Amber Research Articles

Lichen preservation in amber: morphology, ultrastructure, chemofossils, and taphonomic alteration

Abstract. The fossil record of lichens is scarce and many putative fossil lichens do not show an actual physiological relationship between mycobionts and photobionts or a typical habit, and are therefore disputed. Amber has preserved a huge variety of organisms in microscopic fidelity, and so the study of amber fossils is promising for elucidating the fossil history of lichens. However, so far it has not been tested as to how amber inclusions of lichens are preserved regarding their internal characters, ultrastructure, and chemofossils. Here, we apply light microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Raman spectroscopy to an amber-preserved Eocene lichen in order to gain information about the preservation of the fossil. The lichen thallus displays lifelike tissue preservation including the upper and lower cortex, medulla, photobiont layer, apothecia, and soredia. SEM analysis revealed globular photobiont cells in contact with the fungal hyphae, as well as impressions of possible former crystals of lichen compounds. EDX analysis permitted the differentiation between halite and pyrite crystals inside the lichen which were likely formed during the later diagenesis of the amber piece. Raman spectroscopy revealed the preservation of organic compounds and a difference between the composition of the cortex and the medulla of the fossil.

Transfer of the EoceneJungermannia berendtiiGrolle toSolenostoma

Abstract The Baltic amber fossil Jungermannia berendtii is transferred to Solenostoma based on the presence of numerous long rhizoids, distinct trigones, and subquadrate-rotund to elongate-elliptical leaves.

Histiostoma ovalis (Histiostomatidae, Acari) associated with Ips sexdentatus (Scolytinae, Curculionidae, Coleoptera): ecology and mite redescription on the basis of formerly unknown adults and nymphs

Histiostomatidae represent a clade within the Astigmata and disperse phoretically by the highly modified deutonymph. A monophyletic species group within the Histiostomatidae, the bark-beetle-clade, includes mites associated with bark beetles (Scolytinae). Histiostoma ovalis Müller, 1860, only known by the morphology of its deutonymph, is a member of this clade. Since almost 150 years other developmental stages of the mite were never described. Thus we hereby present adults and nymphal instars of H. ovalis for the first time and designate a neotype. Mites were reared starting from phoretic deutonymphs, collected from adults of Ips sexdentatus and from its original galleries, found in Southern Italy and Germany. Additional deutonymphs were examined from the Slovak Republic and Croatia. During the last 60 years there has been confusion about the identity of two species, Histiostoma ovalis Müller, 1860 and H. gladiger Vitzthum, 1926, which were assumed by some authors to be synonymous. We do not contribute new findings about H. gladiger, but in this paper we define the mite, which is usually associated with Ips sexdentatus, as H. ovalis. Almost 100% of adult beetle individuals collected from their galleries in the bark of pine trees were covered with deutonymphs. The average number of deutonymphs per beetle and information of the preferred areas for mite-attachment on the beetle body are presented. Fungal spores were discovered sticking to the cuticle of deutonymphs and other mite instars. Hyperphoresy with deutonymphs of H. ovalis, riding on gamasid mites, which represent also phoretic passengers of I. sexdentatus, was additionally observed.For a better description of H. ovalis, mite specimens from Germany were used to achieve DNA barcoding-sequences. A Baltic amber fossil of an extinct bark beetle, which has four phoretic histiostomatid mite deutonymphs attached to its body, is presented. There is morphological evidence that those deutonymphs could be phylogenetically closely related to H. ovalis.

New Genera and Species of Plokiophilidae from Australia, Fiji, and Southeast Asia, with a Revised Classification of the Family (Insecta: Heteroptera: Cimicoidea)

ABSTRACT Monteithophila queenslandana, new genus and new species, is described from Queensland, Australia, and represents the first record of the family Plokiophilidae from the continent. Morphology of the male genitalia is similar to that found in Heissophila Schuh from Thailand and therefore the traumatic insemination as found in other members of the family is hypothesized to be absent in Monteithophila. The female of an apparently congeneric taxon from Fiji is described as Monteithophila fijiensis. Paraplokiophiloides schwendingeri, new genus and new species, is described from Thailand. Female genitalic morphology in the Plokiophilidae is documented with laser confocal microscopy. A revised classification of the Plokiophilidae is proposed in order to establish congruence between observed morphological characters and the recognized higher-taxonomic groupings. The new subfamily Heissophilinae is erected to include Heissophila, Moneithophila, and the Baltic amber fossil Pavlostysia Popov. The concept of P...

