Surirella wufluminensis sp. nov., internal view, SEM A–C middle details from Fig. 2D, note that fibulae extend 1/3 to 1/2 of half valve width (A), one portula between two adjacent fibulae (A, B), uniseriate striae, and valve mantle with thickened base margin (C, white arrow) D, E apical details from Fig. 2D, note two interrupted external terminal raphe endings (D, two arrows), two helictoglossa-like processes (E, two arrows) F another apex showing continuous raphe at one apex (white arrow). Scale bars: 5 μm (A); 2 μm (B–F).