Staurosirella vanheurckiana Van de Vijver, Ballings & M.de Haan, sp. nov., LM and SEM micrographs taken from the holotype material (BR-4844, Van Heurck Types du Synopsis 315, Leuven, Belgium) A, B LM pictures of a frustule in girdle view C–AE LM pictures of valves in valve face view in decreasing length AF SEM external view of a complete (slightly eroded) frustule in oblique view showing the girdle structure and the mantle AG–AI SEM external view of a three complete heteropolar valves with focus on the apical pore field. Note the depressed headpole in AI AJ SEM external detail of a valve apex showing the large apical pore field AK–AL SEM internal view of two complete valve. Scale bars: 10 µm (A–AG, AK); 1 µm (AH–AJ, AL).