A new Dominican amber fossil of the derived fern genus Pleopeltis confirms generic stasis in the epiphytic fern diversity of the West Indies

One of the grand objectives in the integration of fossils and phylogenetics is to obtain support for macroecological and macroevolutionary hypotheses. Here, we provide new evidence from Dominican amber fossils, which supports a likely stasis in the generic composition of epiphytic plant communities in the West Indies for at least 16 million years. The proposed hypothesis is based on the discovery of the first fossil of the Neotropical fern genus Pleopeltis. The relationships of this specimen to extant genera are studied using a dated phylogenetic framework to reconstruct the evolution of the characters preserved in the fossil, as well as by exploring the phylomorphospace of Pleopeltis. The fossil corroborates divergence time estimates obtained independently and also suggests the conservation of the generic composition of epiphytic communities. We discovered evidence for conserved morphotypes in the genus Pleopeltis occurring from the mid-Miocene to the present. The innovative use of phylomorphospace reconstruction provided crucial information about the affinities of the fossil. Rather than relying on reconstructing the evolution of single characters, this analysis integrates the evolution of all informative characters observed to evaluate relationships of the fossilized morphotype to extant morphotypes.

Eocene and not Cretaceous origin of spider wasps (Pompilidae): fossil evidence from amber

Spider wasps had long been proposed to originate in the Late Cretaceous based on the Burmese amber fossil Bryopompilus interfector. We performed a morphological examination of this fossil and determined that it does not belong to Pompilidae or any other described hymenopteran family. Instead, we place it in the new family Bryopompilidae. The oldest verifiable member of the Pompilidae is from Baltic amber, which suggests that the crown group of the family probably originated in the Eocene, not in the Late Cretaceous as previously proposed. The origin of spider wasps appears to be correlated with an increase in spider familial diversity in the Cenozoic. We also add two genera to the extinct pompilid fauna: Tainopompilus Rodriguez and Pitts gen. nov. and Paleogenia Waichert and Pitts gen. nov., and describe three new species of fossil spider wasps: Anoplius planeta Rodriguez and Pitts sp. nov., from Dominican amber (Burdigalian to Langhian); Paleogenia wahisi Waichert and Pitts sp. nov., from Baltic amber (L...

Introduction to thematic volume “Fossil arthropods in Late Cretaceous Vendean amber (northwestern France)”

There is growing knowledge of the insect and arachnid Cretaceous diversity worldwide, most notably as a result of the discovery, in the past twenty years, of numerous Konservat-Lagerstatten (highly fossiliferous deposits) that provide a plethora of fossil arthropods (Wang & Szwedo, 2014). Early Cretaceous (Berriasian–Aptian) insects are known primarily from imprints in rocks, while fossiliferous amber yielding arthropod inclusions range mostly from the Albian to the Campanian – the sole exception being Hauterivian-Barremian amber of Lebanon and Jordan.

