Exceptional preservation of internal organs in a new fossil species of freshwater shrimp (Caridea: Palaemonoidea) from the Eocene of Messel (Germany).

A new species of extinct freshwater shrimp was discovered in the Eocene deposit of the Messel Pit Konservat-Lagerstätte. This rare find is represented by only a few specimens, one of which showing exceptionally preserved soft tissues and other internal parts like the stomach with possibly gastric ossicles in place, branchiae, the ovary, and the left mandible, never described in a fossil shrimp. The new species Bechleja brevirostris n. sp. is characterized by a short rostrum bearing 6-8 dorsal spines and one ventral tooth, and long second pereiopods with strong chelae. One additional specimen shows a slightly different morphology and might belong to a different species. The systematic position of the species among the superfamily Palaemonoidea is discussed, as well as implications for the knowledge of the paleoenvironment of Lake Messel and the paleobiogeography of the Eocene.

Bizarre morphology in extinct Eocene bugs (Heteroptera: Pentatomidae).

Newly discovered fossil bugs (Insecta: Hemiptera: Heteroptera: Pentatomidae) from the Eocene of Messel (Germany) and Green River (North America) exhibit an exaggerated morphology including prominent spiny humeral and anterolateral angles of the pronotum and a spiny lateral abdominal margin. Especially the humeral angles are unique; they consist of expansive, rounded projections with strong spines, which is a rare trait among pentatomids. A hypothesis for the function of this extreme morphology is defence against small vertebrate predators, such as birds or reptiles. The same protuberances also produce a disruptive effect camouflaging the specimen in its environment and provide additional protection. Therefore, the extreme morphology provides primary as well as secondary anti-predator defence. The morphology of Eospinosus peterkulkai gen. et sp. nov. and E. greenriverensis sp. nov. resembles that of Triplatygini, which today occur exclusively in Madagascar, as well as that of Discocephalinae or Cyrtocorinae, which today occur in the Neotropics. Due to a lack of conclusive characters, it cannot be excluded that the fossil species may represent a case of remarkable convergence and are not related to either taxon. Phylogenetic analyses using parsimony as well as Bayesian algorithms confirmed that the new genus is a member of Pentatomidae, but could not solve its phylogenetic relationships within Pentatomidae.

How to extract and analyze pollen from internal organs and exoskeletons of fossil insects?

This protocol explains how to extract pollen from fossil insects with subsequent descriptions of pollen treatment. We also describe how to document morphological and ultrastructural features with light-microscopy and electron microscopy. It enables a taxonomic assignment of pollen that can be used to interpret flower-insect interactions, foraging and feeding behavior of insects, and the paleoenvironment. The protocol is limited by the state of the fossil, the presence/absence of pollen on fossil specimens, and the availability of extant pollen for comparison. For complete details on the use and execution of this protocol, please refer to Wappler et al. (2015), Ulrich and Grímsson (2020), and Wedmann et al. (2021).

A Revision of fossil Bibionidae (Insecta: Diptera) from the Oligocene of Germany.

