FIGURES 17–22 in Two new species of monoraphid diatom (Bacillariophyceae) from South of China

FIGURES 17–22. Psammothidium hainanii sp. nov. Fig. 17. External view of raphe valve, scale bar = 10 μm. Fig. 18. External view of the terminal fissure, scale bar = 3 μm. Fig. 19. External view of rapheless valve, scale bar = 10 μm. Fig. 20. Internal view of the raphe valve, showed the raised helictoglossae, scale bar = 2 μm. Fig. 21. Internal view of the rapheless valve, showed the raised sternum, scale bar = 4