Surirella wufluminensis sp. nov., external view, SEM A a whole valve B middle detail from A showing the shallow depressions on the valve face correspond to the ones on the mantle (four arrows) C–E details from Fig. B showing mound-like siliceous outgrowths on the valve surface (C, D, three wavy arrows respectively), raised longitudinal ridges on both sides of the raphe (C, two arrows), slit-like external openings of areolae on both valve face and mantle (D–F) F, G apical details from A, note interrupted terminal raphe endings (see also Fig. 4D). Scale bars: 20 μm (A); 3 μm (B, C, F, G); 1 μm (D, E).