Toxarium hennedyanum, all from GU44BJ-4 except C GU21AK-11, and I, K culture from GU44AK-4 A LM of valve with typical pattern in central area; 9 stria in 10 µm B SEM of a valve from same sample, 12 striae in 10 µm, with reduced central area C mucilaginous stalks with clusters of cells D internal central area, showing lack of costae E, F internal pole of valve showing asymmetrical pseudoseptum (arrow) and valve with valvocopula showing similar asymmetry (arrow) G pole of frustule in girdle view showing apical groove (arrow) on valvocopula and fimbriae partially exposed on copula H pole of frustule in girdle view showing apical notch (arrow) and the pleura (pl); note single row of areolae on mantle (*) I pole of valvocopula in girdle view, fimbriae absent from the tip J narrow portion of valve showing structure of copula (compare with Fig. 23J) and single row of pores on mantle (*) K pole of copula in girdle view showing long fimbriae. Scale bars: 50 µm (A–C); 10 µm (I); 5 µm (D–K).