FIGURES 17–22 in Two new Nitzschia species (Bacillariophyceae) from China, possessing a canal-raphe-conopeum system

FIGURES 17–22. Nitzschia arierae, sp. nov., canal-raphe-conopeum system, SEM. 17. External view of the apex, note that the conopea are fused into the valve (arrow). 18–19. External view of central area, note conopeal canal, raphe canal and supporting points. 20–22. Internal views, note keels and supporting marks. Abbreviations: c = conopeum, cc = conopeal canal, cv = zone of valve face subtended by conopeum, f = fibula, k = keel, r = raphe slit, rc = raphe canal, sm = supporting mark, v = uncovered zone of valve face. Scale bars = 1 μm (Figs 17–18, 20–22), 2 μm (Fig. 19).