Unexpected palaeodiversity of omaliine rove beetles in Eocene Baltic amber (Coleoptera, Staphylinidae, Omaliinae).

Abstract

Fossil records of the subfamily Omaliinae are fragmentary and most of them are less informative compression fossils. Baltic amber from the mid-Eocene of northern Europe is one of the most important sources of insect fossils, but only two reliably placed omaliines have been described. Here, we provide a general overview of this subfamily in Baltic amber. In total, five new extinct species of four genera in three tribes are described and illustrated: Geodromicusbalticussp. nov. (Anthophagini), Eusphalerumkantisp. nov. (Eusphalerini), Paraphloeostibamorosasp. nov., Phyllodrepadaedalisp. nov., and Ph.icarisp. nov. (Omaliini). Additionally, we report on four species belonging to Eusphalerum, which remain unnamed, from the same amber deposit. The records of Eusphalerum include the first fossils of the tribe Eusphalerini, while that of Geodromicus may represent the second and the first definitive fossil record of the genus and tribe Anthophagini. Our discoveries highlight the unexpected palaeodiversity of Omaliinae in Baltic amber, further reinforcing the coexistence of thermophilous and temperate-loving beetles in Baltic amber and potentially indicating wetland and riparian habitats of amber-producing forests.