FIGURES 72–77 in Ultrastructure of four Surirella taxa (Bacillariophyceae) from Qinghai Province, northwest China, with reference to the characteristics of portulae

FIGURES 72–77. Surirella lacrimula, SEM, internal view. 72–74. Three complete valves, note the slim and short fibulae, some bifurcate (one arrow respectively), and the distinct central portion (indicated by a dotted line in Fig. 74). 75. Details on the middle section from Fig. 72. Note the presence of three portulae between two adjacent fibulae (three arrows) and multiseriate striae. 76. Headpole from Fig. 72, note the continuous raphe (wave arrow). 77. Footpole from Fig. 72, note the interrupted raphe endings (two arrows). Scale bars = 5 μm (Figs 72–74), 1 μm (Figs 75–77).