Ulnaria hupingensis sp. nov., external view, SEM A a complete valve B middle part detail from A, note central area complete absent C, D two apical details from A, showing two horn-like projections protruding over the oceullulimbus (two arrows, respectively) E, F two other apical details showing two horn-like projections protruding over the ocellulimbus (two arrows, respectively). Scale bars: 20 μm (A); 1 μm (B–F).