Amber Research Articles

Rogue sawflies: rare late Eocene amber fossils provide new calibration points for dating the evolution of Tenthredinoidea (Insecta: Hymenoptera)

True sawflies (Tenthredinoidea) have a substantial fossil record but are rarely encountered in Eocene ambers. Here we describe three new taxa in this superfamily from late Eocene ambers. †Rovnotaxonus aristovi gen. et sp. nov. is the first true sawfly reported from Rovno amber. Based primarily on characters in the fore wing venation, we assign the new taxon to Tenthredinidae: Allantinae: Allantini. We also describe two new species of Diprionidae from Baltic amber: †Eodiprion pectinatus sp. nov. from a female specimen and †Monodiprion gladius gen. et sp. nov. from a male previously reported as †Eodiprion sp. by Schedl (2008); we redescribe †Eodiprion Schedl, 2007 and provide emended diagnoses of the genus and of †Eodiprion groehni Schedl, 2007. We integrate all these fossils as well as †Sambia Vilhelmsen and Engel, 2012 (Tenthredinidae: Tenthredininae) previously described from Baltic amber in a combined data set assembled from previously published morphological and molecular data sets. We analyse the combined data set in a Bayesian framework and implement RoguePlots to evaluate the positions of the fossils. The diprionid fossils are unequivocally placed inside Diprionidae, in a polytomy with extant members of Diprioninae; the Monocteninae, the other subfamily currently recognized in the family, is not retrieved as monophyletic. †Rovnotaxonus is placed inside Allantinae and shares some characters with Taxonus. †Sambia is placed near the base of Tenthredininae. The evaluation of the phylogenetic position of the fossils treated here will make them available for future dating analyses of Tenthredinoidea, helping to further elucidate the evolutionary history of this significant lineage of herbivorous insects. Possible reasons for the comparatively low abundance of true sawflies in late Eocene ambers are discussed. http://zoobank.org/urn:lsid:zoobank.org:pubF2095774-CF02-4851-8D73-250B5718EF6F.

First Australian amber fossil of Podonominae (Diptera: Chironomidae) from the late Middle Eocene

A non-biting midge of the cosmopolitan family Chironomidae (Podonominae) is recorded in amber from the Anglesea Coal Measures, southeastern Australia. The new morphotype is likely a new species but is not formally described here because of insufficient diagnostic character states. To date, only five amber deposits in the Northern Hemisphere have yielded fossils of Podonominae, making our discovery the first amber-hosted representative of the group from the Southern Hemisphere. The single adult male individual has been assigned to the subfamily Podonominae, and shows similarities to the Austrochlus cluster group including small size, the lack of veins R2 + 3, and the distally located cross-vein m-cu. Synchrotron X-ray microtomographic imaging reveals some internal structures of the wing musculature and brain capsule, highlighting the taphonomic significance of this unique specimen. Maria Blake* [ maria.paulsen@monash.edu ], School of Earth, Atmosphere and Environment, 9 Rainforest Walk, Monash University, Clayton, Victoria, 3800, Australia Enrique Peñalver [ e.penalver@igme.es ], Instituto Geológico y Minero de España, CSIC, Valencia, Spain Jeffrey D. Stilwell [ jeffrey.stilwell@monash.edu ], School of Earth, Atmosphere and Environment, 9 Rainforest Walk, Monash University, Clayton, Victoria, 3800, Australia, and Australian Museum, Australian Museum, 1 William Street, Sydney, NSW 2010, Australia Joseph J. Bevitt [ jbv@ansto.gov.au ], Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia Daniel J. Bickel [ Dan.Bickel@australian.museum ] Australian Museum, 1 William Street, Sydney, New South Wales, 2000, Australia.

