Introvertocystis is an extinct genus of acritarchs. Introvertocystis rangiaotea is from the Late Cretaceous (CenomanianâÂÂTuronian) Tupuangi Formation of the Chatham Islands, New Zealand.
References
John O. Corliss (1984). The kingdom Protista and its 45 phyla, BioSystems, 1984