Gyrista Explained

Gyrista is a phylum of heterokont 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 phylum are characterized by the presence of a helix or a double helix/ring system in the ciliary transition region.

Systematics

Taxonomic history

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.

Molecular phylogenetics

Gyrista was seen in 2017 as the sister group to phylum Bigyra, which contains the Sagenista and Opalozoa. Together, Gyrista and Bigyra form the superphylum Stramenopiles or Heterokonta.

A phylogenetic analysis in 2022 recovered a monophyletic Bigyromonada sister to Pseudofungi. The "Bigyra" is paraphyletic:

Classification

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

• • • Subphylum Bigyromonada Class Developea [=Bigyromonadea {{au|Cavalier-Smith 1997}}]
    • Class Pirsonea Subphylum Pseudofungi [=Heterokontimycotina {{au|M.W. Dick 1976}}]
  • Class Hyphochytrea [=Hyphochytriomycota {{au|Whittaker 1969}}]
  • Class Oomycetes [=Oomycota {{au|Arx 1967}}; Peronosporomycetes {{au|M.W. Dick 2001}}]
• Subphylum Ochrophytina [=Heterokontophyta {{au|van den Hoek ''et al.'' 1978}}; Stramenochromes {{au|Leipe ''et al.'' 1994}}]
  • • • • • • • • • • • • Infraphylum Chrysista Superclass Limnistia Class Eustigmatophyceae Class Chrysomonadea [=Chrysophyceae {{au|Pascher 1914}}]
      • Class Picophagea [=[[Synchromophyceae]] ]
        • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Superclass Raphidoistia Class Raphidomonadea Subclass Raphidophycidae Subclass Raphopoda Superclass Fucistia Class Aurophyceae Subclass Aurearenophycidae Subclass Phaeothamniophycidae Class Chrysomerophyceae Class Chrysoparadoxophyceae Class Phaeosacciophyceae Class Schizocladiophyceae Class Phaeophyceae [=Fucophyceae {{small|Warming 1884}}; Melanophyceae {{au|Rabenhorst 1863}}]
        • Subclass Discosporangiophycidae
          • • • • • • • • • • • • • • Subclass Ishigeophycidae Subclass Dictyotophycidae Subclass Fucophycidae Class Xanthophyceae [=Tribophyceae {{au|Hibberd 1981}};<ref name="Tribophyceae"/> Heterokontae {{au|Luther 1899}}]
                • Infraphylum Diatomista Superclass Hypogyrista Class Dictyochophyceae [=Dictyochia {{au|Haeckel 1894}}; Alophycidae {{au|Cavalier-Smith 2006}}]
        • Subclass Pedinellia [=Actinochrysophyceae {{au|Cavalier-Smith 1995}}; Axodines]
          • • • • • Subclass Pelagophycidae ?Subclass Sulcophycidae – ?Sulcochrysis
                    • Class Pinguiophyceae Superclass Khakista Class Bolidophyceae
      • Class Diatomeae [=Bacillariophyceae]
        • • • • • • • • • • • • • • • • Subclass Corethrophycidae Subclass Rhizosoleniophycidae Subclass Eucentricophycidae Subclass Bacillariophycidae [=Pennatia {{au|Pennatia Schütt 1896}}; =Pennatophycidae]
  • Ochrophytina incertae sedis