FIGURES 19–32 in Lectotypification, emended description and distribution of Planothidium distinctum (Achnanthidiaceae, Bacillariophyceae)

FIGURES 19–32: Planothidium distinctum LM and SEM images of specimens from Lake Lia lacustrine sediment. Figs 19– 20. LM of rapheless valves. Figs 21–28. LM of raphid valves. Fig. 29. External view of raphid valve. Note straight, simple raphe endings. Fig. 30. Internal view of raphe valve, note central raphe endings deflected in opposite directions. Fig. 31. Whole frustule, external view of rapheless valve. Valve and mantle, latter bears row of poroids with number exactly 3 x that of striae. Fig. 32. Internal view of rapheless valve. Scale bars = 10 µm for figs 19–28, 5 µm for figs 29–32.