Fig. 1

Sampling sites of individuals of Isthmiophora melis in Poland. Study sites are marked with dots: WMNP—Warta Mouth National Park; DNP—Drawa National Park; SNP—Słowiński National Park; BNP—Biebrza National Park; NNP—Narew National Park; VR—Vistula River; RMP—Milicz Ponds Nature Reserve (the map was created using SimpleMappr—https://www.simplemappr.net)