Eocene Baltic Amber Research Articles

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.

New Tribe Palaeoanoplini trib. nov. (Coleoptera: Curculionidae) in Baltic Amber

A new tribe, Palaeoanoplini trib. nov., with a new genus, Palaeoanoplus gen. nov., and a new species, P. horridus sp. nov., of the subfamily Curculioninae are described from the Late Eocene Baltic amber. The new tribe is close to the Recent tribe, Anoplini; however, it differs from Anoplini by its tibia without uncus, as well as by tarsal claws present, without teeth, prosternum with postocular lobes, and body covered with long erect setae.

Paleotelmatoscopus, a proposed new genus for some fossil moth flies (Diptera, Psychodidae, Psychodinae) in Eocene Baltic amber, with description of a new species.

Few species of Baltic amber Psychodinae have been described to date. Some were incorrectly classified in Pericoma Walker based on an early, broad definition of the genus and holotypes were not specified. We examined approximately 50 specimens of Baltic amber Psychodinae in addition to reviewing the original series studied by Fernand Meunier. Lectotypes for Pericoma formosa Meunier and P. speciosa Meunier are designated and Paleotelmatoscopus gen. nov. is proposed to include P. formosa and P. madrizi sp. nov. Characters included in the diagnosis of this new genus and species have implications for future descriptions of Baltic amber Psychodinae. Parts of the head capsule, such as antennae, are often well-preserved and visible, and can be useful for separating species. However, these character complexes are prone to homoplasy and should not be used alone to define genera. Since it is impossible to view internal genitalic characters in fossil species, refinement of generic and species diagnoses based on external morphology is a critical factor in describing the amber fauna.

A new species of extinct genus Electromyiomma Popov amp; Herczek (Hemiptera: Miridae: Isometopinae) from Eocene Baltic amber, with the key to Electromyiomma species.

A new fossil isometopine species, Electromyiomma herczeki sp. nov. is described and illustrated from Eocene Baltic amber. The morphological information of the fossil specimen and the key to the species of the extinct genus Electromyiomma are provided. The restatement of paratype female of E. weitschati is discussed with the support of previous remarks based on antenna structure.

The first described turtle beetles from Eocene Baltic amber, with notes on fossil Chelonariidae (Coleoptera: Byrrhoidea)

Abstract. Chelonariidae, or turtle beetles, are rarely represented in the fossil record. Two new extinct species of this thermophilous coleopteran family, Chelonarium andabata Alekseev and Bukejs sp. nov. and Ch. dingansich Alekseev and Bukejs sp. nov., are described and illustrated from Eocene Baltic amber using X-ray micro-computed tomography (micro-CT). They are the first formally described species of turtle beetles from Eocene Baltic amber and the first known European representatives of this family. Based on modern habitats of the group, the presence of the plants with which their larvae are associated (epiphytic orchids) is proposed in the Eocene amber forest. The Eocene Florissant Formation fossil Chelonarium montanum Wickham, 1914, which was originally placed within Chelonariidae, is discussed based on its original description, and placement as incertae sedis within Byrrhoidea is proposed for this compression fossil (http://zoobank.org/References/C2EE164D-59DD-42FE-937D-B01C78DCD228, last access: 8 February 2021).

Airapus rakovici (Coleoptera: Scarabaeidae: Aphodiinae: Eupariini), a new species from Fujian, China.

The genus Airapus Stebnicka Howden, 1996 currently comprises 26 extant species distributed in the Australian and Oriental zoogeographical regions (Stebnicka Howden 1996; Stebnicka 1998, 2009; Rakovič et al. 2019; Král et al. 2019; Minkina 2020) and one fossil species from the Eocene Baltic amber (Tamutis et al. 2017). Of the continental Southeast Asia, only three species have been known so far: Airapus cechovskyi Král, Mencl Rakovič, 2019 (mainland Malaysia: Kelantan), A. tyri Král, Mencl Rakovič, 2019 (Central Thailand: Phetchaburi Province) and A. sicardi ( Paulian, 1945) (Laos: "Cochinchine: Long Xuyen" and South Vietnam: "Annam: Tanh Hoa") (Paulian 1945; Balthasar 1964; Král et al. 2019). Examination of the material housed in the collections of the Institute of Zoology, Chinese Academy of Sciences, Beijing, China, revealed Airapus material belonging to an undescribed species. Its formal description is presented in this paper. This new species is another, fourth species occurring in mainland Southeast Asia. It is also the first country record from China. The geographical distribution of the genus is now known to the north as far as Fujian Province.

A new fossil Stempellinella from Eocene Baltic amber, with systematic notes and amendment of the generic diagnosis (Diptera: Chironomidae).

Stempellinella gilkai sp. nov., an Eocene non-biting midge of the subfamily Chironominae, tribe Tanytarsini is described on the basis of the adult male. This is the sixth fossil representative of the genus and the fifth described from Baltic amber (~40-45 Ma). The species displays a set of morphological characters typical of the genus. To facilitate a delimitation of fossil Stempellinella, a comparison of the most significant characters is provided. The key features of antenna and hypopygium are discussed in detail. A comparative analysis of both extinct and extant Stempellinella representatives allowed to perform an amendment of the current generic diagnosis. Notes on the genus' palaeoecology and species richness during the Eocene are also included.

