Staurosirella crux (Ehrenb.) Van de Vijver & Kusber comb. nov., LM and SEM micrographs taken from the original Smith type material for Odontidium harrisonii (BR-4685, Hull, United Kingdom). A. LM picture of a frustule in girdle view. B–M. LM pictures of valves in valve face view in decreasing length. N. SEM external view of a complete valve. O. SEM external detail of the footpole showing the large apical pore field. P. SEM external detail of part of the central area with the marginal spines, the large virgae and the vimines. Q. SEM internal view of a complete valve. Scale bar = 10 µm (A–N, Q), 1 µm (O–P).