Photomicrographs of Rhabdochona (Rhabdochona) acuminata (Molin, 1860) from Lake Guaíba, southern Brazil. A. Female anterior end seen with phase contrast, ventral view, showing prostom (pro), vestibule (ve) and deirids (white arrowheads). B. Female anterior end seen with phase contrast, ventral view, showing vestibule (ve), muscular esophagus (me) and nerve ring (nr). C. Female posterior region, lateral view, showing intestine (in) and anus (an). D. Eggs stained with rose bengal. Scale bars: 50 µm (A, B), 100 µm (C), 25 µm (D).