New species and reclassification of the fossil assassin bug Koenigsbergia (Hemiptera: Reduviidae: Phimophorinae)

The assassin bug genus Koenigsbergia Popov, 2003 is currently monotypic and represented by a female holotype from Baltic Amber (~33.9–55.8 MYA). The genus was originally described within Phymatinae (Phymatine Complex or phymatine clade). However, our literature review reveals that the amber fossil likely belongs to the subfamily Phimophorinae, which is distantly related to the phymatine clade. The recent acquisition of one male and one nymph of Koenigsbergia provides the opportunity to reevaluate the systematic placement of this genus. We here examine the new fossils, concluding that the adult male represents an undescribed species, and describe it as Koenigsbergia explicativa, new species. Our morphological comparison between Phimophorinae, Phymatinae, and Koenigsbergia (macro imagining, scanning electron microscopy) shows that the fossil genus shares notable similarities with Phimophorus Bergroth, 1886 and Mendanocoris Miller, 1956. We therefore formally transfer the fossil genus to Phimophorinae.

The First Cretaceous Epyrine Wasp (Hymenoptera: Bethylidae): A New Genus and Species from Early Cenomanian Kachin Amber.

The Epyrinae are the second largest subfamily of Bethylidae and the most diverse in the fossil record. However, although six of the nine bethylid subfamilies are known during the Cretaceous (either as compression or amber fossils), the Epyrinae were hitherto unknown before the lower Eocene. In this contribution, we report the discovery of the oldest member of this group, based on a female specimen from the early Cenomanian amber of Kachin, Myanmar. We describe and illustrate a new genus and species, Hukawngepyris setosus gen. et sp. nov. The new genus is compared with the other epyrine genera and characterized by a unique combination of characters not known in the subfamily. Hukawngepyris setosus gen. et sp. nov. is especially unique in the configuration of the forewing venation, with a complete 2r-rs&Rs vein, curved towards the anterior wing margin, and the presence of three proximal and three distal hamuli. The key to the genera of Epyrinae is accommodated to include the newly erected genus.

Ant evolution: Amber revelations of extinction, survival and recovery

Ant fossils from the Cretaceous are rare but critical for understanding the early evolution of this incredibly successful group of animals. New amber fossils fill important gaps, revealing patterns of death, survival, and radiation around the end Cretaceous extinction.

Tannoura: A new early Barremian fossiliferous amber outcrop from South Lebanon

A fossiliferous amber outcrop in Tannoura (Rashayya District, Southern Lebanon) is described. This new discovery constitutes the 30th amber outcrop with biological inclusions in Lebanon and enriches and improves our knowledge about the palaeobiodiversity and palaeoenvironment of the North-Eastern coast of Gondwana during the early Barremian. Also, an infrared spectrum of the amber from Tannoura is given and discussed.

New Canadian amber deposit fills gap in fossil record near end-Cretaceous mass extinction

Amber preserves an exceptional record of tiny, soft-bodied organisms and chemical environmental signatures, elucidating the evolution of arthropod lineages and the diversity, ecology, and biogeochemistry of ancient ecosystems. However, globally, fossiliferous amber deposits are rare in the latest Cretaceous and surrounding the Cretaceous-Paleogene (K-Pg) mass extinction.1,2,3,4,5 This faunal gap limits our understanding of arthropod diversity and survival across the extinction boundary.2,6 Contrasting hypotheses propose that arthropods were either relatively unaffected by the K-Pg extinction or experienced a steady decline in diversity before the extinction event followed by rapid diversification in the Cenozoic.2,6 These hypotheses are primarily based on arthropod feeding traces on fossil leaves and time-calibrated molecular phylogenies, not direct observation of the fossil record.2,7 Here, we report a diverse amber assemblage from the Late Cretaceous (67.04± 0.16 Ma) of the Big Muddy Badlands, Canada. The new deposit fills a critical 16-million-year gap in the arthropod fossil record spanning the K-Pg mass extinction. Seven arthropod orders and at least 11 insect families have been recovered, making the Big Muddy amber deposit the most diverse arthropod assemblage near the K-Pg extinction. Amber chemistry and stable isotopes suggest the amber was produced by coniferous (Cupressaceae) trees in a subtropical swamp near remnants of the Western Interior Seaway. The unexpected abundance of ants from extant families and the virtual absence of arthropods from common, exclusively Cretaceous families suggests that Big Muddy amber may represent a yet unsampled Late Cretaceous environment and provides evidence of a faunal transition before the end of the Cretaceous.

