Białowieża Primeval Forest, a lowland semiboreal forest complex at the Polish-Belarussian border, is the second region in Poland, besides Pomerania, where Rhamphomyia marginata (Fabr.) has been recorded since at least 100 years. Abundant occurrence of this very distinctive dance-fly in boreo-continental habitats suggests that its geographic distribution extends further eastward than previously believed, e. g. through Belarussia and Lithuania.