We revise the available material of fossil Bibionidae from the Oligocene of Germany, except for the Early Oligocene site of Kleinkems which has recently been revised. The bulk of the material originates from the Late Oligocene Lagerstätten of Rott and Enspel. One new species, Bibio castaneipennis sp.n., is described from Enspel. The following new combinations are established: Hesperinus heeri (Heyden Heyden, 1865) comb.n. (previously Plecia heeri), Plecia dubia (Germar, 1837) (previously Phthiria dubia). Plecia collossea (Heyden Heyden, 1865) is removed from synonymy with Plecia morio (Heer, 1849), Plecia gracilenta (Heyden Heyden, 1865) is removed from synonymy with Plecia lygaeoides (Heer, 1849). The following new synonymies are established: Plecia elegantula Meunier, 1915 = Penthetria rottensis Statz, 1943 = Penthetria scita Statz, 1943 = Hesperinus heeri (Heyden Heyden, 1865); Plecia superba Meunier, 1915 = Plecia imperialis Statz, 1943 = Plecia philippi Statz, 1943 = Plecia collossea (Heyden Heyden, 1865); Helophilus primarius Germar, 1837 = Plecia abava (Heyden Heyden, 1865) = Plecia satyrus Statz, 1943 = Plecia dubia (Germar, 1837); Plecia expositia (Heyden Heyden, 1865) = Plecia grandaeva (Heyden Heyden, 1865) = Plecia antenata (Heyden Heyden, 1865) = Plecia elongata (Heyden Heyden, 1865) = Plecia pulchella Meunier, 1915 = Plecia hypogaea (Heyden Heyden, 1865); Plecia schineri (Heyden Heyden, 1865) = Plecia macrocephala (Heyden Heyden, 1865); Plecia lapidaria (Heyden Heyden, 1865) = Bibio brachypteroides Meunier, 1915 = Plecia vulpina Statz, 1943 = Plecia pinguis (Heyden Heyden, 1865); Plecia lapidaria nigra Statz, 1943 = Plecia sluiteri Meunier, 1917; Plecia veterana (Heyden Heyden, 1865) = Plecia stygia (Heyden Heyden, 1865); Bibio spadicea Statz, 1943 = Bibio aerosus Statz, 1943; Bibio heydeni Meunier, 1920 = Bibio comosella Statz, 1943 = Bibio germari Meunier, 1920; Plecia heroica Heyden Heyden, 1865 = Bibio giganteus Unger, 1841; Bibio infumatus Meunier, 1915 = Bibio mimas L. Heyden, 1870. The following names are placed as nomina dubia pending rediscovery of the type material: Plecia volgeri (C.H.G. Heyden, 1859); Bibio janus L. Heyden, 1870; Bibio tertiarius C.H.G. Heyden, 1862; Dilophus deletus (C.H.G. Heyden, 1862). The male morphotypes described but not formally named by Statz (1943) are tentatively assigned to named species.

The last meal of an Eocene pollen-feeding fly.

One of the most important trophic interactions today is that between insects and their floral hosts. This biotic association is believed to have been critical to the radiation of flowering plants and many pollinating insect lineages over the last 120 million years (Ma). Trophic interactions among fossil organisms are challenging to study, and most inferences are based on indirect evidence. Fossil records providing direct evidence for pollen feeding, i.e., fossil stomach and gut contents, are exceptionally rare.1,2 Such records have the potential to provide information on aspects of animal behavior and ecology as well as plant-animal interactions that are sometimes not yet recognized for their extant relatives. The dietary preferences of short-proboscid nemestrinids are unknown, and pollinivory has not been recorded for extant Nemestrinidae.3 We analyzed the contents of the conspicuously swollen abdomen of an ca. 47.5 Ma old nemestrinid fly of the genus Hirmoneura from Messel, Germany, with photogrammetry and state-of-the-art palynological methods. The fly fed on pollen from at least four plant families-Lythraceae, Vitaceae, Sapotaceae, and Oleaceae-and presumably pollinated flowers of two extant genera, Decodon and Parthenocissus. We interpret the feeding and foraging behavior of the fly, reconstruct its preferred habitat, and conclude about its pollination role and importance in paratropical environments. This represents the first evidence that short-proboscid nemestrinid flies fed, and possibly feed to this day, on pollen, demonstrating how fossils can provide vital information on the behavior of insects and their ecological relationships with plants.

Eco-morphological diversity of larvae of soldier flies and their closest relatives in deep time.

Stratiomyomorpha (soldier flies and allies) is an ingroup of Diptera, with a fossil record stretching back to the Early Cretaceous (the Barremian, about 125 MYA). Stratiomyomorpha includes at least 3,000 species in the modern fauna, with many species being crucial for ecosystem functions, especially as saprophages. Larvae of many stratiomyomorphans are especially important as scavengers and saproxyls in modern ecosystems. Yet, fossil larvae of the group are extremely scarce. Here we present 23 new records of fossil stratiomyomorphan larvae, representing six discrete morphotypes. Specimens originate from Cretaceous amber from Myanmar, Eocene Baltic amber, Miocene Dominican amber, and compression fossils from the Eocene of Messel (Germany) and the Miocene of Slovenia. We discuss the implications of these new records for our understanding of stratiomyomorphan ecomorphology in deep time as well as their palaeoecology.

