Photomicrographs of Mononchus truncatus Bastian, 1865. Females from populations collected from riverbanks of the rivers Rezovska (A, D, F, G, H, K), Danube (B, E, J, L) and Shirokoleshka (C, I, M, N): A body, total view B–F anterior region (ventro-sublateral ribs arrowed in D; amphid opening arrowed in E; transverse ridge arrowed in F) G, H, L vulval region: G vulval opening, ventral view H vulva and part of posterior genital branch (posterior uterus and part of pars dilatata oviductus), lateral view L vulval region showing pars refringens vaginae I–K tail M, N tail tip showing papilla (arrowed in M) and terminal spinneret (N). Scale bars: 400 µm (A); 20 µm (B–H, L–N); 50 µm (I–K).