First Record of the Genus Cartorhynchites Voss, 1958 (Coleoptera: Rhynchitidae) from Eocene Baltic Amber with a List of Fossil Tooth-Nosed Snout Weevils.

A new species of the genus Cartorhynchites (Rhynchitini, Rhynchitina) is described from Baltic amber. Cartorhynchites groehni Legalov, Bukejs et Alekseev sp. n. differs from C. struvei Zherikhin, 1992 from the Miocene of Germany in its smaller body size (2.6 mm), strongly convex eyes, narrower pronotum and wide elytra, and dark brown legs. A new species is studied and illustrated in detail using X-ray micro-computed tomography (µCT). It is the earliest fossil record of subtribe Rhynchitina. A list of fossil Rhynchitidae was compiled. A key to species of Rhynchitidae in Baltic amber was given. Fossil finds of the family Rhynchitidae were discussed. The assumption was made that the Recent distribution range of the genus Cartorhynchites is within the range of its host plant of the genus Symplocos. Probably, a new Eocene species developed on Symplocos kowalewskii, and the Oligocene C. struvei was associated with Symplocos myosotis (Unger).

Morphological and organic spectroscopic studies of a 44-million-year-old leaf beetle (Coleoptera: Chrysomelidae) in amber with endogenous remains of chitin.

This study details the quality of preservation of amber deposits in the Eocene. Through Baltic amber crack-out studies using Synchrotron Micro-Computed Tomography and Scanning Electron Microscopy it was found that the cuticle of a specimen of leaf beetle (Crepidodera tertiotertiaria (Alticini: Galerucinae: Chrysomelidae)) is exceptionally well preserved. Spectroscopic analysis using Synchrotron Fourier Transform Infrared Spectroscopy suggests presence of degraded [Formula: see text]-chitin in multiple areas of the cuticle, and Energy Dispersive Spectroscopy supports the presence of organic preservation. This remarkable preservation is likely the result of several factors such as the favourable antimicrobial and physical shielding properties of Baltic amber as compared to other depositional media, coupled to rapid dehydration of the beetle early in its taphonomic process. We provide evidence that crack-out studies of amber inclusions, although inherently destructive of fossils, are an underutilised method for probing exceptional preservation in deep time.

A new species of Melipriopsis Kirejtshuk, 2011 (Coleoptera: Nitidulidae: Meligethinae) from the Eocene Baltic amber.

Melipriopsis baltica sp. nov. is described and illustrated from the Eocene Baltic amber. The described holotype (female) of this species has the fully exposed ovipositor with characters similar (general outline, configuration of lobes of the gonocoxites, and disposition of styli) to those in the extant members of the subfamily Meligethinae.

A new fossil species and new record of Atomaria Stephens (Coleoptera: Cryptophagidae) from Eocene Baltic amber.

Based on well-preserved specimen in Eocene Baltic amber, Atomaria (Anchicera) propinqua sp. nov. is described and illustrated. It is the sixth fossil species of Atomaria Stephens, 1829 reported from fossil resins. In addition, a new fossil record of A. (Anchicera) alekseevi Lyubarsky et Bukejs, 2022 from Baltic amber is presented.

Extant genus of flat bark beetle (Coleoptera: Silvanidae) with a present-day Australian-southern South American disjunction discovered in Eocene Rovno amber.

Austronausibius aenigmatista sp. nov., the first fossil silvanid beetle belonging to the Recent genus Austronausibius Halstead distributed in Australia and southern South America, is described from late Eocene Rovno amber. The new fossil species is illustrated and compared with related extant and morphologically close extinct taxa. A key to species of fossil Silvanidae known from Eocene East European amber (Baltic and Rovno) is provided.

Eustrophus praecursor sp. nov.: the first Eocene species of Eustrophinae (Coleoptera: Tetratomidae) from Baltic amber.

Based on well-preserved specimen in Baltic amber (the Kaliningrad Region, Russia), a new polypore fungus beetle of the extant Holarctic genus Eustrophus Illiger, E. praecursor sp. nov. is described and illustrated. It is the first described Cenozoic member of the subfamily Eustrophinae. This fossil record expands the diversity of Tetratomidae known to occur in the Eocene amber forest. A checklist of described fossil Tetratomidae is provided.

Two new fossil species of the genus Atomaria Stephens (Coleoptera: Cryptophagidae) from Eocene European amber with a key to species described from fossil resins.

Two new extinct species of the genus Atomaria Stephens, 1829 are described and illustrated: A. (Anchicera) alekseevi sp. nov. from Baltic amber and A. (Anchicera) perkovskyi sp. nov. from Rovno amber. A key to extinct Eocene species of Atomaria is provided.

The first described darkling beetle of the tribe Metaclisini (Coleoptera: Tenebrionidae) from Eocene Baltic amber.

