligocene from where, in the Early Miocene, the ancestor of the Quedius s. str. dispersed into the West Palearctic. With the climate cooling from the Mid Miocene onwards, new lineages within Quedius s. str. emerged and gradually expanded distributions across the Palearctic. In Late Miocene, a member of the group dispersed to the Nearctic region via Beringia before the closure of this land bridge 5.3 Ma. Paleogene global cooling and regional aridification largely shaped the current biogeographic pattern for Quedius s. str. species, many of them originating during the Pliocene and shifting or contracting their ranges during Pleistocene.

New Burmese Amber Rove Beetle Fossils Assigned to the Rare Extant Subfamily Coomaniinae (Coleoptera: Staphylinidae)

The Mesozoic, ca. 99-million-year-old Burmese amber is an incredible source of fossil beetles that have been very actively studied in recent times and have already significantly improved our knowledge about the evolution of the large family of Staphylinidae, the rove beetles. Nevertheless, new extinct taxa of high phylogenetic interest are being discovered, among which the following three rove beetle species are described here: Coomania megistos sp. nov., Coomania enkarsios sp. nov. and Coomania yini sp. nov. These fossils preserved enough morphological characters to be identified as members of the rove beetle lineage formed by Staphylininae and allied subfamilies. Based on the fragments of morphology available for observation, they are hypothesized to be the extinct members of the extant rare monobasic subfamily Coomaniinae, sister to the recently mega-diverse and abundant Staphylininae. Limitations of the available fossil material prompted us to place the new species in the extant, monobasic genus Coomania Cameron, 1939, pending a more refined generic placement when more characters become available via additional material or advanced examination techniques. The odd morphology and rarity of the extant members of Coomaniinae restricted to Southeast Asia and Northern Australia make them an enigmatic subfamily among the hyper-diverse Staphylinidae. The newly described fossils, albeit without sufficient details concealed by imperfect preservation, shed some light on the past diversity of Coomaniinae and its divergence from Staphylininae.

From monocots to dicots: host shifts in Afrotropical derelomine weevils shed light on the evolution of non-obligatory brood pollination mutualism

Weevils from the tribe Derelomini (Curculionidae: Curculioninae) are specialized brood pollinators engaged in mutualistic relationships with several angiosperm lineages. In brood pollination systems, reproductive plant tissues are used for the development of insect larval stages, whereas adult insects pollinate their plant hosts as a reward. The evolutionary history of derelomines in relationship to their hosts is poorly understood and potentially contrasts with other brood pollination systems, wherein a pollinator lineage is usually associated with a single host plant family. In the case of Afrotropical Derelomini, host records indicate a diverse host repertoire consisting of several families of monocot and dicot plants. In this study, we investigate their phylogenetic relationships, timing of diversification and evolution of host use. Our results suggest that derelomine lineages started their diversification ~40 Mya. Reconstructions of host use evolution support an ancestral association with the monocotyledonous palm family (Arecaceae), followed by several shifts towards other plant families in Afrotropical lineages, especially to dicotyledonous plants from the family Ebenaceae (on the genus Euclea L.). Some level of phylogenetic conservatism of host use is recovered for the lineages associated with either palms or Euclea. Multiple instances of sympatric weevil assemblages on the same plant are also unravelled, corresponding to either single or independent colonization events. Overall, the diversity of hosts colonized and the frequency of sympatric assemblages highlighted in non-obligatory plant–derelomine brood pollination systems contrast with what is generally expected from plant–insect brood pollination systems.

Revision of rove beetle genus Bolitogyrus Chevrolat (Staphylininae, Cyrtoquediini). Supplement 1

Bolitogyrus is a moderately diverse genus of 78 species that are widely disjunct in the subtropical and tropical forests of the Neotropical and Oriental regions. Following recent revisions of both the Neotropical and Oriental species, this study provides new distributional data, a revised species concept for Bolitogyrusstrigifrons (Wendeler) sensu nov., and the description of B.pseudostrigifronssp. nov. and B.nigropolitoidessp. nov., bringing the total number of Bolitogyrus species to 80. Several keys are updated to reflect the newly available data and new species.

