Discovery of parasitengone mites (Acari) in the Gulf of Gdańsk deposits of Baltic amber ("Blue Earth" sediment) resulted in the first description of a fossil representative of Microtrombidiidae. The new species, based on larvae, displays affinity to recent members of Montenegtrombium Saboori and Pešić, 2006, Persianthrombium Sedghi, Saboori and Hakimitabar (in Sedghi et al. 2010) and Porttrombidium Haitlinger, 2000, known from the southwestern Palaearctic. A comparison with related genera and species places the newly described taxon in Porttrombidium (as Porttrombidium gedanense sp. nov.). Montenegtrombium is regarded as a junior synonym of Porttrombidium.