The description of an extinct species of Metaclisa Jacquelin du Val, 1861 (Tenebrionidae) is presented. This genus and the tribe Metaclisini are recorded as fossils for the first time, from Eocene Baltic amber. The new species Metaclisa ottoi sp. nov. belongs to the subgenus Trichometaclisa subgen. nov. and differs from all other Metaclisini in possessing short, fine recumbent setation on the pronotum and elytra; in addition, the prosternal process in Metaclisa ottoi sp. nov. is roundly bent down and weakly projected behind the procoxae, which differs from extant species.

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 (CT). 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.

First fossil representative of Cerylonidae (Coleoptera: Coccinelloidea) described using X-ray micro-computed tomography, from Eocene Baltic amber.

Based on material originating from five amber collections of Eocene Baltic amber, Protostomopsis pandema gen. et sp. nov. is described and illustrated using X-ray micro-computed tomography. It is the first formally described extinct species of Cerylonidae, and the first known Palaearctic representative of the subfamily Ostomopsinae. As such, the new species extends the temporal range of the family Cerylonidae by approximately 45 Ma.

The First Ptilodactyla Illiger, 1807 (Coleoptera: Dryopoidea: Ptilodactylidae) Described from Eocene Baltic Amber.

The beetle family Ptilodactylidae contains more than 500 extant species; however, its fossil record is scarce and remains understudied. In this study, we describe a new species of Ptilodactylidae, Ptilodactyla eocenica Kundrata, Bukejs and Blank, sp. nov., based on a relatively well-preserved specimen from Baltic amber. We use X-ray microcomputed tomography to reconstruct its morphology since some of the principal diagnostic characters have been obscured by opaque bubbles. It is the third ptilodactylid species described from Baltic amber, and the first one belonging to the subfamily Ptilodactylinae. Additionally, we summarize the classification, diversity, and distribution of both extinct and extant Ptilodactylidae.

The invisibile becomes visible: X-ray micro-CT reconstruction of emAneurus/em emdamzeni/em sp. nov. (Hemiptera: Heteroptera: Aradidae) from Eocene Baltic amber.

The subfamily Aneurinae of the flat bug family Aradidae (Hemiptera: Heteroptera) contains about 150 extant species assigned to seven genera, and seven fossil species of which six were described from Eocene Baltic amber and one from Cretaceous Burmese amber. A new species Aneurus damzeni sp. nov. from Baltic amber is described and illustrated using X-ray micro-computed tomography (µCT) reconstructing concealed morphological characters. A key to all five extant and fossil Aneurinae species with triangular scutellum is provided.

Fossil Melandryidae (Coleoptera: Tenebrionoidea) from Eocene Baltic amber of the Sambian peninsula: new genus, six new species, new records and key to described taxa.

Six new extinct representatives of the family Melandryidae, namely Electroxylita chronographica gen. et sp. nov., Madelinia capillata sp. nov., Microscapha kugelanni sp. nov., Phloiotrya inmarinata sp. nov., Symphora pollocki sp. nov., and S. glaesonauta sp. nov. are described from inclusions in Eocene Baltic amber. Twenty-eight additional fossil specimens of melandryid beetles belonging to ten species are reported. A list of Melandryidae described from Baltic amber is compiled and an identification key is provided.

The first fossilized comb-clawed beetle of the genus Asiomira Dubrovina, 1973 (Coleoptera: Tenebrionidae: Alleculinae) from Baltic Amber and notes on the distribution of extant species of the genus.

A new species of comb-clawed beetles of the genus Asiomira Dubrovina, 1973 (A. dubrovinae sp. n.) is described from the Eocene Baltic amber. This newly descovered fossil species displays typical generic characters and is the most similar to the extant Asiomira ophtalmica (Seidlitz, 1896). Both species share a similar shape of the pronotum and the flattened posterior angles of the pronotal disc. Asiomira dubrovinae sp. n. can be distinguished from A. ophtalmica by the smaller body size (4.8 mm in contrast to 68.12 mm), more serrate antennomeres, and finer and sparser pronotal punctation. Extant species of the genus are distributed in the arid landscapes of Central Asia with the highest diversity occurring in Tajikistan. Therefore the discovery of a new fossil species from Eocene Baltic amber suggests that Asiomira could have a wider range, and the modern distribution of this group is the result of a later secondary expansion of the ancestral representatives that survived in mid-mountain areas with arboreal and shrub vegetation. Relevant corrections to the distribution of extant species, Asiomira ophtalmica (Seidlitz, 1896) and Asiomira firjusana (Dubrovina, 1973), are given.

X-ray micro-computed tomography reveals a unique morphology in a new click-beetle (Coleoptera, Elateridae) from the Eocene Baltic amber.

