The water bodies formed in forest complexes are characterised by a significant degree of isolation from other aquatic environments as well as from urban agglomerations. In industrial areas, they are refuges of biological diversity. The long-term ecological research carried out in woodland ponds has allowed us to identify a new site of the occurrence of Placobdella costata (F. Müller) (Hirudinida: Glossiphoniidae) in Poland, the fourth in the southern part of the country. Furthermore, ecological information about the habitat and accompanying freshwater leeches are given.