FIGURES 26–33 in New diatom species from the Gomphonema subtile group in Southeast Asia

FIGURES 26–33: Gomphonema pantropicum Reichardt. SEM. Figs 26, 28, 30, 32 are external views; 27, 29, 31, 33 are internal views. Fig. 26. Whole valve illustrating valve shape, with characteristic headpole and footpole. Fig. 27. Whole valve, showing small pseudoseptum at each pole, and prominent central nodule. Fig. 28. Valve center with slightly dilated proximal raphe ends, small, round stigma opening and areolae occluded by flaps. Fig. 29. Valve center with undulate central nodule bearing bent proximal raphe ends and ovoid stigma opening. The striae occur in trough-like structures. Fig. 30. Headpole, with the hooked-shaped distal raphe end curving onto the valve mantle. Occluded areolae are evident. Fig. 31. Headpole, showing prominent helictoglossa and pseudoseptum. Fig. 32. Footpole, with round porelli physically separated and morphologically distinct from the areolae. Fig. 33. Footpole, with large helictoglossa and pseudoseptum evident. Scale bars = 5 μm (Figs 26, 27); 1 μm (Figs 28–33).