Beetle fossils are a rich source of information about the palaeodiversity and evolutionary history of the order Coleoptera. Despite the increasing rate of fossil research on click-beetles (Coleoptera: Elateridae), the most diverse group in the superfamily Elateroidea, their fossil record has remained largely unstudied. This may be caused by the combination of their rather uniform external morphology and the suboptimal state of preservation and visibility in most fossil specimens. Here, we used X-ray micro-computed tomography to reconstruct the morphology of an interesting click-beetle from Eocene Baltic amber, which had some principal diagnostic characters obscured by opaque bubbles and body position. Our results suggest that the newly described Baltelater bipectinatus gen. et sp. nov. belongs to tribe Protelaterini within subfamily Lissominae. Since Protelaterini have a predominantly Gondwanan distribution, our discovery is of a great importance for the historical biogeography of the group. Very distinctive are the bipectinate antennae with 11 antennomeres and with rami beginning on antennomere IV, which are not found in any recent Elateridae. The discovery of a new click-beetle lineage from European Eocene amber sheds further light on the palaeodiversity and historical diversification of the family as well as on the composition of the extinct amber forest ecosystem.

The first described fossil species of Litargus Erichson (Coleoptera: Mycetophagidae) from Eocene Baltic amber examined with X-ray microtomography, and new records of Crowsonium succinium Abdullah, 1964.

A new species of Mycetophagidae belonging to the genus Litargus, namely L. (Litargosomus) dantiscensis Alekseev, Kupryjanowicz et Bukejs sp. nov., is described and figured from Eocene Baltic amber using X-ray micro-computed tomography (µCT). Three additional specimens of a mycetophagid beetle that is rather common in Baltic amber, Crowsonium succinium Abdullah, are also reported. Prototoma striata Heer, which was originally placed in Mycetophagidae, is discussed based on its original description and illustration: it is proposed that the position incertae sedis within Coleoptera be given to this Early Jurassic fossil. Consequently, the records of Mycetophagidae from Eocene European amber should be considered the earliest occurrence of the family known to date.

The oldest fossil darkling beetle of the genus Neomida Latreille, 1829 (Coleoptera: Tenebrionidae) from Eocene Baltic amber examined with X-ray microtomography.

Based on a single well-preserved specimen from Eocene Baltic amber, a new tenebrionid beetle Neomida groehni Nabozhenko et Bukejs sp. nov. (Diaperinae: Diaperini) is described and illustrated using phase-contrast X-ray microtomography. This oldest representative of the genus differs from all known extant and extinct congeners by the dorsally very weakly convex pronotum with undulate lateral margins (while other Neomida have a pronotum that is strongly convex along its transverse axis, with evenly rounded lateral margins); distinct, right posterior angles of pronotum; and elevated sutural area of the elytra.

A new fossil Eurypinae genus and sexual dimorphism in the representatives of Omineus (Coleoptera: Mycteridae) from Tertiary amber of Europe.

Europoeurypus inglaeso gen. et sp. nov. is described from Eocene Baltic amber found on the Sambian Peninsula, Kaliningrad Region, Russia. Four additional specimens of mycterid beetles from collections of Baltic amber are reported. The secondary sexual characters and sexual dimorphism in the Eocene representatives of the genus Omineus Lewis, 1895 are documented for the first time and examined using X-ray micro-computed tomography (µCT). The studied Omineus male specimens were attributed to the fossil species Omineus febribilis Alekseev, Pollock Bukejs, 2019. A key to fossil species of Eurypinae from Eocene ambers is provided and several aspects of the biogeography of the subfamily Eurypinae are discussed.

Groehnaltica batophiloides, a new genus and species of flea-beetles (Coleoptera: Chrysomelidae) from Baltic amber, described using X-ray microtomography.

Based on a well-preserved specimen from Eocene Baltic amber, Groehnaltica batophiloides gen. nov. and sp. nov. (Coleoptera: Chrysomelidae: Galerucinae: Alticini) is described and illustrated using X-ray micro-computed tomography (µCT). The new monotypic genus is compared with fossil and extant flea-beetle genera. In the extant Eurasian fauna Groehnaltica shows most similarity to Batophila Foudras, 1859. However, it is also similiar to a Palaeotropical group of genera, including Bikasha Maulik, 1931, and Lanka Maulik, 1926. Groehnaltica batophiloides is the tenth member of Alticini to be described from Baltic amber, adding to our understanding of the evolutionary history of this diverse group of beetles.

A new fossil species of Bolitophagini (Coleoptera: Tenebrionidae) from Baltic amber suggests the genus Eledonoprius Reitter is persistent in the Western Palaearctic since the Tertiary.

The first fossil representative of Eledonoprius Reitter, E. incoronatus sp. nov., is described from Eocene Baltic amber. The genus is associated with old-growth forests in the modern Western Palaearctic Region and apparently has persistent in this Region since the Paleogene.