Seven remarkable new fossil species of parasitoid wasps (Hymenoptera, Ichneumonidae) from the Eocene Messel Pit.

Parasitoid wasps of the family Ichneumonidae are one of the most diverse and species-rich groups of organisms with a worldwide distribution. We here describe seven new ichneumonid fossil species and two new genera from a remarkable insect fossil site, the Eocene Messel Pit in Germany (~47Ma). The unique fossil preservation allows us to place five out of the seven new species unequivocally in extant subfamilies and genera. For the first time, lobed claws which are a clear synapomorphy for the subfamily Pimplinae, are observed in a fossil, making the newly described Scambus fossilobus sp. nov. the oldest unequivocal representative of the group. We also describe a fossil of Labeninae (Trigonator macrocheirus gen. et sp. nov.), an ichneumonid subfamily that was until now believed to be an exclusively Gondwanan element. Furthermore, the newly described Rhyssella vera sp. nov., Xanthopimpla messelensis sp. nov., and X. praeclara sp. nov. provide evidence that these extant genera date back as far as the Early/Middle Eocene. In contrast to the clear placement of most of the newly described species, we were unable to place Polyhelictes bipolarus gen. et sp. nov. and Mesornatus markovici gen. et sp. nov. in an ichneumonid subfamily, mostly due to the high levels of homoplasy found in this group. These findings on the one hand demonstrate the need for a more rigorous approach in the taxonomic placement of fossil ichneumonids, and on the other hand provide more precise minimum ages for several ichneumonid genera and subfamilies.

A new genus of Hemerobiidae (Neuroptera) from Baltic amber, with a critical review of the Cenozoic Megalomus-like taxa and remarks on the wing venation variability of the family.

A new genus and two new species of Hemerobiidae (Neuroptera) are described from the late Eocene Baltic amber, i.e., Proneuronema gradatum gen. et sp. nov. and P. minor gen. et sp. nov. Several Early Eocene species (mostly unnamed) from Europe and North America are also considered to belong to this genus, including Proneuronema wehri (Makarkin et al., 2003), comb. nov. The new genus is probably most closely related to the extant genus Neuronema McLachlan, 1869, and therefore assigned to Drepanepteryginae. A critical review of Cenozoic taxa of the Megalomus-like hemerobiids is provided. Prophlebonema Krüger, 1923 is considered as a new subjective synonym of Drepanepteryx Leach, 1815. Plesiorobius Klimaszewski et Kevan, 1986 from the Late Cretaceous is considered as belonging to Hemerobiidae. It is noted that wing venation variability in species of Hemerobiidae (including these fossils) is high. Some of their venational abnormalities (anomalies) may have phylogenetic implications.

Spongillaflies (Neuroptera, Sisyridae) in Baltic amber.

Two spongillaflies species are described and illustrated from Eocene Baltic amber: Paleosisyra minor n. sp. and Paleosisyra electrobaltica Wichard et al., 2009; the latter species was described based on a female and is now re-described in consideration of the male genitalia of two new male specimens. Extant Sisyridae comprise few species, and their fossil record is very scarce.

Morphological and behavioral convergence in extinct and extant bugs: the systematics and biology of a new unusual fossil lace bug from the eocene.

The bug Gyaclavator kohlsi Wappler, Guilbert, Wedmann et Labandeira, gen. et sp. nov., represents a new extinct genus of lace bugs (Insecta: Heteroptera: Tingidae) occurring in latest early Eocene deposits of the Green River Formation, from the southern Piceance Basin of Northwestern Colorado, in North America. Gyaclavator can be placed within the Tingidae with certainty, perhaps it is sistergroup to Cantacaderinae. If it belongs to Cantacaderinae, it is the first fossil record of this group for North America. Gyaclavator has unique, conspicuous antennae bearing a specialized, highly dilated distiflagellomere, likely important for intra- or intersex reproductive competition and attraction. This character parallels similar antennae in leaf-footed bugs (Coreidae), and probably is associated with a behavioral convergence as well.

