Transmission electron micrographs of different Klebsormidium strains. Fig. 51. Central nucleus and parietal chloroplast clearly visible. Fig. 52. Chloroplast contains pyrenoid, the outer cell wall exhibits clear layering with a corrugated outer surface, and the triangular space between the outer cell wall and the cross-wall is marked with a white arrow. Fig. 53. Pyrenoid with numerous starch grains, triangular space is marked with a white arrow. Fig. 54. Triangular space (white arrow) between the outer cell wall and the cross-wall. Fig. 55. Double-layered outer cell wall. Fig. 56. Terminal cell, showing the projections of the mother-cell wall (black arrows). Fig. 57. Two cells still not fully separated, showing the projections of the mother-cell wall (black arrows). Fig. 58. Initiating separation of two cells, the mother-cell wall is already separated (black arrows). Material illustrated is: Figs 51–54, Klebsormidium crenulatum (SAG 2415); Fig. 55, Klebsormidium dissectum (SAG 2416); Figs 56, 57, Klebsormidium nitens (SAG 2417); Fig. 58, Klebsormidium cf. nitens (STR1). Abbreviations: Chl, chloroplast; CW, cell wall; cCW, cell cross-wall; Nu, nucleus; Py, pyrenoid; V, vacuole. Scale bars Figs 51–53, 56–58, Figs 54–55: 1 µm; d, e: 500 nm.