From Fensome et al., 2019:
Cleistosphaeridium bulbum Yu Jingxian, 1989, p.140, pl.51, figs.8–9. Holotype: Yu Jingxian, 1989, pl.51, fig.8. NOW Downiesphaeridium?. Originally Cleistosphaeridium, subsequently Downiesphaeridium, thirdly (and now) Downiesphaeridium?. Age: Eocene.

---------------------------------------------------------------------------------------------------