Expanding the Mesozoic Record of Early Brachyceran Fly Larvae, including New Larval Forms with Chimera-Type Morphologies.

Diptera are one of the four megadiverse groups of holometabolan insects. Flies perform numerous ecological functions, especially in their larval stages. We can assume that this was already the case in the past; however, fly larvae remain rare in most deposits. Here we report new dipteran larvae preserved in Cretaceous (about 99 Ma) Kachin amber from Myanmar and, even older, Jurassic (about 165 Ma) compression fossils from China. Through light microscopy and micro-CT scanning we explore their peculiar morphology and discuss their possible phylogenetic affinities. Several larvae seem to represent the lineage of Stratiomyomorpha. A few others present characters unique to Xylophagidae (awl-flies), as well as to Athericidae (water sniper-flies), resulting in a chimeric morphology. Understanding the exact relationships of most of these specimens with a particular lineage remains challenging, since they differ considerably from any other known dipteran larvae and present some unique traits. Additionally, we report new specimens of Qiyia jurassica Chen et al., 2014, supposedly parasitic larvae, most likely representatives of Athericidae. These new findings offer valuable insights into the evolution of the early diversification of the brachyceran flies and underscore the importance of immature stages in understanding the evolutionary history and ecology of flies.

Mechanical and elemental characterization of ant mandibles: consequences for bite mechanics.

Mandible morphology has an essential role in biting performance, but the mandible cuticle can have regional differences in its mechanical properties. The effects of such a heterogeneous distribution of cuticle material properties in the mandible responses to biting loading are still poorly explored in chewing insects. Here, we tested the mechanical properties of mandibles of the ant species Formica cunicularia by nanoindentation and investigated the effects of the cuticular variation in Young's modulus (E) under bite loading with finite-element analysis (FEA). The masticatory margin of the mandible, which interacts with the food, was the hardest and stiffest region. To unravel the origins of the mechanical property gradients, we characterized the elemental composition by energy-dispersive X-ray spectroscopy. The masticatory margin possessed high proportions of Cu and Zn. When incorporated into the FEA, variation in E effectively changed mandible stress patterns, leading to a relatively higher concentration of stresses in the stiffer mandibular regions and leaving the softer mandible blade with relatively lower stress. Our results demonstrated the relevance of cuticle E heterogeneity in mandibles under bite loading, suggesting that the accumulation of transition metals such as Cu and Zn has a relevant correlation with the mechanical characteristics in F. cunicularia mandibles.

Mechanical, physical and thermal properties of composite materials produced with the basidiomycete Fomes fomentarius.

BACKGROUND: To achieve climate neutrality, fundamentally new concepts of circularity need to be implemented by the building sector as it contributes to 40% of anthropogenic CO2 emission. Fungal biotechnology can make a significant contribution here and help eliminate fossil dependency for building material production. Recently, we have shown that the medicinal polypore Fomes fomentarius feeds well on renewable lignocellulosic biomass and produces composite materials that could potentially replace fossil fuel-based expanded polystyrene as insulation material. RESULTS: In this study, we explored the mechanical, physical, and thermal properties of F. fomentarius-based composite materials in more detail and determined key performance parameters that are important to evaluate the usability of F. fomentarius-based composite materials in the construction sector. These parameters were determined according to European standards and included compressive strength, modulus of elasticity, thermal conductivity, water vapour permeability, and flammability of uncompressed composites as well as flexural strength, transverse tensile strength, and water absorption capacity of heat-pressed composites, among others. We could show that uncompressed composites obtained from F. fomentarius and hemp shives display a thermal conductivity of 0.044 W (m K)-1 which is in the range of natural organic fibres. A water vapour permeability of 1.72 and classification into flammability class B1 clearly surpasses fossil-based insulation materials including expanded polystyrene and polyurethane. We could furthermore show that heat-pressing can be used to reliably generate stiff and firm particleboards that have the potential to replace current wood-based particleboards that contain synthetic additives. X-ray microcomputed tomography finally visualized for the first time the growth of hyphae of F. fomentarius on and into the hemp shive substrates and generated high-resolution images of the microstructure of F. fomentarius-based composites. CONCLUSION: This study demonstrates that fungal-based composites produced with F. fomentarius partially meet or even exceed key performance parameters of currently used fossil fuel-based insulation materials and can also be used to replace particleboards.

