FIGURES 15–18 in Valve Morphology and Ultrastructure of the Enigmatic Diatom Cymbopleura semirecta (Manguin ex Kociolek & Reviers) Bahls

FIGURES 15–18. External ultrastructure of Cymbopleura semirecta (Manguin ex Kociolek & Reviers) Bahls. Fig. 15: Entire valve, showing undulate raphe branches. Fig. 16: Central area showing uniseriate, radiate striae and expanded external proximal raphe ends. Figs 17-18: External apices showing dorsally hooked distal raphe fissures and indicating a lack of apical pore fields. Scale: fig. 15 = 40 µm, fig. 16 = 10 µm, fig. 17 = 5 µm, fig. 18 = 5 µm