FIGURES 33–39 in Bicudoa amazonica gen. nov. et sp. nov. (Bacillariophyta)-a new freshwater diatom from the Amazon basin with a complete raphe loss in the Eunotioid lineage

FIGURES 33–39. Fragilariforma species from Europe (Weierbach basin, Luxembourg, Figs 33–35) and South America (Rio Negro basin, Brazilian Amazon, Figs 36–39). Fig. 33 Valve and cingulum of F. virescens (Ralfs) D.M. Williams & Round showing marginal spines, apical pore fields, rimoportulae opening (white arrow) and connective bands with one row of areolae. Striae uniseriate composed by areolae with simple closing plates; sternum centrally located; Fig. 34 F. virescens in connective view showing mantle margin with siliceous plaques, spines present on valve face/mantle border, having spathulate tips and open girdle bands and Fig. 35 Detail of rimoportula (transapically) located on the valve pole usually aligned with the striae; Figs 36–39 Fragilariforma hamiltonii Metzeltin & Lange-Bertalot; Fig. 36 Detail of apical area showing thickened marginal spines, areola structure and absence of apical pore field; central sternum clearly visible; Fig. 37 Small specimen showing no rimoportulae aperture nor apical pore fields; Figs 38–39 Oblique internal view of F. hamiltonii showing the internal arrangement of the striae with the inner openings of areolae aligned in a narrow "ditch"; apical pore field and rimoportula absent in both species. Scale bars: Figs 33–34: 10 µm; Figs 35–37: 1 µm; Figs 38–39: 3 µm.