Staurosirella marginostriata Van de Vijver & V.Peeters, sp. nov., LM and SEM micrographs taken from the holotype material (BR-4840, Bosbeek, Maaseik, Belgium) A LM picture of a frustule in girdle view B–R LM pictures of valves in valve face view in decreasing length S SEM external view of a complete valve in oblique view showing the girdle structure and the mantle T SEM external view of a complete frustule with focus on the apical pore field and the transition between valve face and mantle U SEM external view of a complete valve. Note the undulating valve face surface and the small mantle plaques (see arrows) V SEM external view of a complete smaller valve with flattened valve face surface. The arrows indicate mantle plaques W SEM external detail of a valve apex showing the large apical pore field X SEM internal view of a complete valve. Scale bars: 10 µm (A–V, X); 1 µm (W).