FIGURES 13–20. Cocconeis sawensis from Brazil. Raphe valves. 13–18. SEM. 19, 20. TEM. 13, 15 in Additional morphological features of the epiphytic diatom Cocconeis sawensis Al-Handal & Riaux-Gobin (Cocconeidaceae, Bacillariophyta) from a coastal lagoon, Southern Brazil

FIGURES 13–20. Cocconeis sawensis from Brazil. Raphe valves. 13–18. SEM. 19, 20. TEM. 13, 15. External view of the valve. 14. Internal view of the valve showing an irregular and raised marginal rim. 16, 17. Detail of the internal valves ends. Note raphe lying in a very narrow raised axial area and distal raphe ending a small helictoglossae. 18. Detail of the central area round and slightly raised with raphe endings deflected in opposite directions. 19. Valve. 20. Detail of hymenes occluding areolae with radial perforations. Scale bars = 200 nm (Fig. 20), 1 μm (Figs 16–18), 2 μm (Figs 13, 14, 15, 19).