Ulnaria jishou-biseriata sp. nov., internal view, SEM A a valve with valvocopula B, C middle details from A, note serrated projections over each virga (C, arrows) D, E two apical details from A, note unornamented valvocopula at both apices (arrow respectively). Scale bars: 20 μm (A); 2 μm (B, D, E); 1 μm (C).