FIGURES 17–23 in Two new species of Plagiostriata (Bacillariophyaceae) from sand sediments of southern China

FIGURES 17–23. Plagiostriata pingtanensis sp. nov. from type material, SEM. 17. External view of the valve with a rimoportula (arrow). 18. Central area of a valve with a rimoportula. 19. External views of the valve with no rimoportula. 20. Internal views of the valve with no rimoportula. 21. Internal views of the valve with a rimoportula (arrow). 22. Girdle view of P. pingtanensis sp. nov., composed of three bands. 23. Apical fields of the internal valve. Scale bars = 1 μm (Figs. 17, 19–21, 23), 0.5 μm (Figs. 18, 23).