Van Geel et al. 1981: The hyaline, discoid theca 26-35 μm in diameter. The radial striation may be artificial contraction ridges of the wall resulting from the preliminary treatment for pollen analysis.
van Geel B, Bohncke SJP, Dee H (1981) A palaecological study of an upper Late Glacial and Holocene sequence from 'De Borchert', The Netherlands. Rev. Palaeobot. Palynol. 31:367-448.