New and Interesting Diatoms from the Shiwan Wetwalls, Yunnan Province, China. III. Valve ultrastructure of four new species of Eunotia (Bacillariophyceae: Eunotiales)

Four new Eunotia (Bacillariophyceae: Eunotiales) species are described from the Shiwan Wetwalls in Yunnan Province, China, based on light and scanning electron microscopy. The four species all share the features that assign them to the genus, including asymmetry about the apical axis, raphe predominantly on the valve mantle, and presence of one or more rimoportulae, and they all possess pseudosepta. They differ from one another in several attributes, however. Three of the species possess striae contained in internal troughs, two have spines (either one stout spine at each apex or blunt spines along the dorsal margin) and one has thickened ridges between the striae. These observations of four new Eunotia species further demonstrates the diversity and uniqueness of this wetwall community in Yunnan.