FIGURES 33–38 in Four new Pinnularia Ehrenberg (Bacillariophyta, Pinnulariaceae) species from Amazonian black water (Tupé Lake, Amazonas State, Brazil)

FIGURES 33–38. SEM: Pinnularia walkerae sp. nov. External view of morphological features. Fig. 33. General view of valve. Fig. 34. Detail of central area showing proximal raphe fissures bent in same direction. Figs 35, 36. Detail of alveolus showing 3–7 rows of areolae. Figs 37, 38. Detail of pole with sickle-shaped raphe and showing alveoli structure. Scale bars: Fig. 33 = 10 µm; Figs 34, 37 = 5 µm; Fig. 35 = 2 µm; Figs. 36, 38 = 1 µm.