A–F SEM images of Pseudostaurosira aedes sp. nov. from the Bolivian Altiplano A top, tilted view of valve showing axial area, slightly raised virga, valve face areolae covered with bilobed or disk-like flaps, and slightly larger valve mantle areola covered with two or more flaps B, D, E, F girdle views showing features of the valve mantle, open girdle elements with larger valvocopula (white arrows in D and E). Notice serrate spines with well-developed stipules in F which have varying patterns C inner view showing reduced apical pore field (black arrow) and single depression into which the areolae open internally (dotted arrow). Scale bars: 4 µm (D); 5 µm (A–C, E, F).