A new extinct monotypic genus and species of the cylindrical bark beetles, Semicoxelus sontagae gen. et sp. nov., is described and figured based on an inclusion in Baltic amber. The new representative from the Eocene is classified within the synchitine tribe and placed near the morphologically close extant genera, including Coxelus Dejean, Diodesma Latreille and Notocoxelus Ślipiński & Lawrence. The description and comparison of the new fossil are accompanied by a brief discussion focusing on an interesting morphological character of cylindrical bark beetles: the presence/absence of interfacetal setae on the eyes.