Chemical preservation of plants and insects in natural resins

The morphological preservation of fossils in amber is remarkable, but their chemical composition is largely unknown. The likelihood of DNA preservation in amber has been questioned but, surprisingly, the fate of more decay-resistant macromolecules such as ligno-cellulose in plants or the chitin–protein complex in insect cuticle has not been investigated. Here we report the results of investigations using pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) of the tissues of insects and the plant Hymenaea from ancient and sub-fossil resins (2–20 ka) from Kenya, and from Dominican amber (25–30 Ma). The volatile components of the resin have penetrated even the internal tissues, resulting in the exceptional three-dimensional preservation of amber inclusions. Chitin is preserved in the bee and ligno-cellulose in the Hymenaea leaf from the Kenyan resins. There was no trace, however, of these macromolecules in tissues in Dominican amber. The presence of aliphatic polymer and sulphur-containing moieties in these tissues indicates that they have undergone diagenetic alteration; in view of this, the preservation in Dominican amber of a macromolecule as labile as DNA would be extraordinary.     

How long can insect species exist? Evidence from extant and fossil Micromalthus beetles (Insecta: Coleoptera)

Six new fossils of Micromalthus (Coleoptera: Archostemata) from Dominican amber are compared with extant and previously described fossil micromalthid beetles. The amber inclusions are well preserved and all important morphological features are visible. Taking into account the morphological variability of the extant species Micromalthus debilis LeConte, 1878 , it is not possible to find any morphological features that distinguish the fossils from the extant species. This also applies to the Dominican amber inclusion described as Micromalthus anasi Perkovsky, 2008, which therefore is considered a junior synonym of M. debilis. The lack of morphological change in M. debilis over time might possibly be explained by unusually stable environmental conditions, as this species occupies a very specialized ecological niche in decaying timber. A general survey of fossil insects indistinguishable from extant species is presented. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 300–311.     

Fossil palm flowers in Dominican and Baltic amber

Five palm flowers in Dominican amber and one in Baltic amber are described or characterized. Palaeoraphe dominicana gen. et sp. nov. in the subtribe Livistoninae, is described from one perfect flower in Dominican amber. Roystonea palaea sp. nov. is described from one staminate and one pistillate flower in Dominican amber. Three other palm flowers, two perfect flowers from Dominican amber and one staminate flower from Baltic amber, are briefly characterized and figured.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 361–367.     

Insect outbreaks produce distinctive carbon isotope signatures in defensive resins and fossiliferous ambers

Despite centuries of research addressing amber and its various inclusions, relatively little is known about the specific events having stimulated the production of geologically relevant volumes of plant resin, ultimately yielding amber deposits. Although numerous hypotheses have invoked the role of insects, to date these have proven difficult to test. Here, we use the current mountain pine beetle outbreak in western Canada as an analogy for the effects of infestation on the stable isotopic composition of carbon in resins. We show that infestation results in a rapid (approx. 1 year) (13)C enrichment of fresh lodgepole pine resins, in a pattern directly comparable with that observed in resins collected from uninfested trees subjected to water stress. Furthermore, resin isotopic values are shown to track both the progression of infestation and instances of recovery. These findings can be extended to fossil resins, including Miocene amber from the Dominican Republic and Late Cretaceous New Jersey amber, revealing similar carbon-isotopic patterns between visually clean ambers and those associated with the attack of wood-boring insects. Plant exudate δ(13)C values constitute a sensitive monitor of ecological stress in both modern and ancient forest ecosystems, and provide considerable insight concerning the genesis of amber in the geological record.     

Ancient Ephemeroptera–Collembola Symbiosis Fossilized in Amber Predicts Contemporary Phoretic Associations

X-ray computed tomography is used to identify a unique example of fossilized phoresy in 16 million-year-old Miocene Dominican amber involving a springtail being transported by a mayfly. It represents the first evidence (fossil or extant) of phoresy in adult Ephemeroptera and only the second record in Collembola (the first is also preserved in amber). This is the first record of Collembola using winged insects for dispersal. This fossil predicts the occurrence of similar behaviour in living springtails and helps explain the global distribution of Collembola today.     

Paleorhodococcus dominicanus n. gen., n sp. (Actinobacteria) in a faecal droplet of Triatoma dominicana (Hemiptera: Reduviidae: Triatominae) in Dominican amber

Paleorhodococcus dominicanus n. gen., n sp. (Actinobacteria) is described from a faecal droplet of Triatoma dominicana (Hemiptera: Reduviidae: Triatominae) in Dominican amber. The fossil can be distinguished from the species of the closely related extant genus Rhodococcus Zopf 1891 by its spherical–ellipsoidal cocci forming substrate filaments with elementary branching, the clustering of coccoidal elements, the short filaments bearing reduced side branches and its occurrence in a faecal droplet of the extinct triatomine bug, P. dominicanus. This is the first fossil record of an Actinobacter, which shows that these organisms formed symbiotic associations with insects by the mid-Tertiary.     

First fossil horsefly (Diptera: Tabanidae) in Miocene Mexican amber

The fossil record of the Tabanidae is sparse when compared with other families of Diptera. Even in amber they are rare, probably because of their size and specific flight behavior. Horseflies from amber are only known from Cretaceous age New Jersey amber as well as from the Tertiary age Baltic and Dominican amber, but are herein described for the first time, with Stenotabanus oleariorum sp. n., from Mexican amber. The new species is compared to the fossil horseflies of the same genus S. brodzinskyi Lane, Poinar and Fairchild 1988 and S. woodruffi Lane and Fairchild 1989 from Dominican amber.     

Ecology and taphonomy of Dominican Republic amber and its inclusions

The taphonomic influences upon fossil faunas are generally assumed to be substantial, but in amber they have been little investigated. By comparing the inclusions in Tertiary amber from the Dominican Republic (Smithsonian Institution's Brodzinsky-Lopez Peña collection) with modern insect populations sampled using various methods and from different habitats, it is possible to test taphonomic hypotheses that bear on interpretations of amber faunas. The biota trapped in amber is here viewed as analogous to modem faunas sampled with man-made traps. Using cluster analysis (Manhattan and Euclidian distance measures -UPGMA clustering algorithm) to compare faunas, the amber-trap fauna is most closely reproduced by present day collection using emergence traps and also shows a strong similarity to the fauna of pitfall trap samples. Faunal dissimilarities indicate that the utility of Dominican Republic amber fossils is limited for ecological studies of the canopy and shrub layers of forests, or of the Orders Coleoptera, Diptera or Hymenoptera. Similarities between modern faunas and the amber fauna allow predictions about the ecological setting of Tertiary amber production: this is indicated as primary rain forest, with regenerating patches of secondary growth, in a low-altitude riparian location. □ Amber, Dominican Republic, Palaeogene, ecology, taphonomy.     

Fossil evidence of insect pathogens

The present report describes fossil evidence of insect pathogens, heretofore, almost non-existent, from six samples of amber ranging in age from 15 to 100 million years. They include a cytoplasmic polyhedrosis virus and trypanosomatid infection in an adult biting midge (Diptera: Ceratopogonidae), and a nuclear polyhedrosis virus in an adult sand fly (Diptera: Phlebotomidae), both from Early Cretaceous Burmese amber, several types of fungal thalli on the cuticle of an adult mosquito (Culicidae: Diptera), as well as a fungal growth on the prothorax of a fungus gnat (Mycetophilidae: Diptera) in Dominican amber and large tumors in the body cavity of a caterpillar (Lepidoptera) in Mexican amber. These discoveries suggest that insect polyhedrosis viruses were present 100 million years ago and present the possibility that vertebrate arboviruses (especially those in the family Reoviridae) could have evolved from cytoplasmic polyhedrosis viruses infecting biting insects. The flagellates in the Early Cretaceous biting midge represent the first fossil record of monogenetic trypanosomatid infections of arthropods.     

A fungal-like organism associated with a wasp (Hymenoptera: Pteromalidae) in Dominican amber

A fungal-like organism emerging from a parasitic wasp (Hymenoptera: Pteromalidae) in Dominican amber is characterized. The fossil consists of a white sclerotium-like formation in the wasp's abdomen and a flattened clava-like structure with an ovoid terminus emerging from the sclerotium-like formation. The ovoid terminus bears a protruding elliptical appendix. The fossil, which is characterized by its small size, somatic configuration, pteromalid host and presence in Dominican amber, cannot be placed with assurance in any extant fungal group at this time.     

A fossil scorpion Tityus geratus new species (Scorpiones: Buthidae) from Dominican Amber

A fossil scorpion, Tityus geratus (Scorpioncs: Buthidae) n. sp., is described from Dominican amber. This is the third described amber Tityus sp. and the third Dominican amber scorpion. On the basis of the amber finds and available knowledge on the present distribution of Tityus spp. in the Antilles, the vicariance model of Caribbean biogeography can be evoked to best explain the present distribution of this genus.     

Another fossil agaric from Dominican amber

We report the discovery of a fossil agaricoid homobasidiomycete from Dominican amber (ca 15-20 Ma). Aureofungus yaniguaensis appears to be a member of the euagarics clade, but its precise taxonomic placement is obscure. This is the fourth known fossil agaric and the third from Dominican amber.     

Evidence of parasitism by Strepsiptera in Dominican amber

Fossil evidence of parasitism byStrepsiptera is presented by the discovery of amale pupa in a halictid bee (Halictidae:Hymenoptera) and female and male pupae inrepresentatives of two families of planthoppers(Delphacidae and Achilidae: Fulgoroidea) in 15–45 million year old Dominican amber. In thecase of the delphacid, the first stagestrepsipteran larvae were making their exitfrom the brood chamber at the time of capture.The fossils are compared with extantinsect-strepsiptera associations inMesoamerica. These rare finds, which includethe first fossil record of strepsipteran larvaeassociated with a host insect, establish aminimum age for parasitism of halictid bees andplanthoppers by strepsipterans.     

New Tridactyloidea in Miocene amber from the Dominican Republic (Orthoptera: Caelifera)

Two new Tridactyloidea of the families Ripipterygidae and Tridactylidae are described from the Early Miocene (Burdigalian) amber of the Dominican Republic, namely: Archaeoellipes engeli n. gen., n. sp. (Tridactylidae: Tridactylinae) and Mirhipipteryx antillarum n. sp. (Ripipterygidae). These new taxa represent the fi rst record of Tridactyloidea in Dominican amber and the fi rst fossil record of Ripipterygidae, which are otherwise known only from the extant fauna.     

13C NMR and IR analyses of structure,aging and botanical origin of Dominican and Mexican ambers

¹³C NMR analysis of Oligocene amber from the Dominican Republic, Oligo-Miocene amber from Mexico and trunk resins from certain extant species of Hymenaea, suggests a polylabdane structure for all and gives insights into structural changes during aging. Additionally, IR spectra, some aspects of the ¹³C NMR spectra and paleobotanical data suggest a close relationship between Dominican amber and H. verrucosa. By contrast, spectral evidence shows that Mexican amber differs, not only from the former polymers, but from the H. courbaril polymer.     

Fossil palm flowers in Dominican and Mexican amber

Twelve palm flowers in one piece of Dominican amber and a single flower in a second piece are described as Trithrinax dominicana sp. nov. (Thrinacinae: Coryphoideae), representing the first fossil record of this genus. There are no members of Trithrinax in the Greater Antilles today. Two staminate flowers in Mexican amber are described as Socratea brownii sp. nov. (Iriarteinae: Arecoideae) and represent the first fossils of this genus. A third palm flower in Mexican amber, possibly belonging to the subtribe Euterpeinae, is characterized. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 138 , 57–61.     

Paleotrichius dominicanus n. gen., n. sp. (Coleoptera; Cetoniidae), a flower beetle in Dominican amber

A new genus and species of flower beetle, Paleotrichius dominicanus, n. gen., n. sp. (Coleoptera: Cetoniidae: Trichinae) is described from Dominican amber. The new taxon is distinguished from all other New World trichines by the combination of the shape of the clypeus, pronotum, protibia, the femoral and tibial armature, the mesosternal process separating the middle coxae, the distinct strial pattern on the elytra and the approximate claws. The beetle may have been quite colourful and a strong flyer attracted to flowers. The larvae most likely developed in decaying hardwoods in the Dominican amber forest. This is the first amber representative of the family Cetoniidae.     

The first fossil Paussine (Coleoptera: Carabidae) from Mexican amber

Eohomopterus simojovelensis n. sp., the first fossil record of the subfamily Paussinae (Coleoptera: Carabidae) from the Miocene amber of the Simojovel area, Chiapas, Mexico, is described. The morphology of the new species is compared withEohomopterus poinari Nagel, 1997 from Dominican amber as well as with extant representatives ofEohomopterus, and the biogeographical implications are discussed.      

New fossil paussids from Dominican amber with notes on the phylogenetic systematics of the paussine complex (Coleoptera: Carabidae)

The first fossil representative of the Protopaussinae and the second fossil Eohomopterus (Paussinae) are described from amber inclusions of Tertiary age collected in the Dominican Republic on the West Indian island of Hispaniola ( Protopaussus pristinus sp.n., Eohomopterus poinari sp.n.). These finds increase the total number of paussids present in Dominican amber to four species in three genera ( Protopaussus , Eohomopterus , Homopterus ). A key is provided for the identification of the New World genera of Protopaussinae and Paussinae and for the species of Eohomopterus . Based on synapomorphic character states, the paussid beetles are split into two subfamilies, the monobasic Protopaussinae and the more inclusive Paussinae (the twenty-three genera are placed into two supertribes: the Carabidomemnitae comprising two tribes and the Paussitae comprising eight tribes. The extant congeners of Eohomopterus and Homopterus live in the Neotropical Region, while the extant members of Protopaussus are known only from the Oriental Region. This record of New World Tertiary Protopaussus adds another example of the Old World relationships of taxa from Dominican amber. The temporal and geographical distribution of Protopaussus indicates that its present zoogeographical range may represent the relict of a wide Laurasian distribution in the past. It does not support the previously suspected Oriental centre of origin for the ancestral stock of {Protopaussinae + Paussinae}.