A new species of Xyletinus Latreille, 1809 (Coleoptera: Ptinidae: Xyletininae) from Eocene Baltic amber, with a key to known fossil species

A new species of Xyletinus Latreille, 1809 (Coleoptera: Ptinidae: Xyletininae) from Eocene Baltic amber, with a key to known fossil species

A New Genus and Species of Soft-Winged Flower Beetles (Coleoptera, Malachiidae) in Baltic Amber

A new genus and species of soft-winged flower beetles (Coleoptera, Malachiidae), Aliattalus intercalaris gen. et sp. nov., are described in the Late Eocene Baltic amber. The new genus is assigned to the tribe Palpattalini because the male possesses specific structures: an elongated, ventrally curved, domed pygidium with an elongated and bilaciniate apical sternite is combined with large palps, in which the second and third segments are closely adjacent to each other and enlarged. This species in appearance is similar to the genus Palpattalusinus Tshernyshev, 2020, also known in amber: both have similarly fused and enlarged palps with a small cup-shaped first segment, but the apical palpomere in the new species is curved inward and rounded at the apex, rather than elongated to form a tube.

First record of Leptoomus janzeni Gibson (Hymenoptera, Chalcidoidea) from Rovno amber

The large and distinctive chalcidoid wasp Leptoomus janzeni Gibson, 2008, originally described from late Eocene Baltic amber, is newly recorded from coeval Rovno amber (Ukraine) based on a single well-preserved female specimen. Only 66 species of Rovno hymenopterans (49%) are also known from Baltic amber. High resolution photomicrographs and measurements of the specimen are given. Some character states of the new specimen, such as a green metallic coloration, a bare and flat prepectus, location and number of multiporous plate sensillae on the flagellum, sclerotized spur vein of the hind wing, and two metatibial spur are reported in this species for the first time.

<p><strong>A new species of parasitoid wasps (Hymenoptera: Diapriidae: Belytinae) from Eocene Baltic amber</strong></p>

Acropiesta perrichoti sp. nov., a new belytine wasp is described based on a well preserved male specimen from Eocene Baltic amber. This is the second fossil species of this extant genus, known already from the same amber deposit by Acropiesta janzeni Buhl, 2002.

Staminate inflorescences with in situ pollen from Eocene Baltic amber reveal high diversity in Fagaceae (oak family)

Eocene Baltic amber forms the largest amber deposit worldwide; however, its source vegetation and climate are much debated. Representatives of the oak family (Fagaceae) were abundant in the Baltic amber source area based on numerous inclusions of staminate inflorescences or individual florets, previously assigned to Castanea and Quercus. However, the actual generic and infrageneric diversity of Fagaceae from Baltic amber remained unknown. Using flower characteristics and section-diagnostic in situ pollen of staminate inflorescences and detached floret inclusions, we describe 18 fossil-species of Fagaceae making this family by far the most diverse plant family preserved in Baltic amber. We substantiate the occurrence of the Castaneoideae, Quercoideae (Quercus sect. Cyclobalanopsis/Lobatae; Q. sect. Lobatae; Q. sect. Protobalanus), Trigonobalanoideae and the extinct genus Eotrigonobalanus. Among the 18 fossil-species, six are described as new: Q. aimeeana, Q. casparyi, Q. multipilosa, E. campanulata, E. conwentzii, E. longianthera; and one new combination is published: Q. brachyandra (≡ Castanea brachyandra). In addition, a lectotype is designated for the name Quercites meyerianus and neotypes are designated for the names Castanea inclusa and Quercus longistaminea (≡ C. longistaminea). Members of the Fagaceae probably inhabited azonal and zonal vegetation types of the amber source area, including bottomland flood-plains and stream banks (Q. sect. Lobatae), dry habitats (Q. sect. Lobatae, Q. sect. Protobalanus), peaty soils, riparian and swamp forests (Castanopsis, Eotrigonobalanus), as well as mixed mesophytic forests (castaneoids, Quercoideae, trigonobalanoids). Affinities to extant North American and E to SE Asian floras support the recent notion that late Eocene Baltic amber (38–34 Ma) was formed in a warm-temperate climate.

Eco-morphological diversity of larvae of soldier flies and their closest relatives in deep time.

Stratiomyomorpha (soldier flies and allies) is an ingroup of Diptera, with a fossil record stretching back to the Early Cretaceous (the Barremian, about 125 MYA). Stratiomyomorpha includes at least 3,000 species in the modern fauna, with many species being crucial for ecosystem functions, especially as saprophages. Larvae of many stratiomyomorphans are especially important as scavengers and saproxyls in modern ecosystems. Yet, fossil larvae of the group are extremely scarce. Here we present 23 new records of fossil stratiomyomorphan larvae, representing six discrete morphotypes. Specimens originate from Cretaceous amber from Myanmar, Eocene Baltic amber, Miocene Dominican amber, and compression fossils from the Eocene of Messel (Germany) and the Miocene of Slovenia. We discuss the implications of these new records for our understanding of stratiomyomorphan ecomorphology in deep time as well as their palaeoecology.

