New material of Euroleptochromus tuberculatus Yin & Cai (Coleoptera: Staphylinidae: Scydmaeninae) in Eocene Baltic amber

The extinct members of the ant-like stone beetle supertribe Mastigitae are among the best studied groups of all fossil Scydmaeninae, and their evolutionary history can be traced from the latest Albian to the earliest Cenomanian through Miocene/Oligocene, with seven extinct genera being described (summarized in Jaloszynski, 2016; Jaloszynski & Perkovsky, 2016; Jaloszynski et al., 2018; Ross, 2019-2022 (list of Burmese amber taxa)). The genus Euroleptochromus Jaloszynski, placed as a sister group to the modern Leptochromus Motschulsky, comprises three species from the mid-late Eocene Baltic amber (Jaloszynski, 2012; Jaloszynski et al., 2018; Yin & Cai, 2018). Two of these species, E. sabathi Jaloszynski and E. setifer Jaloszynski & Brunke, have the postgenae with two long apical bristles derived from an extended, elongate projection, while the third species, E. tuberculatus Yin & Cai, lacks such a projection on postgenae, demonstrating a notable variability of genal structures within the genus. Only a single specimen of Euroleptochromus tuberculatus has been known; and most ventral structures of this specimen are obscured by a ' milky ' film that prevents a detailed interpretation of their morphology. Here we report the discovery of a second, better preserved specimen and supply some morphological details of E. tuberculatus.