Pterosperma labyrinthus Ostenfeld, 1903, p.578

Now Nematosphaeropsis. Originally Pterosperma, subsequently Pterococcus (an illegitimate generic name), thirdly Coccopterum, fourthly (and now) Nematosphaeropsis.
Tax. sr. synonym of Nematosphaeropsis balcombiana Deflandre and Cookson, 1955, according to Reid, 1974 and Matsuoka, 1983; however, Wrenn, 1988 retained Nematosphaeopsis balcombiana as a separate species. Wrenn, 1988 retained this species in Pterococcus and did not consider it to be a dinoflagellate; however, Fensome et al., 1993 retained the species in Nematosphaeropsis Deflandre and
Cookson, 1955. This is a cyst equivalent of Gonyaulax spinifera (Claparede and Lachmann, 1859) Diesing, 1866, according to Dodge, 1989.

Holotype: Ostenfeld, 1903, fig.12
Age: Recent