FIGURES 20–23 in Three new species of Ulnaria (Bacillariophyta) from the Wuling Mountains Area, China

FIGURES 20–23. Ulnaria sinensis sp. nov., SEM. 20. One pole of two valves showing the basal siliceous layer, note the tiny poroids located at the end of the striae on the mantles (arrows). 21–22. Two poles in girdle view showing the closed valvocopulae, note the spatulate linking spines and the tiny poroids located at the end of the striae on the mantles (arrows). 23. Part of one girdle band, note the closed nature and one row of pores locating in the middle. Scale bars = 5 μm.