FIGURES 256–261. SEM. 256–261. Gomphonema acuminatum. External views. 256 in The diatom genus Gomphonema Ehrenberg in Lake Baikal. II. Revision of taxa from Gomphonema acuminatum and Gomphonema truncatum-capitatum complexes

FIGURES 256–261. SEM. 256–261. Gomphonema acuminatum. External views. 256. External view of central area to headpole. Proximal and distal ends evident. 266. Central area with dilated proximal raphe ends and small, round stigma opening evident. 258. Headpole showing protracted apex and hooked distal raphe end. 259. Footpole with deflected distal raphe end bisecting apical pore field on the valve mantle. 260, 261. Gomphonema pseudacuminatum sp. nov., external views. 260. Entire valve view showing valve proportions. 261. Central area with dilated proximal raphe ends, small elliptical stigma opening and occlusion of areolae resulting in C-shaped openings. Scale bars = 5 μm in Figs 256, 260, 2 μm in Fig. 258, 1 μm in Figs 257, 259, 261.