FIGURE 13–41 in Small diatoms (Bacillariophyta) in cultures from the Styx River, New Zealand, including descriptions of three new species

FIGURE 13–41. Planothidium spp. from the Styx River. Scales: Fig. 17, 5 µm (use for 13–20, 26–39); others 1 µm. Figs 13–25. Planothidium frequentissimum strain LCR-S:2:1:1, CHR618407. Figs 13–20, Cleaned frustules viewed by LM; Figs 13–15, araphid valve showing horseshoe structure; Figs 16–18, raphid valve (vertical pairs are through-focus images of the same frustules). Figs 19, 20, variation seen in girdle view, with convex araphid valve and concave raphid valve. Figs 21–25, SEM of cleaned frustules. Fig. 21, raphid valve; Fig. 22, araphid valve with horseshoe visible; Fig. 23, internal view of araphid valve showing structure of horseshoe; Fig. 24, internal view of half of raphid valve; Fig. 25, araphid valve with depressed pseudoraphe. Figs 26–41. Planothidium victori strain LCR-S:18:1:1, CHR618408. Figs 26–39, cleaned frustules viewed by LM; Figs 26–31, araphid valve showing horseshoe structure and curved valve margin especially in smaller valves; Figs 32–37, raphid valve (vertical pairs are through-focus images of the same frustules); Fig. 38, small araphid valve with horseshoe and hooked apex showing that the valve hook can occur at either end with respect to the horseshoe (compare with 30, 31); Fig. 39, girdle view showing convex araphid valve and concave raphid valve. Figs 40, 41, SEM of cleaned frustules. Fig. 40, araphid valve with horseshoe attachment visible; Fig. 41, oblique view of raphid valve.