Wheeler’s dilemma revisited: first Oecophylla–Lasius syninclusion and other ants syninclusions in the Bitterfeld amber (late Eocene)

Abstract

The first syninclusions of extant tropical and Holarctic ant genera are reported from Bitterfeld amber: the tropical Oecophylla F. Smith (O. brischkei Mayr, 1868) with the Holarctic genus Lasius F. (four workers of L. schiefferdeckeri Mayr, 1868), and others. The ratio of tropical and Holarctic ants in Bitterfeld, Baltic, Rovno and Danish ambers is analyzed; Holarctic ants dominate in all ambers, consistent with late Eocene climate. Oecophylla, Lasius and the temperate extant Palaearctic caddisfly genus Beraeodes Eaton are dominant as compression fossils in the terminal Eocene Bembridge Marls, UK. Syninclusions of Oecophylla with Lasius, as well as syninclusions of Beraeodes with Yantaromyrmex Dlussky et Dubovikoff, 2013 in Rovno amber, are consistent with an equable climate of the late Eocene amber forests of Europe. The cooccurrence of Oecophylla, Lasius and Beraeodes at the terminal Eocene in the Bembridge Marls supports a late Eocene age of European ambers. The coexistence of Oecophylla and Lasius in Europe was possible only from the late Eocene to the late Miocene: until the late Eocene, the climate in European middle latitudes was too hot for aphids, the obligate symbionts of Lasius, but after the late Miocene it became too cold for Oecophylla. The dominance of Oecophylla in the periodically flooded terminal Eocene Bembridge environment might be explained by its arboreal lifestyle providing a competitive advantage over terrestrial Formica species, for which nesting places were quite limited under these conditions. How to cite this article: Radchenko A.G., Perkovsky E.E. 2021. Wheeler's dilemma revisited: first Oecophylla-Lasius syninclusion and other ants syninclusions in the Bitterfeld amber (late Eocene) // Invert.

A new genus of the subfamily Languriinae (Coleoptera: Erotylidae) from the Late Eocene Baltic amber

“…Thus, our new finding does not affect the overall picture of the high abundance of tropical elements in the Bitterfeld and Rovno amber forests versus Baltic amber forest as predicted by Wolfe et al (2016) and Mänd et al (2018), and supported faunistically not only by assessment of the amber faunas of ants, bethylids and biting midges (Perkovsky, 2016(Perkovsky, , 2017(Perkovsky, , 2018Radchenko & Perkovsky, 2021;Colombo et al, 2021с), but also newly unveiled, abundant Rovno amber records of the thermophile beetles, hymenopterans and termites (Legalov et al, 2018;Perkovsky et al, 2020;Sokolov & Perkovsky, 2020;Colombo et al, 2021 a, b;Perkovsky & Nel, 2021;Matalin et al, 2021, Yamamoto et al, 2022.…”

Sociality, Communities and Morphological Features of Ants From Mid-Cretaceous Burmese Amber

“…Apparently, protection of food sources exhibits at the level of certain individuals. Indeed, the syninclusions of two ants badly injured in the fight reveal us that the struggle lasted for quite a long time, even so these ants remained one on one, while modern ants in such situations most commonly have the assistance, that was also reflected in the Eocene amber (for example, Radchenko and Perkovsky, 2021). Obviously primitive polymorphism based on isometric size variation of workers could also be observed among stem ant taxa (Cao et al, 2020b).…”

CeutorhynchusGermar (Coleoptera, Curculionidae) as proxy for Eocene core Brassicaceae: first record of the genus from Rovno amber

“…Of the 21 extant species of the inaffectatus -group with known hosts (Colonnelli, 2004), 19 are from forest, segetal, or ruderal hosts (Ignatov, personal communication, 2021). We therefore presume that they and their associated insects likely were less affected by the Eocene/Oligocene climatic and biotic turnover (Radchenko and Perkovsky, 2021).…”