Metrics details Of the early Eocene amber deposits known across the world Belgian amber has been mostly absent from the relevant literature We reinvestigated amber held in the palaeobotanical collection of the Royal Belgian Institute of Natural Sciences which derived from three localities in Belgium that originated from two geographical areas (Leval-Trahegnies and Orp-le-Grand) Using Fourier transform infrared (FTIR) spectroscopy we show the close chemical relationship of Belgian amber to the early Eocene Oise amber from the Paris Basin and highlight the potential effect of weathering on the amber chemistry The amber derives from a very similar botanical source as the Oise amber (Combretaceae or Leguminosae-Caesalpinioideae) The two Leval-Trahegnies localities provided amber that exhibit different stages of weathering (heavily fissured and crazed The Orp-le-Grand locality provided the least weathered amber with one amber piece containing two inclusions: a mite and a new genus and species of hemipteran (Cativolcus uebruum gen and a second one that preserved the impression of insect wings pressed into the surface These specimens have also since been lost and interest in the amber waned Here we describe historically collected Belgian amber from three localities in two geographical areas (Leval-Trahegnies and Orp-le-Grand) now held in the palaeobotanical collection of the Royal Belgian Institute of Natural Sciences The amber originating from the two Leval-Trahegnies localities was found to lack inclusions and to be very weathered the Orp-le-Grand locality yielded previously unrecorded inclusions; a new genus and species of true bug on the surface of one stalactite-shaped amber piece there are the impressions of insect wings preserved The chemical analyses of these early Eocene Belgian ambers show their close relationship to each other and to the contemporaneous Oise amber from the Paris Basin implying the same or a very similar source plant (Combretaceae or Leguminosae-Caesalpinioidceae) for all these different amber localities with the Eocene amber-bearing localities represented in the RBINS collections (starred) amber from Sablière La Courte à Leval (M5) this is the most darkened and fissured amber from the three localities with some variations in colour; middle Row amber from Trieu de Leval (M6); lowest row amber from Orp-le-Grand showing the lightest colour of amber present from each of the three localities As the ambers were washed clean before or at the time they came into the collections there is no additional material such as the host sediment available for palynological dating This is the only amber in the RBINS collections that yielded new fossil inclusions and impressions (a) Mean FTIR spectra by locality for the Eocene ambers from Belgium (Leval M5 = La Courte à Leval (M5) (b)–(d) Multivariate analysis of amber spectra from Belgium Leval M5 = La Courte à Leval (M5) and Orp-le-Grand) and from Oise (France) using FTIR-ATR spectroscopy: (b) Principal components analysis showing PC1 vs note the two triangles for Leval M6 (= Trieu de Leval (M6) – the more central one is composed of two triangles giving the appearance that one sample is missing when in fact two are indistinguishable; (c) loadings for PC1; (d) mean cluster analysis by locality but they all share the same bulk chemistry In the multivariate analyses applied to the dataset (both the dataset and R scripting available in the Supplementary Dataset) 89.2% of the variance was accounted for by two principal components (percentage of variance for PC1: 74.52% so no further principal components were needed to describe the variation A baseline correction did not improve the results and was not needed as no baseline drift was observed The intensity of the peaks at 2935 cm−1 and 2848 cm−1 linked to methylene groups and the large (negative) peak at 1693 cm−1 caused by C–O double bonds in carboxyl groups of resin acids just highlight the band intensity differences between the samples at those wavenumbers These differences are most likely attributable to either the slightly different taphonomy of the ambers or their subsequent geological history and varying levels of weathering/oxidation as noted in the different colourations and levels of oxidised appearance of the ambers from the different localities This could be because these three amber samples looked more alike in terms of colouration and crazing than the other ambers tested Arthropod fossils (inclusions and impression) in Belgian amber (c) detail of genitalia (45 stacked images) (e) impression of insect wings on amber surface This adds independent evidence that these Belgian and French localities were of comparable age and with similar environments and ecosystems LSID urn:lsid:zoobank.org:act:005BA54B-E6AA-486E-8775-B1176305890D Type species: Cativolcus uebruum Szwedo sp leader of a Belgic tribe of north-eastern Gaul (Gallia Belgica) Holotype: (Fig. 3a–c); Specimen number BE-RBINS-ENT-AMBER-IG-34605 Body length about 2.5 mm; body oblong oval mesonotum and tegmina covered with moderately short directed posteriad; hairs on pronotum and corium lighter than background about 2.4 times as long as wide; jugae carinate Combined length of antennomeres II and IV merely exceeding length of antennomere II posterior margin shallowly concave; disc of pronotum smooth Scutellum (mesonotum) wider at base than long commisura clavale about as long as mesocutellum Tarsi pseudo-trimerous (border between mid- and apical tarsomeres not distinct) (Fig. 3a–c; Supplementary figs. S4, S5) LSID urn:lsid:zoobank.org:act:2D090065-1895-476A-A0E1-05424564DE7B Specific epithet from Gallic stem ‘uebru-’ – meaning amber deposited in the Royal Belgian