A new pseudoscorpion genus (Garypinoidea: Garypinidae) from the Eocene supports extinction and range contraction in the European paleobiota.

During the Paleogene, the Holarctic experienced drastic climatic oscillations, including periods of extensive glaciation. These changes had a severe impact on both the flora and fauna causing widespread extinction and range shifts with some taxa retreating to refugia in the Mediterranean Basin. Here we provide evidence for this hypothesis using fossils from the pseudoscorpion family Garypinidae Daday, 1889 (Arachnida: Pseudoscorpiones). This family comprises 21 extant genera from all continents except Antarctica but is restricted to low mid-latitudes (<44°N) in the Northern Hemisphere. We provide the second record of garypinids from the European succinite ambers of the Eocene by describing the first extinct genus in Garypinidae, Baltamblyolpium gen. nov., which includes two species: Baltamblyolpium gizmotum sp. nov. from Baltic amber and Baltamblyolpium grabenhorsti sp. nov. from Bitterfeld amber. The new genus exhibits a morphology that closely resembles Neoamblyolpium Hoff, 1956 from western North America and the genus Amblyolpium Simon, 1898, which is widespread but includes taxa restricted to Mediterranean refugia in Europe. The discovery of a new fossil genus of Garypinidae from Europe confirms that the family was found at more northerly latitudes during the Eocene, however, extinction and range contraction resulted in their present-day relictual distribution in southern Europe like many other lineages that once thrived in the European "Baltic amber forest" of the Eocene.

Synchrotron radiation-based microcomputed tomography for three-dimensional growth analysis of Aspergillus niger pellets.

Filamentous fungi produce a wide range of relevant biotechnological compounds. The close relationship between fungal morphology and productivity has led to a variety of analytical methods to quantify their macromorphology. Nevertheless, only a µ-computed tomography (µ-CT) based method allows a detailed analysis of the 3D micromorphology of fungal pellets. However, the low sample throughput of a laboratory µ-CT limits the tracking of the micromorphological evolution of a statistically representative number of submerged cultivated fungal pellets over time. To meet this challenge, we applied synchrotron radiation-based X-ray microtomography at the Deutsches Elektronen-Synchrotron [German Electron Synchrotron Research Center], resulting in 19,940 3D analyzed individual fungal pellets that were obtained from 26 sampling points during a 48 h Aspergillus niger submerged batch cultivation. For each of the pellets, we were able to determine micromorphological properties such as number and density of spores, tips, branching points, and hyphae. The computed data allowed us to monitor the growth of submerged cultivated fungal pellets in highly resolved 3D for the first time. The generated morphological database from synchrotron measurements can be used to understand, describe, and model the growth of filamentous fungal cultivations.

On the material dependency of peri-implant morphology and stability in healing bone.

The microstructural architecture of remodeled bone in the peri-implant region of screw implants plays a vital role in the distribution of strain energy and implant stability. We present a study in which screw implants made from titanium, polyetheretherketone and biodegradable magnesium-gadolinium alloys were implanted into rat tibia and subjected to a push-out test four, eight and twelve weeks after implantation. Screws were 4 mm in length and with an M2 thread. The loading experiment was accompanied by simultaneous three-dimensional imaging using synchrotron-radiation microcomputed tomography at 5 µm resolution. Bone deformation and strains were tracked by applying optical flow-based digital volume correlation to the recorded image sequences. Implant stabilities measured for screws of biodegradable alloys were comparable to pins whereas non-degradable biomaterials experienced additional mechanical stabilization. Peri-implant bone morphology and strain transfer from the loaded implant site depended heavily on the biomaterial utilized. Titanium implants stimulated rapid callus formation displaying a consistent monomodal strain profile whereas the bone volume fraction in the vicinity of magnesium-gadolinium alloys exhibited a minimum close to the interface of the implant and less ordered strain transfer. Correlations in our data suggest that implant stability benefits from disparate bone morphological properties depending on the biomaterial utilized. This leaves the choice of biomaterial as situational depending on local tissue properties.