Amber

The amber fossil record provides a distinctive, 320-million-year-old taphonomic mode documenting gymnosperm, and later, angiosperm, resin-producing taxa. Resins and their subfossil (copal) and fossilized (amber) equivalents are categorized into five classes of terpenoid, phenols, and other compounds, attributed to extant family-level taxa. Copious resin accumulations commencing during the early Cretaceous are explained by two hypotheses: 1) abundant resin production as a byproduct of plant secondary metabolism, and 2) induced and constitutive host defenses for warding off insect pest and pathogen attack through profuse resin production. Forestry research and fossil wood-boring damage support a causal relationship between resin production and pest attack. Five stages characterize taphonomic conversion of resin to amber: 1) Resin flows initially caused by biotic or abiotic plant-host trauma, then resin flowage results from sap pressure, resin viscosity, solar radiation, and fluctuating temperature; 2) entrapment of live and dead organisms, resulting in 3) entombment of organisms; then 4) movement of resin clumps to 5) a deposition site. This fivefold diagenetic process of amberization results in resin→copal→amber transformation from internal biological and chemical processes and external geological forces. Four phases characterize the amber record: a late Paleozoic Phase 1 begins resin production by cordaites and medullosans. A pre-mid-Cretaceous Mesozoic Phase 2 provides increased but still sparse accumulations of gymnosperm amber. Phase 3 begins in the mid-early Cretaceous with prolific amber accumulation likely caused by biotic effects of an associated fauna of sawflies, beetles, and pathogens. Resiniferous angiosperms emerge sporadically during the late Cretaceous, but promote Phase 4 through their Cenozoic expansion. Throughout Phases 3 and 4, the amber record of trophic interactions involves parasites, parasitoids, and perhaps transmission of diseases, such as malaria. Other recorded interactions are herbivory, predation, pollination, phoresy, and mimicry. In addition to litter, amber also captures microhabitats of wood and bark, large sporocarps, dung, carrion, phytotelmata, and resin substrates. These microhabitats are differentially represented; the primary taphonomic bias is size, and then the sedentary vs. wandering life habits of organisms. Organismic abundance from lekking, ant-refuse heaps, and pest outbreaks additionally contribute to bias. Various techniques are used to image and analyze amber, allowing assessment of: 1) ancient proteins; 2) phylogenetic reconstruction; 3) macroevolutionary patterns; and 4) paleobiogeographic distributions. Three major benefits result from study of amber fossil material, in contrast to three different benefits of compression-impression fossils.

Extension of historical range of Betylobraconinae (Hymenoptera: Braconidae) into Palaearctic Region based on a Baltic amber fossil, and description of a new species of Mesocentrus Szépligeti from Papua New Guinea.

Two new species of the parasitic wasp genus Mesocentrus Szépligeti (Betylobraconinae) are described. One based on a new species from Papua New Guinea, the other the first Palaearctic member of the subfamily based on a 30+ mya, species from Baltic amber. The second species is illustrated using synchrotron X-ray microtomography. Whereas the extant Betylobraconinae are restricted to Australia, New Guinea and New Caledonia, their ancestral distribution is now known to have extended considerably further. A key to the four species of Mesocentrus known from Papua New Guinea is provided. Both species possess some putatively plesiomorphic characters absent in other extant Mesocentrus spp. The new extant species differs in having a considerably larger number of antennal segments and a less laterally depressed frons, while the extinct one has the clypeus separated from the face dorsally and strongly developed hypoclypeal depression. Availability of sequence data for this species enabled further analysis of the relationships of the subfamily, which we present in a phylogenetic analysis additionally including the release of a number of new sequences of related taxa.

The Fire Wish by Amber Lough (review)

The Fire Wish by Amber Lough (review)

A rare diving beetle from Baltic amber:Hydrotrupes prometheusnew species reveals former widespread distribution of the genus (Coleoptera, Dytiscidae)

A new species in the extant genus,HydrotrupesSharp,H. prometheusn. sp., (Coleoptera, Dytiscidae) is described from Baltic amber (Eocene) based on examination of a single female specimen. This description represents one of a limited number of diving beetle taxa described from fossiliferous amber and is currently the oldest known fossil assigned to Agabinae. Based on this specimenHydrotrupesis at least 40 million years old. The occurrence ofHydrotrupesduring the Eocene suggests that the current disjunct distribution of livingHydrotrupesspecies occurring in western North America and eastern China is a relict of former widespread distribution in the northern continents. Considering the age of this fossil and its similarity to living members of the genusHydrotrupes, the conservation of morphology in this lineage of diving beetles is notable. Key morphological characters of the new species are illustrated, and the significance of this discovery for understanding Agabinae evolution and the biogeography of this previously hypothesized trans-Beringian lineage is discussed.

Baltorussus total makeover: rejuvenation and sex change in an ancient parasitoid wasp lineage.

The Orussidae is a small and rare but phylogenetically important family of parasitoid wasps. The fossil record of the family is also very poor. Baltorussus velteni was described from Baltic amber from an allegedly female specimen. This and another recently discovered specimen are examined with microCT scanning and standard microscopy. We reveal that both the holotype and the new specimen are actually males. Furthermore, the results of the microCT scanning allow us to integrate the fossils in a morphological data set assembled for extant Orussidae. Phylogenetic analyses consistently retrieve Baltorussus as a separate basal lineage within the crown group, whereas two Cretaceous fossils are placed as stem group orussids and a Dominican amber fossil in an extant genus. Based on the positions of the fossils, we estimate that the extant Orussidae radiated in the mid-Cretaceous (approx. 100 Ma ago). This is considerably younger than a previously suggested Early Jurassic date (180 Ma ago), which was primarily based on biogeographic evidence.