More than a name: Mid‐Cretaceous amber fossils link crickets and mole crickets (Orthoptera, Ensifera)

AbstractGrylloidea (crickets) and Gryllotalpoidea (mole crickets and ant crickets) are relatively ancient lineages within Orthoptera but their fossil records are not very rich. They are currently considered sister clades within the Gryllidea but with obvious differences in morphology and ecological adaptations. We report a new gryllidean family, †Pseudogryllotalpidae fam. nov. with three new genera and four new species, viz. †Pseudogryllotalpa scalprata gen. et sp. nov., †Unidigitus longialatus gen. et sp. nov., †Petilus zhengi gen. et sp. nov. and †Chunxiania fascia sp. nov. from the mid‐Cretaceous of northern Myanmar (ca. 99 million years ago). Their external and short ovipositors and their modified fossorial forelegs suggest a soil‐inhabiting preference. This new family exhibits a series of ‘intermediate’ character states between Grylloidea and Gryllotalpoidea and seems to be a ‘transitional’ fossil group linking these two superfamilies. This new family was resolved as a sister group of the extant Gryllotalpoidea and provides a new insight into the relationship and evolution of Grylloidea and Gryllotalpoidea.

A new species of the genus Mallecupes (Coleoptera: Cupedidae) from mid-Cretaceous Kachin amber, northern Myanmar

A rare archaic beetle, Mallecupes cheni sp. nov., (Coleoptera: Archostemata: Cupedidae) is described based on a relatively well-preserved specimen from mid-Cretaceous Kachin amber. It is the fifth species of the genus from the same location that can be distinguished from the other 4 congeners based on the combination of rounded temples, laterally produced anterior angles of the pronotum, and extremely large, ovoid window cells in rows 9 and 10. The protective body structures and occupying the wood inhabiting niche resulted in a relatively high diversity of amber fossils of this genus.

Fossils in Myanmar amber demonstrate the diversity of anti-predator strategies of Cretaceous holometabolan insect larvae

Holometabolan larvae are a major part of the animal biomass and an important food source for many animals. Many larvae evolved anti-predator strategies and some of these can even be recognized in fossils. A Lagerstätte known for well-preserved holometabolan larvae is the approximately 100-million-year-old Kachin amber from Myanmar. Fossils can not only allow to identify structural defensive specializations, but also lifestyle and even behavioral aspects. We review here the different defensive strategies employed by various holometabolan larvae found in Kachin amber, also reporting new cases of a leaf-mining hymenopteran caterpillar and a hangingfly caterpillar with extensive spines. This overview demonstrates that already 100 million years ago many modern strategies had already evolved in multiple lineages, but also reveals some cases of now extinct strategies. The repetitive independent evolution of similar strategies in distantly related lineages indicates that several strategies evolved convergently as a result of similar selective pressures.

Independent wing reductions and losses among stick and leaf insects (Phasmatodea), supported by new Cretaceous fossils in amber