Phylogeny indicates polyphyly in Cnodocentron (Trichoptera: Xiphocentronidae): biogeography and revision of New World species (Caenocentron)

Cnodocentron has a disjunct Laurasian distribution, with species in South-East Asia and the New World. It is divided into two subgenera: Cnodocentron and Caenocentron. Here, we infer the evolutionary history of the genus through phylogenetic and biogeographic data combining COI and 46 morphological characters. Phylogenetic relationships and divergence-time estimation were simultaneously inferred through Bayesian inference. The dating analysis was performed through relaxed morphological and molecular clocks. The historical biogeography was investigated using the dispersal–extinction–cladogenesis model. Our results indicate the polyphyly of the genus Cnodocentron, with each subgenus being more related to other genera than to each other. Therefore, the subgenus Caenocentron is elevated to genus status here. The biogeographical analysis showed that the Oriental Cnodocentron diverged in the Indian subcontinent during the Middle Eocene, while the New World Caenocentron stat. nov. originated in the Chortis Block in the Late Eocene. The dispersal of Caenocentron to South America occurred only after the Late Miocene, around 10 Mya. Additionally, we provide a revision of Caenocentron, with an identification key and description of the male and female of two new species from Costa Rica: Caenocentron carlosdelarosai sp. nov. and Caenocentron rafamoralesi sp. nov..

Njoerdichthys dyckerhoffi gen. et sp. nov. (Pycnodontiformes, lower Turonian) northward migration caused by the Cretaceous Thermal Maximum

A new pycnodont taxon, Njoerdichthys dyckerhoffi gen. et sp. nov., from the Turonian of the Lower Saxony Basin of Germany is described and its systematic positions is established based on phylogenetic analyses of three specimens using slightly altered data matrices. All analyses display some differences to previous analyses but show very similar results to each other apart from the interpretation of the position of several taxa such as, e.g., Palaeobalistum. The new pycnodontiform specimens from northwestern Germany are unambiguously identified as a derived member of Pycnodontidae with close relationships to Abdobalistum and Nursallia? goedeli because of the unique combination of characters. One of the three specimens represents a juvenile form. Its morphological characters are limited, but it shares some characters with Njoerdichthys dyckerhoffi gen. et sp. nov. and is consequently allocated to the new taxon. The systematic placement of the new taxon, Njoerdichthys gen. nov., within Pycnodontidae is surprising since it does not display the one autapomorphic character (postparietal brush-like extension for muscle attachment) previously proposed to define this clade, but rather displays a combination of derived and homoplastic characters indicating that the definition of supra-generic taxa needs to be re-evaluated in the future by including more and new taxa. The distribution of pycnodontiform fishes in the Cretaceous appears to concur with changes in global climatic conditions, where high upper-ocean temperatures and high sea levels allow these fishes to migrate into higher latitudes as evidenced by the occurrence of the new taxon and Anomoeodus subclavatus in the Campanian of Sweden.

New Data, Old Story: Molecular Data Illuminate the Tribal Relationships among Rove Beetles of the Subfamily Staphylininae (Coleoptera: Staphylinidae)

The megadiverse subfamily Staphylininae traditionally belonged to the best-defined rove beetle taxa, but the advent of molecular phylogenetics in the last decade has brought turbulent changes to the group's classification. Here, we reevaluate the internal relationships among the tribes of Staphylininae by implementing tree inference methods that suppress common sources of systematic error. In congruence with morphological data, and in contrast to some previous phylogenetic studies, we unambiguously recover Staphylininae and Paederinae as monophyletic in the traditional sense. We show that the recently proposed subfamily Platyprosopinae (Arrowinus and Platyprosopus) is a phylogenetic artefact and reinstate Arrowinus as a member of Arrowinini stat. res. and Platyprosopus as a member of Platyprosopini stat. res. We show that several recent changes to the internal classification of the subfamily are phylogenetically unjustified and systematically unnecessary. We, therefore, reestablish Platyprosopini, Staphylinini, and Xantholinini as tribes within Staphylininae (all stat. res.) and recognize Coomaniini as a tribe (stat. nov.) rather than subfamily. Consequently, the traditional ranks of the subtribes Acylophorina, Afroquediina, Amblyopinina, Antimerina, †Baltognathina, Cyrtoquediina, Erichsoniina, Hyptiomina, Indoquediina, Quediina, and Tanygnathinina are restored (all stat. res.). We review the current classification of Staphylininae and discuss sources of incongruence in multigene phylogenies.

