FIGURES 15–24 in New species and a new genus of the Orthoseirales from Patagonia, Argentina, with comments on systematic affinities within the Order

FIGURES 15–24. "Cyclotella stipata Frenguelli" from Tierra del Fuego (Figs 15, 18, 20, 22) and Limay River basin (Figs 16–17, 19, 21, 23–24). 15–17. LM. Valve views. 18–23. SEM. 18–20. External valve views. 18–19. Whole valves, note marginal spines and spinules lined up with the striae. 20. Detail of central hyaline area showing external openings of carinoportulae (arrow) and rimoportulae (arrowhead). 21–24. Internal valve views. 21. Whole valve. 22–23. Details of valve center, note the internal openings of carinoportulae (arrow) and rimoportulae (arrowhead). 24. Detail of striae arrangement. Scale bars = 10 μm (Figs 15–18, 21), 5 μm (Figs 19, 24), 2 μm (Figs 20, 22–23).