These flatworms were uninvited guests in a freshwater aquarium tank of the Haus des Meeres (Aqua Terra Zoo) in Vienna, Austria. The tank is thematic and called "Matano See". Matano lake is a lake in Indonesia, it's possible that the flatworms came from here but more probably they just appeared from elsewhere.According to planarian expert Sumie-dh (
mstdn.science/@sumie_dh ) these belongs to genus Girardia with three probable species:Girardia tigrina, Girardia dorotocephala and Girardia sinensis.His reply is that:"Hard to say which one without genetics, histology will not work there since those aquarium strains are fissiparous. It can be G. tigrina, perhaps dorotocephala or sinensis, all 3 species are now invasive in various corners of Europe"