Mesozoic sooty mould beetles as living relicts in New Zealand

New Zealand is an island continent that completed its split from the Gondwanan continent at 52 Ma, harbouring an iconic biota of tuatara, kiwi and weta. The sooty mould community is a distinctive trophic element of New Zealand forest ecosystems that is driven by plant-feeding sternorrhynchan Hemiptera. These produce honeydew, which supports fungal growth, which in turn supports numerous endemic invertebrates, including endemic New Zealand beetle families. Ancient New Zealand insect fossils are rare but a single fossil of a sooty mould cyclaxyrid was recently described from Cretaceous Burmese amber, a family that was previously known from two extant New Zealand species. Well-preserved fossils like this one are recasting Earth history, and, based on a wealth of additional specimens, we re-evaluate the taxonomy of Cretaceous cyclaxyrids and one Eocene species here transferred to Cyclaxyridae. Cyclaxyridae are highly tied to the sooty mould community and have now been discovered to occur in disparate biogeographic realms in deep time. Our discovery indicates that the family, and perhaps the sooty mould community in general, was widespread in Pangaea from at least the Cretaceous and survived as a relict in New Zealand. Persistence of a sooty mould ecosystem in New Zealand and fungal specialization may not necessarily be an evolutionary 'dead-end' for cyclaxyrids and other insects.

Congruence of morphological and molecular phylogenies of the rove beetle subfamily Staphylininae (Coleoptera: Staphylinidae)

Staphylininae is the third largest subfamily of the enormous family Staphylinidae. Monophyly of Staphylininae and its sister relationship to the subfamily Paederinae have been broadly accepted according to both conventional morphology- and molecular-based phylogenies until the last three years. Recent molecular phylogenies rejected monophyly of Staphylininae and regarded Paederinae as a clade within it. This paper re-evaluates the recent molecular work, aiming to clarify the relationship between Staphylininae and Paederinae and resolve intertribal relationships within Staphylininae. Based on a new six-gene data set (5707 bp) for 92 taxa including Oxyporinae (outgroup), representatives of Paederinae, and members of all extant tribes of Staphylininae from published DNA data in GenBank, we generated a well-resolved phylogeny of Staphylininae with all deep nodes (intertribal relationships) strongly supported, and reassert the hypothesis that Staphylininae is monophyletic and indeed the sister group to Paederinae using both Bayesian and maximum likelihood inference. Additionally, our study is a case-study to show that both outgroup selection and completeness of nucleotide data can influence the outcome of a molecular phylogeny. With an increasing number of staphylinid fossils being discovered, the robust phylogeny of Staphylininae inferred by our research will provide a good framework for understanding the early evolution of this group.

Origins of Afrotropical freshwater fishes

The Afrotropics house a diverse freshwater ichthyofauna with > 3000 species, almost all of which are endemic. Recent progress in dated phylogenetics and palaeontology of several groups of Afrotropical freshwater fishes (AFFs) has allowed the testing of palaeoecology- and palaeogeography-based hypotheses explaining their early presence in Africa. Seven hypotheses were tested for 37 most-inclusive monophyletic groups of AFFs. Results indicated that ten lineages originated from direct, but asynchronous, marine-to-freshwater shifts. These lineages contribute < 2% to the current AFF species richness. Eleven lineages colonized the Afrotropics from the Orient after the Afro-Arabian plate collided with Eurasia in the early Oligocene. These lineages contribute ~20% to the total diversity. There are seven sister relationships between Afrotropical and Neotropical taxa. For only three of them (4% of the species diversity), the continental drift vicariance hypothesis was not rejected. Distributions of the other four younger trans-Atlantic lineages are better explained by post-drifting long-distance dispersal. In those cases, I discuss the possibility of dispersal through the Northern Hemisphere as an alternative to direct trans-Atlantic dispersal. The origins of ten AFF lineages, including the most species-rich Pseudocrenilabrinae (> 1100 species), are not yet established with confidence.

