A–F Navicula winoniformis Chudaev, Glushchenko, Kulikovskiy & Kociolek, sp. nov. SEM. Sample no 03572. A–C external views D–F internal views A, D the whole valve B, E central area C, F valve end. A black arrows show the terminal raphe fissures. White arrow shows the indistinct kink of raphe branch B white arrows show central raphe pores. Black arrow shows the very slightly elevated raphe-sternum C black arrow shows the terminal raphe fissure. White arrow shows the longitudinal grooves where areola openings are located. White arrowheads show the small isolated apical areolae D white arrows show the accessory rib E black arrow shows the rectangular areola opening. Black arrowhead shows the circular areola opening. White arrows show the central raphe endings. White arrowhead shows the raphe slit F black arrows show the stria which are slightly wider than virgae. White arrow shows the helicroglossa. White arrowheads show the small isolated apical areolae. Scale bars: 5 μm (A); 2 μm (B–E); 1 μm (F).