A multiscale approach reveals elaborate circulatory system and intermittent heartbeat in velvet worms (Onychophora).

An antagonistic hemolymph-muscular system is essential for soft-bodied invertebrates. Many ecdysozoans (molting animals) possess neither a heart nor a vascular or circulatory system, whereas most arthropods exhibit a well-developed circulatory system. How did this system evolve and how was it subsequently modified in panarthropod lineages? As the closest relatives of arthropods and tardigrades, onychophorans (velvet worms) represent a key group for addressing this question. We therefore analyzed the entire circulatory system of the peripatopsid Euperipatoides rowelli and discovered a surprisingly elaborate organization. Our findings suggest that the last common ancestor of Onychophora and Arthropoda most likely possessed an open vascular system, a posteriorly closed heart with segmental ostia, a pericardial sinus filled with nephrocytes and an impermeable pericardial septum, whereas the evolutionary origin of plical and pericardial channels is unclear. Our study further revealed an intermittent heartbeat-regular breaks of rhythmic, peristaltic contractions of the heart-in velvet worms, which might stimulate similar investigations in arthropods.

Adult and Larval Tracheal Systems Exhibit Different Molecular Architectures in Drosophila.

Knowing the molecular makeup of an organ system is required for its in-depth understanding. We analyzed the molecular repertoire of the adult tracheal system of the fruit fly Drosophila melanogaster using transcriptome studies to advance our knowledge of the adult insect tracheal system. Comparing this to the larval tracheal system revealed several major differences that likely influence organ function. During the transition from larval to adult tracheal system, a shift in the expression of genes responsible for the formation of cuticular structure occurs. This change in transcript composition manifests in the physical properties of cuticular structures of the adult trachea. Enhanced tonic activation of the immune system is observed in the adult trachea, which encompasses the increased expression of antimicrobial peptides. In addition, modulatory processes are conspicuous, in this case mainly by the increased expression of G protein-coupled receptors in the adult trachea. Finally, all components of a peripheral circadian clock are present in the adult tracheal system, which is not the case in the larval tracheal system. Comparative analysis of driver lines targeting the adult tracheal system revealed that even the canonical tracheal driver line breathless (btl)-Gal4 is not able to target all parts of the adult tracheal system. Here, we have uncovered a specific transcriptome pattern of the adult tracheal system and provide this dataset as a basis for further analyses of the adult insect tracheal system.

First record of Jacobsoniidae (Coleoptera) on the African continent in Holocene copal from Tanzania: biogeography since the Cretaceous.

Neither fossil nor living Jacobsoniidae are found in abundance. Derolathrus cavernicolus Peck, 2010 is recorded here preserved in Holocene copal from Tanzania with an age of 210 ± 30 BP years. This leads us to three interesting conclusions: (1) This is the first time the family was found on the African continent, extending the family's distribution range to hitherto unknown localities. Derolathrus cavernicolus in Holocene copal from Tanzania expands the known distribution of the species, previously only recorded in the USA (Hawaii and Florida), Barbados, and Japan, both spatially and temporally. (2) All fossil specimens of the family have been found preserved in amber, which might be due to the small size of the specimens that prevents their discovery in other types of deposits. However, we here add a second aspect, namely the occurrence of this cryptic and currently scarce family of beetles in resinous environments, where they live in relationship with resin-producing trees. (3) The discovery of a new specimen from a family unknown on the African continent supports the relevance of these younger resins in preserving arthropods that lived in pre-Anthropocene times. Although we cannot demonstrate their extinction in the region, since it is possible that the family still survives in the already fragmented coastal forests of East Africa, we are detecting a loss of local biodiversity during the so-called Anthropocene, probably due to human activity.

Three-dimensional analyses of vascular network morphology in a murine lymph node by X-ray phase-contrast tomography with a 2D Talbot array.

