Gyrista

Gyrista is a clade of stramenopile protists containing three diverse groups: the mostly photosynthetic Ochrophyta, the parasitic Pseudofungi, and the recently described group of nanoflagellates known as Bigyromonada. Members of this clade are characterized by the presence of a helix or a double helix/ring system in the ciliary transition region.

Systematics

Gyrista was first described in 1998 by protistologist Thomas Cavalier-Smith in his work A revised six-kingdom system of life, originally as a superphylum containing two phyla: Ochrophyta, the heterokont algae; and Bigyra, which then contained the pseudofungi and bigyromonads together with the opalines. Later, the name Bigyra was modified to contain opalines, bicosoecids and labyrinthulomycetes, while the Ochrophyta, Pseudofungi and Bigyromonada remained as groups within Gyrista.

Gyrista was seen in 2017 as the sister group to phylum Bigyra, which contains the Sagenista and Opalozoa. Together, Gyrista and Bigyra form the clade Stramenopiles or Heterokonta.
A phylogenetic analysis in a 2022 preprint recovered a monophyletic Bigyromonada sister to Pseudofungi. The "Bigyra" is paraphyletic:

The 2018 revised taxonomy of Gyrista is the following, with the inclusion of new ochrophyte classes described in 2020 and 2021: