The first extinct species of Monolepta Chevrolat (Coleoptera: Chrysomelidae: Galerucinae) from Bitterfeld amber, described using X-ray micro-computed tomography

Based on a well preserved female specimen from Bitterfeld amber, Monolepta rappsilberi sp. nov. is described and illustrated using X-ray micro-computed tomography (μCT). It is the second reported member of Chrysomelidae from this fossil resin and the first described fossil Monolepta representative. The fossil species represents a lineage that is extinct in Recent Europe. A longitudinal carina on abdominal ventrite 5 of the female is a unique character for the subfamily Galerucinae.

Polymera alexanderi n. sp., a new species of Limoniidae (Diptera) from Dominican amber

Dominican amber is the fossil resin famous for the best quality of inclusions, exploited in Dominican Republic from the deposits formed in the late Early Miocene, ca. 16 Ma. A new species, Polymera (Polymera) alexanderi sp. n. of the dipteran family Limoniidae is described from this amber. This new limonid belongs to the genus Polymera Wiedemann, 1820 with 63 extant species described mostly from South America. Only three fossil species are known so far from Dominican and Baltic amber.

Chemical and spectroscopic signatures of resins from Sumatra (Sarolangun mine, Jambi Province) and Germany (Bitterfeld, Saxony-Anhalt)

Fossil resins from Miocene coal deposit (Sarolangun mine, Jambi Province, Sumatra, Indonesia) have been analysed using spectroscopic methods: Raman Spectroscopy (RS), Fourier Transform-Infrared Spectroscopy (FT-IR), 13C Nuclear Magnetic Resonance (13C NMR), Fluorescence Spectroscopy (FS), and Gas Chromatography–Mass Spectrometry (GC–MS) in order to describe their diagnostic features. Simultaneously, glessite, a fossil resin from Upper Oligocene Bitterfeld deposit (Saxony-Anhalt, Germany), originating from similar botanical sources (i.e. angiosperms) was tested with the same analytical methods in order to find similarities and differences between the resins. The resins differ in colour, transparency and amounts of inclusions (resins from Sumatra—yellow, and transparent with few inclusions; glessite—brown–red, translucent with wealth of inclusions). In general, the IR and RS spectra of these resins are very similar, probably because the glessite colour-changing additives can be very subtle and non-observable in the infrared region. The RS spectra revealed also a slight difference in intensity ratio of the 1650/1450 cm−1 bands (0.56 and 0.68 for Sumatra and Germany resins, respectively), indicating a differences in their maturation process. The resins from Sumatra seem to be more mature than glessite from Germany. The excitation–emission (EM–EX) and synchronous spectra showed unique, chemical compositions of these resins, which are different one from another. The GC–MS data for Sumatran resins, dominated by sesquiterpenoids and triterpenoids (amyrin), confirmed their botanical origin (angiosperms as their biological affinities). The sesquiterpenoid biomarkers with cadine-structures suggested the glessite underwent more advanced polymerization processes, which does not correlate with its RS spectrum. The geological factors, the environmental conditions of resin deposition, and later various diagenesis processes may have influenced the maturation and crosslinking of compounds. Despite the genetic similarity of the resins from various part of the world, Sumatra and Germany, advanced techniques such as Gas Chromatography–Mass Spectrometry and Fluorescence Spectroscopy were the most useful to find the differences between them. These differences are predominantly a result of different diagenetic transformations of the resins.

A new species of Bruchomyiinae (Diptera: Psychodidae) from Baltic amber

Bruchomyiinae is one of seven subfamilies of Psychodidae. This small group comprises fewer than 60 extant species distributed mainly in tropical and sub-tropical regions (Wagner & Stuckenberg 2016). All life stages of these flies are closely tied to forest environment (Fairchild 1952; Stuckenberg 1962) and as a result, bruchomyiines are frequently preserved in fossil resins. The first fossil member of this subfamily was described from Baltic amber (45 Ma) (Meunier 1905) and Burmese amber (100 Ma) is the oldest fossil resin in which representatives of Bruchomyiinae have been found (Stebner et al. 2015; Wagner 2017; Skibińska et al. 2019). Due to the relative scarcity of this subfamily in Baltic amber, any new specimens are of great interest. Up till now, there are only 12 bruchomyiine species described from Baltic amber. Wagner (2017) completed a revision of fossil Bruchomyiinae and proposed the genus Hoffeinsodes to include the species having male genitalia with gonocoxites fused with hypandrium. In this genus, he classified six species reported exclusively from Eocene Baltic amber: H. bifida Wagner, 2017, H. cubicula Wagner, 2017, H. longicauda Wagner, 2017, H. obtusa Wagner, 2017, H. reducta Wagner, 2017 and H. hoffeinsi (Wagner, 2006) transferred from Nemopalpus (Wagner, 2006). Here, we describe a new species belonging to this genus.

A Study on the Formation Environment of the La Cumbre Amber Deposit, from Santiago Province, the Northwestern Part of the Dominican Republic

The amber-bearing coaly shale from the La Cumbre deposit (Cordillera Septentrional, Dominican Republic) contains a large quantity of altered, coalified plant detritus. The coals in these shales are in the transition stage from meta-lignite to subbituminous coals. They are composed mainly of inertinite macerals such as fusinite, semifusinite, macrinite and secretinite. Fossil resin found in the deposit occurs in two forms: detrital grains up to several centimetres in size (type I) and very fine authigenic grains, of a few micrometers in size, inside the humic laminae (type II, resinite). The detrital fossil resins are transparent, with few mineral and organic inclusions. In their composition they contain sulfides, which may come from sulfate reduction, inclusions of plants and/or insects or be caused by volcanic activity developed in surrounding coal series. The resinites are strongly saturated with various inclusions and spatially associated with framboidal pyrite aggregates. Both fossil resin types were probably deposited in a shallow coastal lake environment in the zone bordering the floodplain of the river, with periodic floods. The marine environment conditions, which were progressively changing from oxidizing to reducing, are likely associated with the formation of the fossil resin.

PALEOENVIRONMENTAL AND BIOSTRATIGRAPHIC IMPLICATIONS OF ECHINODERM OSSICLES TRAPPED WITHIN BURMESE AMBER

ABSTRACT Marine organisms are uncommonly preserved in amber. Recently, they were reported to be associated with Burmese amber. However, most of specimens from previous reports were preserved on the amber surface or within the sediment surrounding the amber. Based on X-ray tomography and thin-section optical microscopy of Burmese amber, we report here the first genuine and unambiguous evidence of inclusion of crinoid ossicles preserved in the fossil resin. Preservation of this exclusively marine group in amber gives insights into the paleoenvironment of the crinoid-amber association and provides additional evidence to support previous observations of shallow-water stalked crinoids from the mid-Cretaceous, when many stalked crinoids started to shift offshore due to increased predation pressure during the Mesozoic Marine Revolution. Crinoid remains, represented by disarticulated stem and arm ossicles assignable to Isocrinus cf. legeri (Repelin), point to a mid-Cretaceous age for the Burmese amber and support some previous hypotheses suggesting a close proximity between the resin-producing trees and seawater.

Cretaceous beetles (Insecta: Coleoptera) in amber: the palaeoecology of this most diverse group of insects

Beetles, the most successful group of invertebrates on Earth, have a worldwide distribution and an outstanding fossil record. In addition, they are well known as inclusions in fossil resin. In historical studies of fossil material, specimens were often named and described without placing the taxa in an ecological context. However, the research philosophy for fossil beetles has changed over the past few years. In this article, we summarize the palaeoecological interpretations of fossil beetles from Cretaceous ambers, which includes species from 69 families, most of which were described during the last 3 years. By analysing current habits of those families, we argue that saproxylicity was the most common feeding strategy for these fossil beetles. More specifically, fungivorous species appear to dominate. In contrast, we find only anecdotal evidence for the presence of wood-boring groups, and it is thus necessary to identify alternative abiotic or biotic processes that are responsible for the copious resin production at this time. Finally, the recent description of some beetles as gymnosperm pollinators during the Cretaceous lends more weight to the importance of amber studies in addressing the role of beetles in the evolution of pollination strategies.

Preparation of small-sized 3D amber samples: state of the technique

Preparation of a piece of amber is an inevitable step for any paleontologist working with this precious medium. To see the life-like detail of a biological inclusion, the fossil resin itself has to be trimmed to the minimum, then surfaces polished flat for viewing of the fossil, preferably from all sides. This concerns inclusions of any size, but the smallest—mites, collembolans, scale insects and others—are the most challenging to the abilities of the human hand. Making a millimeter-large cube of a brittle material containing an unscathed tiny fossil was feasible for only a few artists of amber preparation some ten years ago. Now, with tools and techniques having evolved since, the task is feasible for any attentive preparator after a few days of training. This paper is an account of our progress.