BackgroundPhasmatodea (stick and leaf insects) play a central role on the debate regarding wing reduction and loss, and its wings are putative reacquisition from secondarily wingless ancestors based solely on extant species. A pivotal taxon in this respect is the species-poor Timematodea, consisting of approximately 21 wingless extant species, which form the sister group of all remaining winged or wingless stick and leaf insects, the Euphasmatodea.ResultsHerein, the new fossils of Timematodea from mid-Cretaceous Kachin amber are reported, with winged and wingless species co-occurring. The palaeogeographic distributions of all fossils of Holophasmatodea are summarized, showing their wide paleo-distributions. The phylogenetic analysis based on morphological characters confirms the earliest-diverging lineage of winged Breviala cretacea gen. et sp. nov. in Timematodea, and the possible relationships among all families of Holophasmatodea. These are critical for the reconstruction of patterns of wing evolution in early Phasmatodea.ConclusionsThe new fossils suggest that Timematodea once had wings, at least during the mid-Cretaceous. The palaeogeographic occurrences imply that Timematodea probably have been widely distributed since at least the Jurassic. The phylogenetic analysis with the ancestral-state reconstruction of wings indicates that the common ancestors of Holophasmatodea were winged, the reductions and losses of wings among Timematodea and Euphasmatodea have occurred independently since at least the Cretaceous, and the reduction or loss of the forewing earlier than the hind wings.

Parabolitobius antiquus sp. nov., the first Mesozoic amber inclusion of mycetoporine rove beetles (Coleoptera: Staphylinidae: Mycetoporinae)

The rove beetle subfamily Tachyporinae was recently divided into the Tachyporinae and Mycetoporinae subfamilities. Fossil records of mycetoporines are relatively rare, and no Mesozoic amber fossils belonging to this subfamily have been reported. In this study, a new species of the extant Palearctic genus Parabolitobius Li, Zhao & Sakai, 2000, Parabolitobius antiquus sp. nov., is described and illustrated based on a remarkably well-preserved single male adult specimen found in mid-Cretaceous Kachin amber from northern Myanmar. This discovery represents the first Mesozoic amber inclusion of mycetoporine rove beetles and raises the possibility that the genus was widely distributed across Pangea with later global extinction.www.zoobank.org:pub:8FD4ED8A-B65E-4A3F-90FB-F5B5D230D731.

Evidence of post-polymerization of 110-million-year-old Spanish amber and its consequences for rejuvenation-based interpretation

Heating erases the history of a physically aged glass and cooling thereafter produces the original, unaged glass, i.e., a low-enthalpy glass is said to be rejuvenated by one heat-cool cycle. The knowledge is used in interpreting some properties of millions-year-old fossil amber [Nat. Commun. 4 (2013) 1783; J. Phys.: Condens. Matter, 25 (2013) 295402; Phys. Rev. Lett. 112 (2014) 165901], a naturally-occurring organic glass produced by free radical polymerization and a multiplicity of chemical reactions in the exuded resin of certain trees. Here we analyze the available heat capacity data of 110-million-year-old Spanish fossil amber that was used as a model for investigating the aging effect on physical properties of a glass and show that it post-polymerizes on heating its melt state. This causes the crosslinked structure of the melt-cooled amber to slightly differ from that of fossil amber and therefore there is no rejuvenation. Discussion of the aging effect and Boson peak height in terms of potential energy landscape need reconsideration, especially when the unaged state of amber is not available for comparison.

MicroCT data provide evidence correcting the previous misidentification of an Eocene amber beetle (Coleoptera, Cicindelidae) as an extant species

The fossil record suggests some insect species have a marked longevity. The oldest fossils purported to represent extant insect species are from the Oligocene and Eocene. One of the most cited fossils is the extant tiger beetle Tetracha carolina (Coleoptera: Cicindelidae) that was identified over a century ago by Walther Horn in Eocene Baltic amber. We examined this and compared it to the previously described cincindelid Baltic amber fossil Palaeoiresina cassolai using X-ray microscopy and 3D imaging techniques. We conclude that Horn’s fossil tiger beetle specimen is conspecific with the Eocene P. cassolai and is a member of an extinct stem group lineage of Cicindelidae. Based on a review of all the tiger beetle fossils described from Cretaceous and Paleogene deposits, we found that the assignment of these fossil species to extant lineages is not supported. There are currently no synapomorphies known from fossils that can provide evidence for Cretaceous Manticorni or Megacephalini nor is there evidence for Eocene Iresina. We provide evidence that rejects the idea of a recent beetle species persisting since the Eocene period, which is crucial for using the currently known fossil Cicindelidae species to calibrate divergence dating of beetle phylogenies.

