The first record of omaliine rove beetles (Coleoptera: Staphylinidae: Omaliinae) in Eocene Rovno amber

The Omaliinae, a relatively large rove beetle subfamily, contains more than 1,700 extant species in about 120 genera and 23 extinct species in 17 genera (including 10 extinct genera). Omaliinae is currently composed of seven tribes (Newton, 2022). Among the fossil omaliines, twelve species are known from amber deposits (Shavrin et al., 2025): the Baltic amber (10 species in 6 genera), mid-Cretaceous Charentese amber (one species in one extinct genus), and the Dominican amber (one species in one genus). The anthophilous Eusphalerum Kraatz, 1857 is the single genus of the tribe Eusphalerini Hatch, 1957 and contains 270 extant species, distributed in the Holarctic Region, with several species known from the northern part of the Oriental Region (Newton, 2022). The tribe Eusphalerini can be recognized from other tribes of omaliines by the presence of broadened tarsomeres 1–4 with dense and long ventral setae, the morphology of the aedeagus and female accessory sclerites, and by some other features (Zanetti, 1987, 2014). Some species have modified elytra, sometimes they are sexually dimorphic (females of some species have strongly elongate elytra, sometimes covering entire length of the abdomen); some species have modified shape of the apical abdominal tergites, etc. (e.g., Zanetti, 1987). To date, two subgenera are known in the genus (Zanetti, 2014): the nominative subgenus and Pareusphalerum Coiffait, 1959. Several groups of species were established based on a set of some external and internal morphological features (e.g., Zanetti, 1987, 2014). Adults of Eusphalerum are known as pollen-feeders and live on flowers of different plants (Klinger, 1983). Only some other taxa in Omaliini have such trophic preferences: Amphichroum Kraatz, 1857, some species of Paraphloeostiba Steel, 1960, Xanthonomus Bernhauer, 1926, etc.