Robber Flies in Cretaceous Ambers (Insecta: Diptera: Asilidae)

ABSTRACT Cretaceous fossils of Asilidae are reviewed, and two new taxa from Burmese and Raritan (New Jersey) ambers are described. The first robber fly from Burmese amber, †Burmapogon bruckschi, new genus and species, is described based on specimens of both sexes. A scientific name is provided for the previously described but unnamed fossil assassin fly from Raritan amber, †Cretagaster raritanensis, new genus and species, preserved as a fragmentary specimen. The amber fossils are placed phylogenetically within Asilidae. Specifically, †Burmapogon is postulated to be a representative of the clade comprised of (Brachyrhopalinae + Stichopogoninae), while †Cretagaster is a member of the Leptogastrinae and postulated to be an extinct sister group to (Acronychini + Leptogastrini).

Pieces of Me by Amber Kizer (review)

Pieces of Me by Amber Kizer (review)

Reassessment of Paleotachina Townsend and Electrotachina Townsend and their removal from the Tachinidae (Diptera)

The monotypic genera Paleotachina Townsend, 1921 and Electrotachina Townsend, 1938 were originally described as fossils in amber but were later discovered to be inclusions in copal. Both taxa were originally assigned to the Tachinidae (Diptera) and this placement has continued to the present day. The holotypes of the two type species, P. smithii Townsend and E. smithii Townsend, were examined and the following taxonomic and nomenclatural changes are proposed: Paleotachina is transferred to the Muscidae and placed in synonymy with Aethiopomyia Malloch, 1921, syn. n.; P. smithii Townsend, type species of Paleotachina, is synonymized with Aethiopomyia gigas (Stein, 1906), syn. n.; Electrotachina is transferred to the Sarcophagidae and placed in synonymy with Dolichotachina Villeneuve, 1913, syn. n.; E. smithii Townsend, type species of Electrotachina, is recognized as a valid species of Dolichotachina comb. n. Images of the holotypes of P. smithii and E. smithii are provided and features that have helped place these copal inclusions in their new combinations are discussed.

Ancient origins of the Mediterranean trap-door spiders of the family Ctenizidae (Araneae, Mygalomorphae)

The family Ctenizidae is a worldwide-distributed trapdoor spider group, with a modest number of genera and species but interesting biogeography. Its monophyly has been questioned on the basis of both morphological and molecular evidence. The family is represented in the Mediterranean Basin by three genera and nine species: Cteniza and Cyrtocarenum, mostly endemic to the region, and Ummidia, long considered an anthropogenic introduction to the Mediterranean because the bulk of its diversity is in the New World. The taxonomic status of some of the species and genera (e.g. Mediterranean Ummidia species or Cteniza and Cyrtocarenum) has been called into question due to their close morphological affinities. Here, we use a multilocus approach that combines DNA sequence data from three nuclear genes 28S rRNA, EF1γ and H3 to investigate the origins and phylogenetic position of the Mediterranean taxa within the context of ctenizid generic-level diversity. For the first time, all known ctenizid genera are included in a phylogenetic analysis. Additionally, Bayesian relaxed clock methods and specific substitution rates are used to infer the timing of the group’s diversification. Our results disagree with the traditional division of the family Ctenizidae into two subfamilies finding them polyphyletic and stress the need for re-evaluating the morphological characters that have been used in the group’s classification. Time estimates indicate an ancient origin and long history of Mediterranean ctenizids. The present day disjunct distribution of Ummidia seems to be the result of the opening of the Atlantic Ocean, suggesting a former Laurasian distribution of the genus that is further supported by Baltic amber fossils. Similarly, the opening of the western Mediterranean Basin has likely played a key role in the diversification of both Ummidia and Cteniza, whereas the origin of Cyrtocarenum species preceded the breakup of the former continuous landmass that formed the Aegean region. Deep divergence times and reciprocal monophyly support the status of Cteniza and Cyrtocarenum as independent evolutionary lineages. Alternatively, the taxonomic status of Ummidia with regard to the closely related genus Conothele remains unclear; a more thorough sampling of the latter is needed to evaluate whether the synonymy of the two genera is necessary.

