FIGURES 56–63 in New diatom species from the Gomphonema subtile group in Southeast Asia

FIGURES 56–63: Gomphonema dalatica Glushchenko, Kulikovskiy & Kociolek sp. nov. SEM. Figs 56, 58, 60, 62 are external views; 57, 59, 61, 63 are internal views. Fig. 56. Whole valve illustrating valve shape. Fig. 57. Whole valve, showing small pseudoseptum at each pole. Fig. 58. Valve center with slightly dilated proximal raphe ends, small, round stigma opening and areolae occluded by flaps that create C-shaped openings. Fig. 59. Valve center with small central nodule bearing recurved proximal raphe ends and slit-like stigmal opening. Striae are in troughs, with thickened rims around each areola. Fig. 60. Headpole, with the hooked-shaped distal raphe end curving onto the valve mantle. C-shaped areolar openings are evident. Fig. 61. Headpole, showing prominent helictoglossa and pseudoseptum. Fig. 62. Footpole, with round porelli positioned mostly on the valve mantle, physically separated, and morphologically distinct from the areolae. Fig. 63. Footpole, with large helictoglossa and pseudoseptum evident. Porelli are occluded internally. Small siliceous projections can be seen around the areolae. Scale bars = 5 μm (Figs 56, 57); 1 μm (Figs 58–60, 62); 0.5 μm (Figs 61, 63).