Institute of Natural Sciences Slightly smaller (2.12 mm long) than Cativolcus prokopi (2.25–2.5 mm); compound eyes with short setae between ocelli (compound eyes bare in C frons and clypeus with protruding setae (no such setae on head of C prokopi); ratio of corium to cuneus length ca prokopi); metafemur length/width ratio 3 (3.4 in C General colouration light brown to brownish pronotum brownish with dark brown punctuation at bases of setae narrower than pronotum about 2/3 of its width Head with compound eyes about 2.6 times wide as long (0.225 mm) contiguous with anterior margin of pronotum and with anterior margin of vertex about twice as long as wide; base of clypeus located slightly above than half eye height; mandibular plate (jugae) carinate Antennal fossa situated at base of maxillary plate slightly widening apicad; antennomere II the longest longer than diameter of antennomere; III antennomere 0.281 mm long covered with dense slightly protruding setae slightly exceeding apices of metacoxae; apical segment subequal to preapical one (ca lateral margins distinctly diverging posteriad Pronotum about 2.8 times as wide (0.82 mm) as long in mid line (0.29 mm); about 1.23 times as long as head in total wider at base (0.60 mm) than long in mid line (0.39 mm) Scutellum lighter than pronotum and corium Mesopleura with a few short setae in upper portion with scent gland area (?) delicately granulose and slit-like opening mid-and apical tarsomeres merely separated Mesofemur slightly longer than profemur ca Metatarsus longer than pro- and mesotarsus about 2.84 times as long as cuneus (0.36 mm) directed posteriad and lighter than background setae surface delicately crumpled; membrane 1.59 times as long as wide covered with long setae; ventral margin with subtriangular process medially suggested splitting of Isometopinae and Cylapinae in the earliest Cretaceous alas Psallopinae were not taken to the analysis The recent Psallopsinae live under very different climates even though all are warm therefore it could be inferred that Cativolcus uebruum gen which is in concordance for the palaeoconditions reconstructed for the fossil site and was present at a time of global warming when the resin was originally exuded entrapping the specimen Early Eocene amber held in the palaeobotanical collection of the RBINS is from three localities across two geographical areas of Belgium Using FTIR-ATR we showed these ambers to be chemically very similar to each other and to the contemporaneous Oise amber from France suggesting that they share the same or a very similar botanical source (Combretaceae or Leguminosae-Caesalpinioideae) Ambers from the two different deposits of Leval-Trahegnies are more weathered in appearance (darkened and heavily crazed surfaces of the amber pieces) and they lack inclusions less weathered as it is generally lighter in colour and less crazed in appearance than the Leval-Trahegnies derived amber Although a smaller volume of amber is present from Orp-le-Grand two inclusions were discovered in one piece plus the impression of insect wings on the surface of another The inclusions are a mite and a new genus and species of hemipteran (Psallopinae) Cativolcus uebruum representing the shared oldest occurrence of the Psallopinae with that reported from the relatively palaeogeographically close by Oise amber from the Paris basin The former amber-bearing localities have since been closed and filled in and thus cannot currently be accessed Notes from the RBINS collections record the M5 locality as ‘La Courte à Leval In the present analyses it is referred to as ‘Leval M5’ This amber was found in clay lenses in the sand quarry at La Courte à Leval The whole deposit in the museum is marked with RBINS number Plateau PBot 6754 (67,939) and IG 6978 There is 4902 g of amber that has been washed and graded by size The M6 locality is listed as ‘Trieu de Leval Morlanwelz 6 Carrières d’argile plastique du Trieu de Leval à Leval-Trahegnies In the present analyses it is referred to as ‘Leval M6’ The whole deposit in the museum is marked with RBINS number Plateau Pbot 6807 (67,903) and IG 7021 2988 g of amber in total was recovered from a clay quarry This amber locality is noted as ‘Orp-le-Grand In the present analyses it is referred to as ‘Orp le Grand’ The whole deposit from the Walloon Brabant Province in the museum is marked with RBINS number Plateau PBot 6808 and IG 9875 sorted and selected by the seller of the amber who was the foreman of the quarry The amber from this locality was sold to the museum in three separate lots (sometimes with other fossil materials) The IG number for Orp-le-Grand amber shows that it corresponds to the purchase on December 2 reptile and fish bones as well as fossil resin from the brick and tile factory of Orp-le-Grand (pers before minor and careful grinding and polishing of the specimen Grinding and polishing manually with wet silicon carbide papers (grit from 25.8 to 5.0 μm particle size; Struers company USA) was done to remove scratches and to create a smooth surface parallel to the inclusion The amber inclusions were examined with a Stereo Discovery V8 dissection microscope (Carl Zeiss Germany) and an AxioScope A1 compound microscope (Carl Zeiss Germany) using incident and transmitted light simultaneously Images were taken with Canon EOS 5D digital cameras (Canon Additional photographs were taken at the Laboratory of Evolutionary Entomology and Museum of Amber Inclusions at the University of Gdansk equipped with a Canon EOS 90D digital camera (Cannon Tokyo The images were then stacked using HeliconFocus version 6.3.3 Pro (Helicon Soft Some images are composites of several stacked images stitched together