FIGURES 90–95 in Ultrastructure of four Surirella taxa (Bacillariophyceae) from Qinghai Province, northwest China, with reference to the characteristics of portulae

FIGURES 90–95. Surirella brebissonii var. kuetzingii, SEM, external view. 90, 91. Two complete valves, note the valve composed of a central portion and outside portion (indicated in Fig. 91). 92. Details of the middle section from Fig. 90, note costa-stria bundles (CSBs) alternating with over-fibula costae (OFCs). 93, 94. Details of the headpole (Fig. 93) and footpole (Fig. 94) from Fig. 90. Note the simple, interrupted raphe endings at both poles (two arrows respectively). Scale bars = 5 μm (Figs 90, 91), 1 μm (Figs 92–95).