With growing molecular evidence for correlations between spatial arrangement of blood vasculature and fundamental immunological functions, carried out in distinct compartments of the subdivided lymph node, there is an urgent need for three-dimensional models that can link these aspects. We reconstructed such models at a 1.84 µm resolution by the means of X-ray phase-contrast imaging with a 2D Talbot array in a short time without any staining. In addition reconstructions are verified in immunohistochemistry staining as well as in ultrastructural analyses. While conventional illustrations of mammalian lymph nodes depict the hilus as a definite point of blood and lymphatic vessel entry and exit, our method revealed that multiple branches enter and emerge from an area that extends up to one third of the organ's surface. This could be a prerequisite for the drastic and location-dependent remodeling of vascularization, which is necessary for lymph node expansion during inflammation. Contrary to corrosion cast studies we identified B-cell follicles exhibiting a two times denser capillary network than the deep cortical units of the T-cell zone. In addition to our observation of high endothelial venules spatially surrounding the follicles, this suggests a direct connection between morphology and B-cell homing. Our findings will deepen the understanding of functional lymph node composition and lymphocyte migration on a fundamental basis.

Genomic-Phenomic Reciprocal Illumination: Desyopone hereon gen. et sp. nov., an Exceptional Aneuretine-like Fossil Ant from Ethiopian Amber (Hymenoptera: Formicidae: Ponerinae).

Fossils are critical for understanding the evolutionary diversification, turnover, and morphological disparification of extant lineages. While fossils cannot be sequenced, phenome-scale data may be generated using micro-computed tomography (µ-CT), thus revealing hidden structures and internal anatomy, when preserved. Here, we adduce the male caste of a new fossil ant species from Miocene Ethiopian amber that resembles members of the Aneuretinae, matching the operational definition of the subfamily. Through the use of synchrotron radiation for µ-CT, we critically test the aneuretine-identity hypothesis. Our results indicate that the new fossils do not belong to the Aneuretinae, but rather the Ponerini (Ponerinae). Informed by recent phylogenomic studies, we were able to place the fossils close to the extant genus Cryptopone based on logical character analysis, with the two uniquely sharing absence of the subpetiolar process among all ponerine genera. Consequently, we: (1) revise the male-based key to the global ant subfamilies; (2) revise the definitions of Aneuretinae, Ponerinae, Platythyreini, and Ponerini; (3) discuss the evolution of ant mandibles; and (4) describe the fossils as †Desyopone hereon gen. et sp. nov. Our study highlights the value of males for ant systematics and the tremendous potential of phenomic imaging technologies for the study of ant evolution.

Multiscale analysis on otolith structural features reveals differences in ontogenesis and sex in Merluccius merluccius in the western Adriatic Sea.

Otolith biomineralization results from biochemical processes regulated by the interaction of internal (physiological) and external (environmental) factors which lead to morphological and ultrastructural variability at intra- and interspecific levels. The aim of this study was to conduct a multi-scale analysis of the sagittal otoliths of the Merlucius merlucius (European hake) from the western Adriatic Sea in order to correlate otolith features with fish ontogeny and sex. We show that otoliths of sexually undifferentiated (non-sexed) individuals having a fish body total length (TL) less than 15 cm had faster growth in length, width, area, perimeter, volume and weight and a higher amount of organic matrix compared with otoliths of sexually differentiated individuals (females and males) having a fish size range of 15-50 cm. Most importantly, with increasing fish TL, female saccular otoliths contained a higher number of protuberances and rougher surface compared with male specimens, which showed more uniform mean curvature density. The differences between females and males discovered in this study could be associated with fish hearing adaptation to reproductive behavioural strategies during the spawning season. The outcomes of this research provide insights on how size and sex-related variations in otolith features may be affected by fish ecological and behavioural patterns.

The first fossil immature of Elmidae: an unusual riffle beetle larva preserved in Baltic amber.

Elmidae, riffle beetles, have both adult and immature stages that show specializations for water environments. Fossils of adults of Elmidae are already known from amber, however a record of immatures was so far lacking. We report here the first fossil larva of Elmidae, preserved in Baltic amber. To be able to access details of the body hidden by inclusions and "Verlumung" we conducted, in addition to optical documentation methods, micro-CT and synchrotron documentation methods. The larva is characterised by prominent dorso-lateral and lateral processes and a plate-like ventral operculum at the end of the abdomen. The new fossil has similarities in the general body shape and the prominent characters with some modern larvae of Elmidae. The posterior protrusions on the trunk end possibly represent gills, which would imply that fossil larvae of Elmidae also led a water-related life style similar to modern representatives.

