FIGURES 19–25 in Rhoicosphenia johannessoniae (Bacillariophyceae), a new diatom from the Swedish coast of the Baltic Sea

FIGURES 19–25. SEM images of the D-valve of Rhoicosphenia johannessoniae sp. nov. Fig. 19. Internal side with pseudoseptae on the poles, note the bluntly rounded base valve apex, Fig. 20. External side showing reduced raphe branches, Fig. 21. Girdle view of the valve with a cingular band attached, Fig. 22. External side of the head pole showing slit-like areolae, Fig. 23. External side of the base pole with the reduced raphe branch and pore field, Fig. 24. External side of the head pole with very short raphe branch and slit-like areolae, Fig. 25. Internal side of the base pole with pseudoseptum and raphe branch. Scale bars 5 μm (Figs 52–54), 1 μm (Figs 55–58).