FIGURES 21–26 in Navicula gogorevii-a new, large-celled diatom species from Vietnam (Southeast Asia)

FIGURES 21–26: Navicula gogorevii Chudaev, Glushchenko, Kulikovskiy & Kociolek, sp. nov. SEM. Internal view. Figs 21, 22: Whole valve. Figs 23, 24: Central area. White arrows show the raphe slits open obliquely to the secondary valve side. Proximal raphe endings straight, positioned on the slight widening of raphe-ridge, with short intermissio. Black arrows show the prominent accessory rib, unilaterally widened to the primary valve side. Black arrowhead shows the shallow longitudinal furrow. White arrowhead shows the extended accessory rib. Figs 25, 26: Valve ends. Black arrows show the helictoglossae. White arrow shows the raphe slit open obliquely to the secondary valve side. White arrowheads show the cushion-like thickenings at the ends of accessory rib. Black arrowheads show the apically-elongated openings of apical areolae. Scale bars = 10 μm (Figs 21, 22); 2 μm (Figs 23, 24); 1 μm (Figs 25, 26).