Paradiplozoon yunnanensis n. sp. (Monogenea, Diplozoidae) from Sikukia gudgeri (Cyprinidae, Barbinae) in southwest China.

Paradiplozoon yunnanensis n. sp. (Monogenea, Diplozoidae) is described from the gills of Sikukia gudgeri Smith, 1931 (Cyprinidae) collected from Jinghong Basin, a tributary of the international Lancang-Mekong River. This is the first diplozoid species from S. gudgeri and its description increases the number of Paradiplozoon species recorded in China to 25. The new species is distinguished from congeners by a combination of morphological and molecular features. The anterior end of the median plate is thickened in the marginal area and a narrow rectangular trapeze spur connects to the anterior jaw through two separate anterior joining sclerites. The posterior end of the median plate sclerite is invaginated with a smooth strip-shaped posterior joining sclerite. Comparison of a newly obtained sequence of rRNA ITS2 with 18 other congeneric sequences from GenBank provides support for separation of the new species.