Hannaea inaequidentata, an initial frustule, external view, SEM 85 complete initial frustule, note its rounded, cylinder-like, twisted outline 86 middle detail of Fig. 85, showing central area, sternum not developed (two arrows), longitudinal perizonium wholly covering valve surface, no transverse perizonium bands 87 detail of Fig. 85 showing longitudinal perizonium (arrows), plaques (arrowheads), and two girdle bands 88 detail of Fig. 86 showing longitudinal perizonium (arrows) 89 apex detail of Fig. 85 showing longitudinal perizonium (arrow) and irregular ocellulimbus located in valve margin (curved arrow) 90 another apex of Fig. 85, note depressed pole (arrow). Scale bars: 20 μm (85), 10 μm (52), 1 μm (86–90).