using Adobe Photoshop the images were taken using a Stemi 508 dissecting microscope (Carl Zeiss Germany) with incident light and the images stacked using Photoshop Drawings were made with the use of camera lucida attached to the Olympus BX51 and Olympus SZX10 microscopes then readjusted with the CorelDrawX7 package (Corel The ATR crystal and anvil were thoroughly cleaned between each measurement The spectra were visualized using SpectraGryph v1.2.13 The spectra were then subjected to statistical analyses For the multivariate data exploration and visualization principal component analysis (PCA) and cluster analysis were used64 The cluster analysis was run using the Euclidean distance and with the unweighted pair group method with arithmetic mean (UPGMA) linkage algorithm and the locality-mean spectra were also subject to this to simplify relationships between the amber samples from the different localities The datasets and the R scripts are available as Supplementary data This publication and the nomenclatural acts it contains are registered in ZooBank, the proposed online registration system for the International Code of Zoological Nomenclature (ICZN). The ZooBank LSIDs (Life Science Identifiers) can be obtained and the associated information viewed using any standard web browser by appending LSID to the prefix ‘http://zoobank.org/’ The LSID for this publication is: urn:lsid:zoobank.org:pub:BB11FBB1-5FEC-4994-A8B2-0DAD2D082B70 All data and R codes generated and analysed during this study are supplied as files for download and so are included in this published article and Supplementary Figs 1–4 are available as a pdf download for this publication New early Eocene vertebrate assemblage from western India reveals a mixed fauna of European and Gondwana affinities Biogeographic and evolutionary implications of a diverse paleobiota in amber from the early Eocene of India Diverse paleobiota in early Eocene Fushun amber from China New genus of minute Berothidae (Neuroptera) from Early Eocene amber of British Columbia Un gisement Sparnacien exceptionnel à plantes In Biodiversity of fossils in amber from the major world deposits (ed Origine de l’ambre des faciès Sparnaciens (Éocène inférieur) du Bassin de Paris: le bois de l’arbre producteur An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics The Paleocene-Eocene Thermal Maximum: A perturbation of carbon cycle and biosphere with Implications for the future Un insecte névroptère dans une résine du Landénien de Léau (Brabant) Note préliminaire sur la résine fossile de Leval Études sur les végétaux fossiles du Trieu de Leval (Hainaut) 39−43 (Brussels Remarques sur la constitution de l’ambre fossile Sur la découverte d’une flore fossile dans le Montien du Hainaut Compte rendu des excursions de la Session extraordinaire de la Société belge de Géologie de Paléontologie et d’Hydrologie dans le Hainaut et aux environs de Bruxelles Les végétaux fossiles du Trieu-de-Leval (Hainaut) High-resolution holostratigraphy of Middle Paleocene to Early Eocene strata of Belgium and adjacent areas reassessment of the morphology and taxonomic status of ‘Crocodylus’ depressifrons Blainville Crocodyloidea) based on the Early Eocene remains from Belgium Systematics and diversity of the giant soft-shelled turtles (Cryptodira Trionychidae) from the earliest Eocene of Belgium Initiation à la Paléobotanique Stratigraphique de la Belgique: Guide de la salle des végétaux fossiles (Institut royal des sciences naturelles de Belgique and organic carbon isotope evolution in lagoonal Paleocene-Eocene boundary settings in North Belgium Rapid Asia–Europe–North America geographic dispersal of earliest Eocene primate Teilhardina during the Paleocene-Eocene Thermal Maximum Current status of chronostratigraphic units named from Belgium and adjacent areas (eds.) 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R package version 1.1–2. https://CRAN.R-project.org/package=RColorBrewer (2014) Introduction to Multivariate Statistical Analysis in Chemometrics (CRC Press Taylor & Francis Download references We thank the scientific colleagues at the RBINS for their support and interest in this work We warmly thank Vincent Perrichot (University Rennes) for providing the Oise amber samples and Burkard Schmidt (University of Göttingen) for continued access to We thank Thierry Smith for his invaluable insights and we very much appreciate his generous review strengthening this manuscript and an anonymous reviewer for comments We also thank Ninon Robin for help and discussions on Belgian amber Access to the RBINS collections for LJS was funded by the Synthesys Programme Open access funding is provided by University of Vienna These authors contributed equally: Leyla J Laboratory of Evolutionary Entomology and Museum of Amber Inclusions Department of Invertebrate Zoology and Parasitology Royal Belgian Institute of Natural Sciences Evolution and Diversity Dynamics Laboratory (EDDy Lab) FTIR and statistical analyses and interpretations inclusion search and provided all the support for tracing and translating the historical documentation and rediscovering the original amber localities stabilized and photographed the mite and the holotype of the hemipteran described the holotype and undertook the taxonomic treatment and all authors contributed to the final version The authors declare no competing interests Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations Download citation DOI: https://doi.org/10.1038/s41598-024-64286-z Anyone you share the following link with will be able to read this content: a shareable link is not currently available for this article Sign up for the Nature Briefing newsletter — what matters in science