Based on representative collections, the ratio of tropical and Holarctic ant species in Priabonian (Late Eocene) Baltic, Bitterfeld (Saxonian), Danish and Rovno ambers is analyzed for the first time. In surveyed representative collections of Baltic amber, the ratios of Holarctic and tropical ant species are from 1.1 to 1.5; with 10 Holarctic and 9 tropical species (out of 31) in the PIN-964 collection, and 9 and 5 species (out of 29) in the Giecewicz collection; the ratio in the representative collection of Saxonian amber is 0.9, 11 Holarctic species vs. 12 tropical species (out of 55); in the representative collection of Rovno amber it is 0.65, 15 vs. 23 species (out of 79); and in the representative collection of Danish amber it is 0.64, 7 vs. 11 species (out of 36). Hence, in representative collections of Baltic amber, Holarctic species clearly prevail not just in terms of the share of their specimens (by 9.8 to 19.6 times), but also by the number of species. In Bitterfeld amber, Holarctic species are somewhat less numerous than tropical ones, but their specimens are 6 times greater. In representative collections of Rovno and Danish ambers, the number of Holarctic species is 1.5 to 1.7 times smaller than that of tropical species, but the number of their specimens is 4.9 to 6.9 times greater. The numbers of tropical and Holarctic species represented by more than one specimen is similar in Priabonian ambers, 25 versus 22, but Holarctic species include four dominants or subdominants. The abundance of temperate elements in the Priabonian amber ant fauna along with the relatively small number of tropical elements greatly distinguishes it from the Middle European Lutetian ant faunas of Messel and Eckfeld in shale, which do not have temperate elements at all. Formica phaethusa Wheeler, Glaphyromyrmex oligocenicus Wheeler, Plagiolepis squamifera Mayr, Proceratium eocenicum Dlussky, Hypoponera atavia (Mayr), Ponera lobulifera Dlussky, Aphaenogaster mersa Wheeler, and Ennaemerus reticulatus Mayr are new records for Rovno amber, and Formica gustawi Dlussky and Gnamptogenys europaea (Mayr) for Danish amber.

The composition of syninclusions was analyzed in three representative samples of the Late Eocene Rovno amber. Statistical analysis revealed a stable connection between three pairs of taxa in all three samples, viz., the midges Chironomidae and Ceratopogonidae; the flies Dolichopodidae and aphids Germaraphis; and the mite Glaesacarus rhombeus and Sciara zone dipterans (Sciaroidea, Tipuloidea, etc.). The first pair is interpreted as representing the assemblage of aeroplankton insects; the second, the assemblage of dwellers of the trunks of amber trees; and the third pair, the assemblage of dead wood consumers. The results, although provisional, support the idea that the study of syninclusions is a useful instrument for understanding the structure of past communities.

Four Middle Eocene orthoclad species,Heterotrissocladius naibuchisp. n.,Paraphaenocladius nadezhdaesp. n.,Pseudosmittia kodrulaesp. n. andSmittia sukachevaesp. n.. are described and figured. Based on the combination of the diptera fauna composition and paleobotanical data, suggestions on the climate and habitats of the Sakhalin amber forest are given.

Three species of chrysidoid wasps, Palaeobethylus longicollis (Chrysididae), Dryinus wunderlichi and D. reifi (Dryinidae) are recorded for the first time for Rovno amber from the basin of Styr River (Voronki), and one species, Palaeoanteon janzeni (Dryinidae), is recorded for the first time for Rovno amber from the basin of Stokhod River (Kukhotskaya Volya). Taking into account the new records of chrysidoid wasps and myrmiciine ants, a total of 64 species of Rovno hymenopterans (52%) are registered at Baltic amber. All known fossil records of the wasps in the superfamily Chrysidoidea are listed.

