FIGURES 17–22 in Gyrosigma dongtingense sp. nov. (Bacillariophyta) from Dongting Lake, China

FIGURES 17–22. Gyrosigma dongtingense, sp. nov., SEM. 17–19. Three valve middle parts in external view showing the rotated central areas (e.g., Fig. 17, double-headed arrow), the outer proximal raphe fissures deflected in opposite directions (two arrows in Figs 17–19, respectively). 20–22. Three valve middle parts in internal view showing the two central bars (e.g., Fig. 18, two arrows), the T-shaped inner proximal endings (e.g., Fig. 19, two arrows), and the fusiform central nodule (e.g., Fig. 20, double-headed arrow). Scale bar = 1 μm (Figs 15–20).