New Palaeogene horntail wasps (Hymenoptera, Siricidae) and a discussion of their fossil record.

The phylogenetic placement of siricid hymenopterans and especially the relationships among Siricidae are not resolved, and are in need of further investigation. The fossil record helps to illuminate the evolutionary history of this group. In this paper, Xoanon? eocenicus sp. nov. is newly described from the Eocene Fossillagerstätte Grube Messel (Germany). Although several characters of the wing venation of this fossil are similar to the extant genus Xoanon, there remain some doubts concerning the generic placement. A newly found fossil is attributed to Urocerus ligniticus (Piton, 1940) from the Paloecene Fossillagerstätte Menat (France) and provides more morphological information on this species. An overview of the fossil record of Siricidae in the strict sense is given and the state of knowledge on the different fossils is reviewed.

First record of the family Ithonidae (Neuroptera) from Baltic amber.

Elektrithone expectata gen. et sp. nov. (Neuroptera: Ithonidae) is described from Eocene Baltic amber and represents the first record of this family from Baltic amber. The forewing venation of the new genus is characterized by a small number of crossveins as found in some 'polystoechotid'-like genera, and by the absence of the distal nygma and the strong reduction of the anal area which are characteristic of 'rapismatid'-like ithonids.

First fossil larvae of Berothidae (Neuroptera) from Baltic amber, with notes on the biology and termitophily of the family.

Four fossil larvae of Berothidae (Neuroptera) from Baltic amber are described in detail, and the main characters of a fifth larva are discussed briefly. Two first instars very probably belong to the Berothinae; the subfamilial affinities of three othe (probably full-grown) larvae are unclear. The latter are characterized by features not found so far in extant taxa of Berothi dae: antennae and labial palps with six to seven segments; ecdysial cleavage lines consist of only frontal and coronal sutures (the lateral suture is absent); pronotal sclerites large and very close to each other along midline. However, these larvae belong with certainty to Berothidae as indicated by the structure of their mouthparts, and their general appearance. Morphological and biological data on the larvae of Berothidae are summarized and analyzed. It is presumed that termitophily might have evolved during the Cretaceous (or in the early Cenozoic), and only in Berothinae (or in subfamilies closely related to this group). The Baltic amber berothid assemblage apparently included both termitophilous and noni termitophilous larvae.

Phylogeographic analysis elucidates the influence of the ice ages on the disjunct distribution of relict dragonflies in Asia.

Unusual biogeographic patterns of closely related groups reflect events in the past, and molecular analyses can help to elucidate these events. While ample research on the origin of disjunct distributions of different organism groups in the Western Paleartic has been conducted, such studies are rare for Eastern Palearctic organisms. In this paper we present a phylogeographic analysis of the disjunct distribution pattern of the extant species of the strongly cool-adapted Epiophlebia dragonflies from Asia. We investigated sequences of the usually more conserved 18 S rDNA and 28 S rDNA genes and the more variable sequences of ITS1, ITS2 and CO2 of all three currently recognised Epiophlebia species and of a sample of other odonatan species. In all genes investigated the degrees of similarity between species of Epiophlebia are very high and resemble those otherwise found between different populations of the same species in Odonata. This indicates that substantial gene transfer between these populations occurred in the comparatively recent past. Our analyses imply a wide distribution of the ancestor of extant Epiophlebia in Southeast Asia during the last ice age, when suitable habitats were more common. During the following warming phase, its range contracted, resulting in the current disjunct distribution. Given the strong sensitivity of these species to climatic parameters, the current trend to increasing global temperatures will further reduce acceptable habitats and seriously threaten the existences of these last representatives of an ancient group of Odonata.

Fossilized biophotonic nanostructures reveal the original colors of 47-million-year-old moths.