A new compression fossil, Eotriadomeroides abjunctus Huber, gen. & sp. nov. (Hymenoptera, Mymaridae), in Eocene shale from the Kishenehn Formation, USA

A new fossil genus and species of fairyfly, Eotriadomeroides abjunctus Huber & Greenwalt, gen. and sp. nov. (Hymenoptera: Chalcidoidea: Mymaridae), is described and illustrated from a female preserved as a compression fossil in middle Eocene shale from the Kishenehn Formation, Montana, USA. It is compared to extant species of Neotriadomerus Huber, known only from Australia, and Triadomerus Yoshimoto, a Cretaceous amber fossil from Canada. It is suggested that these three genera, classified together in Triadomerini, likely the most ancestral lineage of Mymaridae, are evidence of the Middle or perhaps Late Jurassic origin of the family.

Threads of memory: Reviving the ornament of a dead child at the Neolithic village of Ba`ja (Jordan).

In 2018, a well-constructed cist-type grave was discovered at Ba`ja, a Neolithic village (7,400-6,800 BCE) in Southern Jordan. Underneath multiple grave layers, an 8-year-old child was buried in a fetal position. Over 2,500 beads were found on the chest and neck, along with a double perforated stone pendant and a delicately engraved mother-of-pearl ring discovered among the concentration of beads. The first was found behind the neck, and the second on the chest. The meticulous documentation of the bead distribution indicated that the assemblage was a composite ornament that had gradually collapsed, partly due to the burying position. Our aim was to challenge time degradation and to reimagine the initial composition in order to best explore the significance of this symbolic category of material culture, not as mere group of beads, but as an ornamental creation with further aesthetic, artisanal and socioeconomic implications. The reconstruction results exceeded our expectations as it revealed an imposing multi-row necklace of complex structure and attractive design. Through multiple lines of evidence, we suggest that the necklace was created at Ba`ja, although significant parts of beads were made from exotic shells and stones, including fossil amber, an unprecedented material never attested before for this period. The retrieval of such an ornament from life and its attribution to a young dead child highlights the significant social status of this individual. Beyond the symbolic functions related to identity, the necklace is believed to have played a key role in performing the inhumation rituals, understood as a public event gathering families, relatives, and people from other villages. In this sense, the necklace is not seen as belonging completely to the realm of death but rather to the world of the living, materializing a collective memory and shared moments of emotions and social cohesion.

Leptoomidae, a new family of Eocene fossil Chalcidoidea (Hymenoptera), and family classification of Eocene fossil genera originally described in Neanastatinae (Eupelmidae).

Leptoomidae Gibson fam. nov. (Chalcidoidea) is described for the Eocene Baltic amber fossil genera Leptoomus Gibson, type genus, reassigned from Tanaostigmatidae, and Neanaperiallus Gibson, reassigned from Neanastatinae (Chalcidoidea: Eupelmidae) sensu Gibson (2009). One new species of Neanaperiallus, N. defunctus Fusu sp. nov., is described. The new family is differentiated from other families of Chalcidoidea that are partly characterized by a greatly enlarged acropleuron. In species of Leptoomidae the prepectus is anteriorly rounded to angulate and extends to or slightly over the posterolateral margin of the pronotum, with the dorsal prepectal margin intersecting the base of the tegula distinctly anterior to and forming an almost right-angle with the posterior margin of prepectus, and the posterior margin truncate along the anterior margin of the acropleuron. This prepectal structure is similar to that in Tanaostigmatidae and Cynipencyrtidae, except the prepectus is elongated anteriorly exterior to the pronotum in Tanaostigmatidae and interior to the lateral surface of the pronotum in Cynipencyrtidae. A difference in prepectal structure also indicates that an anteriorly elongated mesoscutal process internal to the pronotum in Encyrtidae is convergent to that of Cynipencyrtidae, and similarity in shape of the prepectus among Encyrtidae, Eopelma Gibson and Neanastatus Girault might be functionally correlated with an anterior elongation of the mesoscutal process. New or corrected morphological data are provided for the two included genera. Of other Eocene fossil genera originally classified in Neanastatinae, Brevivulva Gibson and Propelma Trjapitzin, are assigned to Neanastatidae sensu Burks et al. (2022) based on similar mesoscutellar structures. Possible relationships of Aspidopleura Gibson, a taxon with a puzzling combination of features, are discussed. Because Aspidopleura cannot be placed with confidence in any extinct or extant higher taxon it is treated as incertae sedis at family level within Chalcidoidea.

