Redescription of Protoopalina pingi Nie, 1935 inhabiting the recta of Hylarana guentheri and Pelophylax nigromaculatus in China.

A redescription of Protoopalina pingi Nie, 1935 is presented in this paper to complete Nie's description at both light and scanning electron microscope levels. These organisms were collected from the recta of the frogs Hylarana guentheri Boulenger, 1882 and Pelophylax nigromaculatus Hallowell, 1861 from Jialing River, Sichuan Province and Honghu Lake, Hubei Province, respectively, in China. This is the first record of its occurrence in H. guentheri and P. nigromaculatus. The body of P. pingi is elongated and somewhat spindle-like in shape, slightly narrowed and bluntly rounded at the anterior extremity, while the posterior end is tapering or sharply pointed. The body surface is thickly flagellated, with the caudal tip being barren. The falx, located at the margin of the anterior end, is composed of a narrow band of kinetosomes. Four round or oval-shaped nuclei, usually arranged in a straight line, are situated in the middle region of the body. Comparisons are made between P. pingi and its congeners.