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 new genus of the tribe Hypulini Seidlitz (Coleoptera: Melandryidae) described from late Eocene Baltic amber.

A new extinct monotypic genus of the false darkling beetles, Madelinia gedanoposita gen. et sp. nov., is described and illustrated based on an inclusion in Baltic amber. The new taxon from a northern European Eocene forest is compared with the morphologically similar extant beetles as well as fossil melandryid beetles found in Baltic amber. The specimen establishes that the tribe Hypulini dates back to at least the Eocene and represents the first fossil genus of the group described. The composition of the tribe is discussed, and its present-day geographic distribution is mapped.

Patching up the past one fossil at a time: A new genus and species of Eulophidae from Eocene Baltic Amber (Hymenoptera, Chalcidoidea)

A new fossil species of Eulophidae, Kressleinius celans, gen. et sp. nov., is described from Eocene Baltic amber. It does not place into any extant genera within Eulophidae due to a lack of distinctive synapomorphies. The results of a morphology-based phylogenetic analysis placed K. celans in Tetrastichinae because of features shared with several genera, including having 6 flagellomeres past the anelli, admarginal setae short, propleura diverging, and a newly described feature of the transepimeral sulcus. This represents the oldest known fossil for the largest family of Chalcidoidea in terms of described species.

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 remarkable new species of the rove beetle genus Anthobium Leach, 1819 from Eocene Baltic amber (Coleoptera, Staphylinidae, Omaliinae).

An unusual new omaliine species, Anthobium alekseevisp. nov., is described and illustrated from Eocene Baltic amber, tentatively placed in the megadiverse genus Anthobium Leach, 1819. A new monotypic species-group is established. The new species can easily be distinguished from other species of the genus by the larger body, shape of the subrectangular pronotum, and the presence of a median carina on the prosternum and large, subtriangular tooth on the inner side of each mesotibia, likely exhibiting a peculiar sexual dimorphism in the male. Based on the study of the specimen with support of microtomographic images, a brief comparative analysis of a new species with described extant species of Anthobium is provided.

On the value of Burmese amber for understanding insect evolution: Insights from †Heterobathmilla - an exceptional stem group genus of Strepsiptera (Insecta).

Burmese amber and amber from other periods and regions became a rich source of new extinct insect species and yielded important insights in insect evolution in the dimension of time. Amber fossils have contributed to the understanding of the phylogeny, biology, and biogeography of insects and other groups, and have also gained great importance for dating molecular trees. Another major potential is the documentation of faunal, floral and climatic shifts. Evolutionary transitions can be well-documented in amber fossils and can reveal anatomical transformations and the age of appearance of structural features. Here, using a new stem group species of Strepsiptera from Burmite, we evaluate this potential of amber insect fossils to assess the current phylogeny of Strepsiptera, with the main emphasis on the early splitting events in the stem group. Amber fossils have greatly contributed to the understanding of the evolution of Strepsiptera in the late Mesozoic and the Cenozoic. †Heterobathmilla kakopoios Pohl and Beutel gen. et sp. n. described here is placed in the stem group of the order, in a clade with †Kinzelbachilla (†Kinzelbachillidae) and †Phthanoxenos (†Phthanoxenidae). †Phthanoxenidae has priority over †Kinzelbachillidae, and the latter is synonymised. The superb details available from this new fossil allowed us to explore unique features of the antennae, mouthparts, and male copulatory apparatus, and to provide a phylogenetic hypothesis for the order. The younger †Protoxenos from Eocene Baltic amber was confirmed as sister to all remaining extinct and extant groups of Strepsiptera, whereas the position of the Cretaceous †Cretostylops in the stem group remains ambivalent. While the value of Burmite and amber from other periods has a recognized impact on our knowledge of the evolution in various lineages, this new fossil does not fundamentally change our picture of the phylogeny and evolution of early Strepsiptera. However, it offers new insights into the morphological diversity in the early evolution of the group.

<p><strong>The first fossil Phloeocharinae Erichson, 1839 (Coleoptera, Staphylinidae) from the Baltic Eocene amber</strong></p>

A new species of the genus Charhyphus Sharp, 1887 (Phloeocharinae) from the Eocene Baltic amber is described and illustrated: Ch. balticus Shavrin, sp. nov. The specimen was studied by using X-ray micro-computed tomography (μCT); images of the habitus, body parts and aedeagus were obtained. Based on external morphology, the new species is related to Nearctic Ch. picipennis (LeConte, 1863) and East Palaearctic Ch. paradoxus (Bernhauer, 1933), from which it differs by the smaller body, shape of the head, and other details.