X-ray micro-computed tomography of minute hooded beetles (Coleoptera: Corylophidae) reveals its hidden paleodiversity in the Eocene Baltic amber

Fossil Corylophidae are poorly known. Three fossil representatives of the family were described until now: one from mid-Cretaceous (Mesozoic) and two from Eocene (Cenozoic) deposits. We revise corylophid material from Baltic amber using X-ray micro-computed tomography (μCT) and describe two new species: Clypastraea venedorum n. sp. and C. groehni n. sp. The systematic placement of the previously described Baltic amber fossil Clypastraea primainterparesAlekseev, 2016 was confirmed. The re-description and diagnosis will help the systematic study on the extant and extinct species of the family. Micro-CT was used for the first time to study a members of Corylophidae. An identification key for Eocene representatives of the genus Clypastraea is provided. The species-rich palaeofauna of this group of corylophid beetles (the most diverse fossil record to date) is briefly discussed in the context of diverse plant communities of Eocene amber forest.

Evolutionary assessment of the rove beetle subfamily Proteininae Erichson, 1839 (Coleoptera: Staphylinidae) triggered by the X-ray based description of its first fossil in Baltic amber from Denmark

ABSTRACT The taxonomic composition, phylogeny, ecology, biology, behaviour, and fossil record of Proteininae Erichson, 1839 is reviewed to place the first Eocene fossil specimen from Baltic amber in the knowledge framework of this rove beetle subfamily. The Baltic amber fossil is a poorly preserved female which was examined using X-ray micro-computed tomography (μ-CT). It is assigned to the genus Proteinus Latreille, which is represented by 53 extant species in the world fauna, most of which occur in the north temperate areas of the globe. Due to a shortage of data, this newly discovered fossil could not be identified to the species level. However, it is the first known fossil of Proteinus, which indicates that the genus has been present since at least the Late Eocene. Together with other fossils, and what is so far known about the phylogeny of Proteininae and allied groups, it suggests that while the subfamily Proteininae dates back at least to the mid-Cretaceous, its species-rich lineages may be significantly younger. Open questions about the evolution of Proteininae, including reasons for the mainly bipolar geographical distribution of its extant members or the imbalanced diversity with recent Proteinus and Megarthrus from Proteinini being the only species-rich taxa with a global distribution, are discussed. Proteinus sp. from Baltic amber is a valuable piece of evidence for future research in this direction.

Pastillus aethiopicus n. sp. (Coleoptera: Cybocephalidae), a new fossil beetle from Miocene Ethiopian amber and a taxonomic key to the species of Pastillus Endrödy-Younga

We describe a new species of Cybocephalidae (Coleoptera) from Ethiopian Miocene amber, Pastillus aethiopicus n. sp. This is the second beetle species discovered in that fossiliferous amber deposit. It is the fourth species described in the extant genus Pastillus Endrödy-Younga and the first fossil species discovered. Pastillus is reviewed, the species diagnosed, listed, keyed, and distribution data recorded. Additionally, checklists of fossil Cybocephalidae, and African Cybocephalidae fauna are provided.