First Records of Beetle Fauna (Insecta: Coleoptera) from Late Glacial Sediments of Lithuania: Novel Environmental Reconstructions

This study presents the first subfossil beetle (Coleoptera) records from Lithuania, from Late Glacial organic deposits. Bulk sediment samples were collected from the Pamerkiai and Zervynos Outcrops in SE Lithuania, and from the Ventė Outcrop at the eastern coast of the Curonian Lagoon, W Lithuania. Radiocarbon dating determined that the studied sediments accumulated between ~15,000–11,300 cal BP. The beetle assemblages (29–177 individuals per sample) consist of many cold-adapted species that are common from Late Glacial deposits in the British Isles, Southern Sweden, and continental Europe. True arctic species are absent from the assemblages, and it is likely that the Lithuanian beetle fauna was most similar to nearby southern regions (e.g., Poland) during the Late Glacial. Besides a variety of aquatic species and typical wetland species, many beetle species living in open environments and on sandy soils were identified. In almost all the samples, taxa associated with pine trees, willows, and birches were found, confirming previous reconstructions of a sparsely forested landscape during the climatic periods GI-1e–GI-1a (Bølling-Allerød). The species assemblages from the youngest samples, associated with GS-1 (Younger Dryas), indicate the disappearance of large aquatic macrophytes and decreasing temperatures in Southern Lithuania, but a persistence of trees in the region.