Pre-normal frustule of Ulnaria ulnabiseriata, external view, SEM A pre-normal valve B middle part detail from A, note its constricted outline in the middle C, D proximal parts of valve from A, note closing plates underdeveloped E, F apical details from A, note slightly inset ocellulimbus. Scale bars: 20 μm (A); 3 μm (B–F).

 
 
  Part of: Liu B (2023) The diatom genus Ulnaria (Bacillariophyta) in China. PhytoKeys 228: 1-118. https://doi.org/10.3897/phytokeys.228.101080