In 1844, the famous German biologist Fritz Müller published his dissertation about the leech fauna of lakes in Berlin. This study not only addressed the occurrence of leeches in the different lakes, but also contains the description of a new species - Glossiphonia verrrucata (Fr. Müller, 1844). Unfortunately, he never mentioned how many specimens he found and where he deposited the material of his dissertation research. Thus, it came as a surprise that the material appeared in the small leech collection of the Zoological Museum of the University of Greifswald. Here, we provide an overview of the material focusing especially on the four syntypes of G. verrucata. Since this is a rarely found species, we further explored historical material from the type locality, Lake Tegel, held in other museums. Our survey revealed that the material collected by Müller is the only one known to date from the species-rich Lake Tegel, which is inhabited by 14 species of freshwater leeches.