FIGURES 51–58 in Transfer of Fragilaria atomus Hust. to the genus Stauroforma (Bacillariophyta) based on observation of type and newly collected material

FIGURES 51–58. SEM: Stauroforma atomus comb. nov. BRM E2963 (lectotype). Figs 51–56. External view of valve showing headpole (white arrow) and foot-pole (black arrow). Fig. 56. Detail of curved striae with different sizes at head-pole (arrow). Fig. 57. Detail of foot-pole with the poroids of the apical pore field (arrow) and areolae containing a slightly branched structure. Fig. 58. Internal view of valve showing two poroids at foot-pole (arrow). Scale bars = 1.5 µm (Figs 51, 53–54), 1 µm (Figs 52, 55–56, 58), 500 nm (Fig. 57).