Ulnaria wuling-biseriata, sp. nov., internal view, SEM A a valve with a valvocopula B middle detail from A. C, D two apical details of A, note the valvocopula unornamented at each apex E, F details of the valvocopula, note its closed nature and the shelf-like projection (F, arrow). Scale bars: 20 μm (A); 2 μm (B–F).