Amber fossils of sooty moulds

Sooty moulds are saprophytic ascomycetes with brown hyphae, often forming extensive subicula on living plant surfaces. These fungi grow on plant exudates and honeydew secreted by sap sucking insects and are ubiquitous in many humid terrestrial ecosystems. Here, we review previously published specimens of sooty moulds and provide new fossil evidence that traces the fossil record of these fungi for about 100million years, from the early Miocene (17million years) to the Early Cretaceous (Albian, about 100 to 113million years). Investigation of Mesozoic and Cenozoic ambers from different parts of the world revealed sooty moulds from eight northern hemisphere amber deposits. Fragments of superficial subicula composed of smooth brown moniliform hyphae with tapering distal ends identical to those produced by extant species in the family Metacapnodiaceae (Capnodiales) are recorded since the Albian. The fossil fungi originate from tropical to temperate coastal forests where they grew on leaves and bark of different conifer and angiosperm trees. This indicates that capnodialean sooty moulds have occupied their specialized niche since at least from when early angiosperms appeared in the fossil record.

Using 20-million-year-old amber to test the super-Arrhenius behaviour of glass-forming systems

Fossil amber offers the opportunity to investigate the dynamics of glass-forming materials far below the nominal glass transition temperature. This is important in the context of classical theory, as well as some new theories that challenge the idea of an 'ideal' glass transition. Here we report results from calorimetric and stress relaxation experiments using a 20-million-year-old Dominican amber. By performing the stress relaxation experiments in a step-wise fashion, we measured the relaxation time at each temperature and, above the fictive temperature of this 20-million-year-old glass, this is an upper bound to the equilibrium relaxation time. The results deviate dramatically from the expectation of classical theory and are consistent with some modern ideas, in which the diverging timescale signature of complex fluids disappears below the glass transition temperature.

Myxomycete history and taxonomy: highlights from the past, present, and future

The past myxomycete legacy covers fruiting bodies preserved in fossil amber more than 35 million years ago and early contributions by Linnaeus, de Bary, and the Listers at the British Museum of Natural History (BM), among whom the Listers introduced monographs, striking watercolors, and more narrow species concepts. Macbride and Martin (University of Iowa) published illustrated myxomycete monographs with broader species concepts. The transfer of the ∼9500 specimen Iowa myxomycete collection to the United States National Fungus Collections (BPI) is outlined and ∼234 type specimens are listed. Also covered is Lado's recent Nomenmyx and the online resource nomen. eumycetozoa. com, which offers ∼900 names for accepted myxomycete species. The current status of the BM and BPI myxomycete collections is noted, and Didymium saturnus provides an example of data associated with myxomycete specimens in the American Type Culture Collection. Problematic taxa are recommended for DNA sequencing to help clarify phylogenetic relationships.

High resolution radiography of ambers with pixel detectors

Radiography serves as a powerful non-destructive technique for studying inner structure of biological samples and materials. In the last years X-ray imaging has taken advantage of the developments in instrumentation such as table-top micro-focus X-ray tubes and quantum counting pixel detectors. The imaging setups used for our measurements allow for the observation of tiny samples including fossils in amber. The main goal of the study was to apply microradiography as representative of non-destructive and non-invasive methods for imaging fossils in amber. Those fossils are generally not easy to visualize, especially their internal structures. We investigated a combination of sources and detectors: (a) an X-ray unit for mammography with tungsten anode, emissive spot of 100 μm and an amorphous selenium imager; (b) a micro-focus X-ray tube with tungsten anode, emissive spot of 5 μm and a flat panel imager; (c) a nano-focus X-ray tube with tungsten anode, with gauge of emissive spot of 1 μm and as imager the pixel semiconductor detector Medipix2. The study of fossils in amber can be for example not well visible because of the presence of organic detritus from various sources. The amber preserves various ancient biological objects which are fully or partly saturated with amber resin. These samples attenuate X-rays similarly, but the use of pixel detectors enables capturing these differences, without permanent destruction of the samples (cracking, slicing, etc.). Microradiographic studies are completed by the observation of amber fossils in scanning and transmission electron microscopes.