Pseudovorticella zhengae n. sp., P. difficilis (Kahl, 1933) Jankowski, 1976, and P. punctata (Dons, 1918) Warren, 1987, three marine peritrichous ciliates from north China

The morphology, infraciliature and silverline system of three marine peritrichous ciliates, Pseudovorticella zhengae n. sp., P. difficilis (Kahl, 1933) Jankowski, 1976 and P. punctata (Dons, 1918) Warren, 1987, were investigated by observation in vivo and silver-staining methods. The new species is characterized by its body shape, the appearance of the peristomial lip, the number of transverse silverlines, and the configuration of infundibular polykinety 3; P. difficilis by its body shape, the configuration of infundibular polykinety 3, and unusual annular swellings on the stalk; and P. punctata by the appearance of the pellicle, the configuration of infundibular polykinety 3, and the number of transverse silverlines.