A–F SEM micrographs, the valvocopula of C. crisscrossis sp. nov. from Qingyi River with well-developed digitate fimbriae, which is close and heavily silicified clamp-like fimbriae seem to be attached to the hyaline rim and are irregularly spaced; the poles of valvocopulae possess unique ‘sword-shaped’ siliceous extensions (arrows in A–F) A valvocopula of the RV B–F valvocopula of the SV. Scale bars: 5 µm (A–D); 1 µm (E, F).