A previously unknown feeding mode in millipedes and the convergence of fluid feeding across arthropods.

We report fluid feeding with a sucking pump in the arthropod class Diplopoda, using a combination of synchrotron tomography, histology, electron microscopy, and three-dimensional reconstructions. Within the head of nine species of the enigmatic Colobognatha, we found a pumping chamber, which acts as positive displacement pump and is notably similar to that of insects, showing even fine structural convergences. The sucking pump of these millipedes works together with protractible mouthparts and externally secreted saliva for the acquisition of liquid food. Fluid feeding is one of the great evolutionary innovations of terrestrial arthropods, and our study suggests that it evolved with similar biomechanical solutions convergent across all major arthropod taxa. While fluid-feeding insects are megadiverse today, it remains unclear why other lineages, such as Colobognatha, are comparably species poor.

The velvet worm brain unveils homologies and evolutionary novelties across panarthropods.

BACKGROUND: The evolution of the brain and its major neuropils in Panarthropoda (comprising Arthropoda, Tardigrada and Onychophora) remains enigmatic. As one of the closest relatives of arthropods, onychophorans are regarded as indispensable for a broad understanding of the evolution of panarthropod organ systems, including the brain, whose anatomical and functional organisation is often used to gain insights into evolutionary relations. However, while numerous recent studies have clarified the organisation of many arthropod nervous systems, a detailed investigation of the onychophoran brain with current state-of-the-art approaches is lacking, and further inconsistencies in nomenclature and interpretation hamper its understanding. To clarify the origins and homology of cerebral structures across panarthropods, we analysed the brain architecture in the onychophoran Euperipatoides rowelli by combining X-ray micro-computed tomography, histology, immunohistochemistry, confocal microscopy, and three-dimensional reconstruction. RESULTS: Here, we use this detailed information to generate a consistent glossary for neuroanatomical studies of Onychophora. In addition, we report novel cerebral structures, provide novel details on previously known brain areas, and characterise further structures and neuropils in order to improve the reproducibility of neuroanatomical observations. Our findings support homology of mushroom bodies and central bodies in onychophorans and arthropods. Their antennal nerve cords and olfactory lobes most likely evolved independently. In contrast to previous reports, we found no evidence for second-order visual neuropils, or a frontal ganglion in the velvet worm brain. CONCLUSION: We imaged the velvet worm nervous system at an unprecedented level of detail and compiled a comprehensive glossary of known and previously uncharacterised neuroanatomical structures to provide an in-depth characterisation of the onychophoran brain architecture. We expect that our data will improve the reproducibility and comparability of future neuroanatomical studies.

Profiling cellular diversity in sponges informs animal cell type and nervous system evolution.

The evolutionary origin of metazoan cell types such as neurons and muscles is not known. Using whole-body single-cell RNA sequencing in a sponge, an animal without nervous system and musculature, we identified 18 distinct cell types. These include nitric oxide­sensitive contractile pinacocytes, amoeboid phagocytes, and secretory neuroid cells that reside in close contact with digestive choanocytes that express scaffolding and receptor proteins. Visualizing neuroid cells by correlative x-ray and electron microscopy revealed secretory vesicles and cellular projections enwrapping choanocyte microvilli and cilia. Our data show a communication system that is organized around sponge digestive chambers, using conserved modules that became incorporated into the pre- and postsynapse in the nervous systems of other animals.

Coming together-symbiont acquisition and early development in deep-sea bathymodioline mussels.

How and when symbionts are acquired by their animal hosts has a profound impact on the ecology and evolution of the symbiosis. Understanding symbiont acquisition is particularly challenging in deep-sea organisms because early life stages are so rarely found. Here, we collected early developmental stages of three deep-sea bathymodioline species from different habitats to identify when these acquire their symbionts and how their body plan adapts to a symbiotic lifestyle. These mussels gain their nutrition from chemosynthetic bacteria, allowing them to thrive at deep-sea vents and seeps worldwide. Correlative imaging analyses using synchrotron-radiation based microtomography together with light, fluorescence and electron microscopy revealed that the pediveliger larvae were aposymbiotic. Symbiont colonization began during metamorphosis from a planktonic to a benthic lifestyle, with the symbionts rapidly colonizing first the gills, the symbiotic organ of adults, followed by all other epithelia of their hosts. Once symbiont densities in plantigrades reached those of adults, the host's intestine changed from the looped anatomy typical for bivalves to a straightened form. Within the Mytilidae, this morphological change appears to be specific to Bathymodiolus and Gigantidas, and is probably linked to the decrease in the importance of filter feeding when these mussels switch to gaining their nutrition largely from their symbionts.