Unexpected palaeodiversity of omaliine rove beetles in Eocene Baltic amber (Coleoptera, Staphylinidae, Omaliinae)

Fossil records of the subfamily Omaliinae are fragmentary and most of them are less informative compression fossils. Baltic amber from the mid-Eocene of northern Europe is one of the most important sources of insect fossils, but only two reliably placed omaliines have been described. Here, we provide a general overview of this subfamily in Baltic amber. In total, five new extinct species of four genera in three tribes are described and illustrated: Geodromicusbalticussp. nov. (Anthophagini), Eusphalerumkantisp. nov. (Eusphalerini), Paraphloeostibamorosasp. nov., Phyllodrepadaedalisp. nov., and Ph.icarisp. nov. (Omaliini). Additionally, we report on four species belonging to Eusphalerum, which remain unnamed, from the same amber deposit. The records of Eusphalerum include the first fossils of the tribe Eusphalerini, while that of Geodromicus may represent the second and the first definitive fossil record of the genus and tribe Anthophagini. Our discoveries highlight the unexpected palaeodiversity of Omaliinae in Baltic amber, further reinforcing the coexistence of thermophilous and temperate-loving beetles in Baltic amber and potentially indicating wetland and riparian habitats of amber-producing forests.

Baltic amber Staphylinini (Coleoptera: Staphylinidae: Staphylininae): a rove beetle fauna on the eve of our modern climate

Cenozoic climate cooling, particularly during the Eocene, has drastically shaped modern biological assemblages through a shift from an equable greenhouse to a polarized icehouse. Present-day Europe lies in a highly seasonal and temperate area that strongly embodies this modern icehouse climate. Baltic amber provides a Middle Eocene snapshot of the European fauna before this large-scale change. Here, we focused on the rove beetle tribe Staphylinini and conducted a comprehensive phylogenetic study of all known Baltic amber fossils in a total-evidence phylogenetic framework that integrates morphology with molecular data from six gene fragments. Based on our well-resolved topology, we propose the following: †Baltognathina subtrib. nov., Afroquediina subtrib. nov., Antimerina subtrib. nov., †Baltognathus aenigmaticus gen. et sp. nov., †Eolophorus gen. nov., †Laevisaurus robustus and †Laevisaurus gracilis gen. et spp. nov., †Hemiquedius europaeus sp. nov. and †Bolitogyrus fragmentus sp. nov. †Quedius cretaceus is placed as junior synonym of †Cretoquedius infractus. The earliest definitive fossils of Quediina are reported herein from the Eocene. The Staphylinini fauna of Middle Eocene Europe combined thermophilic, freeze-intolerant lineages with freeze-tolerant, temperate lineages and, unlike most other staphylinid or beetle lineages, all have since become extinct in the Palaearctic region.

Fossil evidence of elytra reduction in ship-timber beetles

Beetles (Coleoptera) comprise about one quarter of all described animal species. One of the main contributors to their evolutionary success is the elytra, or hardened forewings, which have protective functions while maintaining their ability to fly. Unlike other beetles, some ship-timber beetles (Lymexylidae) have extremely small elytra and largely exposed functional hindwings. There is little fossil evidence illuminating the evolutionary history of short elytra in lymexylids. Here, I report five well-preserved lymexylid fossils in mid-Cretaceous and Cenozoic ambers from Myanmar (ca. 99 million years ago [Mya]), Russia (ca. 44 Mya), and the Dominican Republic (ca. 16 Mya). Three Cretaceous fossils have strongly reduced, shortened elytra, with unexpected variation in elytral size and shape, whereas very small, modified elytra are found only in much younger Dominican amber. These morphologically diverse extinct lymexylids shed new light on the early origin and evolutionary history of elytra reduction and its diverse variation in the ship-timber beetles. Based on the striking morphological similarities with extant lymexylids, these extinct taxa might have had the same, or similar, ecological, behavioural, and flight modes as the extant ship-timber beetles.