Structural colors are generated by scattering of light by variations in tissue nanostructure. They are widespread among animals and have been studied most extensively in butterflies and moths (Lepidoptera), which exhibit the widest diversity of photonic nanostructures, resultant colors, and visual effects of any extant organism. The evolution of structural coloration in lepidopterans, however, is poorly understood. Existing hypotheses based on phylogenetic and/or structural data are controversial and do not incorporate data from fossils. Here we report the first example of structurally colored scales in fossil lepidopterans; specimens are from the 47-million-year-old Messel oil shale (Germany). The preserved colors are generated by a multilayer reflector comprised of a stack of perforated laminae in the scale lumen; differently colored scales differ in their ultrastructure. The original colors were altered during fossilization but are reconstructed based upon preserved ultrastructural detail. The dorsal surface of the forewings was a yellow-green color that probably served as a dual-purpose defensive signal, i.e. aposematic during feeding and cryptic at rest. This visual signal was enhanced by suppression of iridescence (change in hue with viewing angle) achieved via two separate optical mechanisms: extensive perforation, and concave distortion, of the multilayer reflector. The fossils provide the first evidence, to our knowledge, for the function of structural color in fossils and demonstrate the feasibility of reconstructing color in non-metallic lepidopteran fossils. Plastic scale developmental processes and complex optical mechanisms for interspecific signaling had clearly evolved in lepidopterans by the mid-Eocene.

Direct and indirect fossil records of megachilid bees from the Paleogene of Central Europe (Hymenoptera: Megachilidae).

Aside from pollen and nectar, bees of the subfamily Megachilinae are closely associated with plants as a source of materials for nest construction. Megachilines use resins, masticated leaves, trichomes and other plant materials sometimes along with mud to construct nests in cavities or in soil. Among these, the leafcutter bees (Megachile s.l.) are the most famous for their behaviour to line their brood cells with discs cut from various plants. We report on fossil records of one body fossil of a new non-leafcutting megachiline and of 12 leafcuttings from three European sites-Eckfeld and Messel, both in Germany (Eocene), and Menat, France (Paleocene). The excisions include the currently earliest record of probable Megachile activity and suggest the presence of such bees in the Paleocene European fauna. Comparison with extant leafcuttings permits the interpretation of a minimal number of species that produced these excisions. The wide range of size for the leafcuttings indirectly might suggest at least two species of Megachile for the fauna of Messel in addition to the other megachiline bee described here. The presence of several cuttings on most leaves from Eckfeld implies that the preferential foraging behaviour of extant Megachile arose early in megachiline evolution. These results demonstrate that combined investigation of body and trace fossils complement each other in understanding past biodiversity, the latter permitting the detection of taxa not otherwise directly sampled and inferences on behavioural evolution.

The first fossil leaf insect: 47 million years of specialized cryptic morphology and behavior.

Stick and leaf insects (insect order Phasmatodea) are represented primarily by twig-imitating slender forms. Only a small percentage ( approximately 1%) of extant phasmids belong to the leaf insects (Phylliinae), which exhibit an extreme form of morphological and behavioral leaf mimicry. Fossils of phasmid insects are extremely rare worldwide. Here we report the first fossil leaf insect, Eophyllium messelensis gen. et sp. nov., from 47-million-year-old deposits at Messel in Germany. The new specimen, a male, is exquisitely preserved and displays the same foliaceous appearance as extant male leaf insects. Clearly, an advanced form of extant angiosperm leaf mimicry had already evolved early in the Eocene. We infer that this trait was combined with a special behavior, catalepsy or "adaptive stillness," enabling Eophyllium to deceive visually oriented predators. Potential predators reported from the Eocene are birds, early primates, and bats. The combination of primitive and derived characters revealed by Eophyllium allows the determination of its exact phylogenetic position and illuminates the evolution of leaf mimicry for this insect group. It provides direct evidence that Phylliinae originated at least 47 Mya. Eophyllium enlarges the known geographical range of Phylliinae, currently restricted to southeast Asia, which is apparently a relict distribution. This fossil leaf insect bears considerable resemblance to extant individuals in size and cryptic morphology, indicating minimal change in 47 million years. This absence of evolutionary change is an outstanding example of morphological and, probably, behavioral stasis.