Juvenile ecology drives adult morphology in two insect orders.

Most animals undergo ecological niche shifts between distinct life phases, but such shifts can result in adaptive conflicts of phenotypic traits. Metamorphosis can reduce these conflicts by breaking up trait correlations, allowing each life phase to independently adapt to its ecological niche. This process is called adaptive decoupling. It is, however, yet unknown to what extent adaptive decoupling is realized on a macroevolutionary scale in hemimetabolous insects and if the degree of adaptive decoupling is correlated with the strength of ontogenetic niche shifts. It is also unclear whether the degree of adaptive decoupling is correlated with phenotypic disparity. Here, we quantify nymphal and adult trait correlations in 219 species across the whole phylogeny of earwigs and stoneflies to test whether juvenile and adult traits are decoupled from each other. We demonstrate that adult head morphology is largely driven by nymphal ecology, and that adult head shape disparity has increased with stronger ontogenetic niche shifts in some stonefly lineages. Our findings implicate that the hemimetabolan metamorphosis in earwigs and stoneflies does not allow for high degrees of adaptive decoupling, and that high phenotypic disparity can even be realized when the evolution of distinct life phases is coupled.

Integrative anatomical study of the branched annelid Ramisyllis multicaudata (Annelida, Syllidae).

The sponge-dwelling Syllidae Ramisyllis multicaudata and Syllis ramosa are the only annelid species for which a branched body with one head and multiple posterior ends is known. In these species, the head is located deep within the sponge, and the branches extend through the canal system of their host. The morphology of these creatures has captivated annelid biologists since they were first discovered in the late XIXth century, and their external characteristics have been well documented. However, how their branched bodies fit within their symbiotic host sponges and how branches translate into internal anatomy has not been documented before. These features are crucially relevant for understanding the body of these animals, and therefore, the aim of this study was to investigate these aspects. In order to assess these questions, live observation, as wells as histology, immunohistochemistry, micro-computed tomography, and transmission electron microscopy techniques were used on specimens of R. multicaudata. By using these techniques, we show that the complex body of R. multicaudata specimens extends greatly through the canal system of their host sponges. We demonstrate that iterative external bifurcation of the body is accompanied by the bifurcation of the longitudinal organ systems that are characteristic of annelids. Additionally, we also highlight that the bifurcation process leaves an unmistakable fingerprint in the form of newly-described "muscle bridges." These structures theoretically allow one to distinguish original and derived branches at each bifurcation. Last, we characterize some of the internal anatomical features of the stolons (reproductive units) of R. multicaudata, particularly their nervous system. Here, we provide the first study of the internal anatomy of a branched annelid. This information is not only crucial to deepen our understanding of these animals and their biology, but it will also be key to inform future studies that try to explain how this morphology evolved.

Estimation of sinking velocity using free-falling dynamically scaled models: Foraminifera as a test case.

The velocity of settling particles is an important determinant of distribution in extinct and extant species with passive dispersal mechanisms, such as plants, corals and phytoplankton. Here, we adapted dynamic scaling, borrowed from engineering, to determine settling velocity. Dynamic scaling leverages physical models with relevant dimensionless numbers matched to achieve similar dynamics to the original object. Previous studies have used flumes, wind tunnels or towed models to examine fluid flow around objects with known velocities. Our novel application uses free-falling models to determine the unknown sinking velocity of planktonic Foraminifera - organisms important to our understanding of the Earth's current and historic climate. Using enlarged 3D printed models of microscopic Foraminifera tests, sunk in viscous mineral oil to match their Reynolds numbers and drag coefficients, we predicted sinking velocity of real tests in seawater. This method can be applied to study other settling particles such as plankton, spores or seeds.