FIGURES 102–107 in Ultrastructure of four Surirella taxa (Bacillariophyceae) from Qinghai Province, northwest China, with reference to the characteristics of portulae

FIGURES 102–107. Characteristics of the portulae among five Surirella taxa, SEM, internal view. 102, 103. Portula structure of S. liubingii, note the striated internal raphe canal wall (Fig. 102, three arrows) and the presence of only one portula between two adjacent fibulae (Fig. 103, three arrows). 104. Portula structure of S. minuta, note the occurrence of only one portula (three arrows). 105–107. Portula structure of S. lacrimula, S. brebissonii var. kuetzingii, and S. tientsinensis, respectively. Note that these three taxa have three portulae between two adjacent fibulae (three arrows respectively) but that a marginal trough-like depression is only produced in S. brebissonii var. kuetzingii (Fig. 106). Scale bars =1 μm (Figs 102–107).