The subfamily Epyrinae is the most common in the bethylid fossil record. Its geological history ranges from the Eocene to the Pleistocene, and it is the only subfamily that has no records in the Cretaceous. Here we revise, diagnose and illustrate known epyrine fossil wasps. A new genus is proposed, †Gloxinius Colombo & Azevedo gen. nov., to contain the species †Gloxinius bifossatus (Brues, 1939 Brues, C. T. 1939. New Oligocene Braconidae and Bethylidae from Baltic amber. Annals of the Entomological Society of America, 31, 251–263. doi:10.1093/aesa/32.2.251 [Crossref] , [Google Scholar] ) comb. nov., transferred from Epyris Westwood, 1832 Westwood, J. O. 1832. Descriptions of several new British forms amongst the parasitic hymenopterous insects. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1, 127–129. doi:10.1080/14786443208647849 [Taylor & Francis Online] , [Google Scholar] . The species †Chlorepyris concaptus (Brues, 1933 Brues, C. T. 1933. The parasitic Hymenoptera of the Baltic amber. Part I. Bernstein-Forschungen, 3, 4–172. [Google Scholar] ) comb. nov., †Chlorepyris invelatus (Brues, 1933 Brues, C. T. 1933. The parasitic Hymenoptera of the Baltic amber. Part I. Bernstein-Forschungen, 3, 4–172. [Google Scholar] ) comb. nov. and †Chlorepyris setosus (Brues, 1933 Brues, C. T. 1933. The parasitic Hymenoptera of the Baltic amber. Part I. Bernstein-Forschungen, 3, 4–172. [Google Scholar] ) comb. nov. are transferred from Epyris Westwood, 1832 Westwood, J. O. 1832. Descriptions of several new British forms amongst the parasitic hymenopterous insects. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1, 127–129. doi:10.1080/14786443208647849 [Taylor & Francis Online] , [Google Scholar] to Chlorepyris Kieffer, 1913a Kieffer, J. J. 1913a. Nouveaux microhyménoptères de l'Afrique équatoriale. Bollettino del Laboratorio di Zoologia Generale e Agraria della R. Scuola Superiore d'Agricultura, 7, 105–112. doi:10.5281/zenodo.23805 [Crossref] , [Google Scholar] . Three species are transferred from Epyris Westwood, 1832 Westwood, J. O. 1832. Descriptions of several new British forms amongst the parasitic hymenopterous insects. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1, 127–129. doi:10.1080/14786443208647849 [Taylor & Francis Online] , [Google Scholar] to Pristocerinae: †Merascylla Colombo & Azevedo gen. nov. is proposed to contain †Merascylla atavella (Cockerell, 1920 Cockerell, T. D. A. 1920. Fossil arthropods in the British Museum, I. Annals and Magazine of Natural History, 5, 273–279. doi:10.1080/00222932008632376 [Taylor & Francis Online] , [Google Scholar] ) comb. nov., and †Pseudisobrachium elatus (Brues, 1933 Brues, C. T. 1933. The parasitic Hymenoptera of the Baltic amber. Part I. Bernstein-Forschungen, 3, 4–172. [Google Scholar] ) comb. nov. and †Pseudisobrachium inhabilis (Brues, 1923 Brues, C. T. 1923. Some new fossil parasitic Hymenoptera from Baltic amber. Proceedings of the American Academy of Arts and Sciences, 58, 327–346. doi:10.2307/20025999 [Crossref] , [Google Scholar] ) comb. nov. are transferred to Pseudisobrachium Kieffer, 1904a Kieffer, J. J. 1904a. Descriptions de nouveaux Dryinidae et Bethylidae du Musée Civique de Gênes. Annali del Museo Civico di Storia Naturale di genova, 41, 351–412. [Google Scholar] . One species is transferred from Epyris Westwood, 1832 Westwood, J. O. 1832. Descriptions of several new British forms amongst the parasitic hymenopterous insects. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1, 127–129. doi:10.1080/14786443208647849 [Taylor & Francis Online] , [Google Scholar] to Scleroderminae: †Mael Colombo & Azevedo gen. nov. is proposed to contain †Mael longiceps (Brues, 1923 Brues, C. T. 1923. Some new fossil parasitic Hymenoptera from Baltic amber. Proceedings of the American Academy of Arts and Sciences, 58, 327–346. doi:10.2307/20025999 [Crossref] , [Google Scholar] ) comb. nov. Ten new species are described from Baltic and Rovno ambers: †Chlorepyris deploegi Colombo & Azevedo sp. nov., †Chlorepyris engeli Colombo & Azevedo sp. nov., †Chlorepyris hopei Colombo & Azevedo sp. nov., †Chlorepyris jouaulti Colombo & Azevedo sp. nov., †Chlorepyris mckellari Colombo & Azevedo sp. nov., †Chlorepyris meunieri Colombo & Azevedo sp. nov., †Chlorepyris neli Colombo & Azevedo sp. nov., †Chlorepyris perrichoti Colombo & Azevedo sp. nov., †Holepyris rasnitsyni Colombo & Azevedo sp. nov. and †Holepyris terayamai Colombo & Azevedo sp. nov. The species †Laelius nudipennis Brues, 1933 Brues, C. T. 1933. The parasitic Hymenoptera of the Baltic amber. Part I. Bernstein-Forschungen, 3, 4–172. [Google Scholar] is no longer classified as Bethylidae and it is transferred to Platygastroidea incertae sedis. Eighty-one fossil species are now recognized in Bethylidae, with 30 belonging to Epyrinae and distributed within six genera. A key for fossil epyrines is provided. http://zoobank.org/urn:lsid:zoobank:org:pub:A7481392-3BD2-45F3-A035-34E515A34218