Figure 1 in Helobdella stagnalis (Hirudinea: Glossiphoniidae), the first facultative mussel-associated leech in Europe

Figure 1. Map of collecting localities in the Volga and Don River basins, European Russia. The color filling indicate river basins: Don (1) and Volga (2). The red circles indicate localities in which freshwater mussels (Unionidae) were infested by the glossiphoniid leech species Helobdella stagnalis. The green circles indicate localities in which freshwater mussels were not infested by leeches. The yellow circles indicate the larger cities. The raw data on occurrence of leech and mussel host can be downloaded from figshare (Bolotov et al. 2022: Dataset 1).