Gyrista is a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

stramenopile The stramenopiles, also called heterokonts, are protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, an ...

protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...

s containing three diverse groups: the mostly

photosynthetic Photosynthesis ( ) is a Biological system, system of biological processes by which Photoautotrophism, photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical ener ...

Ochrophyta Ochrophytes, also known as heterokontophytes or stramenochromes, are a phylum of algae. They are the photosynthetic stramenopiles, a group of eukaryotes, organisms with a cell nucleus, characterized by the presence of two unequal flagella, one o ...

, 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 Thomas (Tom) Cavalier-Smith, FRS, FRSC, NERC Professorial Fellow (21 October 1942 – 19 March 2021), was a professor of evolutionary biology in the Department of Zoology, at the University of Oxford. His research has led to discov ...

in his work ''A revised six-kingdom system of life'', originally as a

superphylum In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclat ...

containing two

phyla Phyla, the plural of ''phylum'', may refer to: * Phylum, a biological taxon between Kingdom and Class * by analogy, in linguistics, a large division of possibly related languages, or a major language family which is not subordinate to another Phy ...

, the

heterokont The stramenopiles, also called heterokonts, are protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, an ...

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

; and

Bigyra Bigyra () is a phylum of microscopic eukaryotes that are found at the base of the Stramenopiles clade. It includes three well-known heterotrophic groups Bicosoecida, Opalinata and Labyrinthulomycetes, as well as several small clades initially disc ...

, which then contained the pseudofungi and

bigyromonad Bigyromonada is a recently described non-photosynthetic lineage of stramenopiles that at present contains two classes. Description Bigyromonads are characterized by biciliate cells that feed on bacteria through phagotrophy. They are marine li ...

s 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

, which contains the Sagenista and Opalozoa. Together, Gyrista and Bigyra form the superphylum

Stramenopiles The stramenopiles, also called heterokonts, are Protist, protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular sur ...

or Heterokonta. A phylogenetic analysis in 2022 recovered a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

Bigyromonada sister to Pseudofungi. The "Bigyra" is

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

Classification

The 2018 revised taxonomy of Gyrista is the following, with the inclusion of new

ochrophyte Ochrophytes, also known as heterokontophytes or stramenochromes, are a phylum of algae. They are the photosynthetic stramenopiles, a group of eukaryotes, organisms with a cell nucleus, characterized by the presence of two unequal flagella, one o ...

classes described in 2020 and 2021: *Subphylum Bigyromonada **Class

Developea Bigyromonada is a recently described non-photosynthetic lineage of stramenopiles that at present contains two classes. Description Bigyromonads are characterized by biciliate cells that feed on bacteria through phagotrophy. They are marine li ...

Bigyromonadea **Class Pirsonea *Subphylum Pseudofungi Heterokontimycotina **Class Hyphochytrea Hyphochytriomycota **Class Oomycetes Oomycota ; Peronosporomycetes *Subphylum Ochrophytina Heterokontophyta ; Stramenochromes **Infraphylum Chrysista ***Superclass Limnistia ****Class

Eustigmatophyceae Eustigmatophytes are a small group (17 genera; ~107 species) of eukaryotic forms of algae that includes marine, freshwater and soil-living species. All eustigmatophytes are unicellular, with coccoid cells and polysaccharide cell walls. Eus ...

****Class Chrysomonadea Chrysophyceae ****Class

Picophagea Picophagea, also known as Synchromophyceae, is a class of photosynthesis, photosynthetic stramenopiles. The chloroplast of the Synchromophyceae are surrounded by two membranes and arranged in a way where they share the outer pair of membranes. Th ...

Synchromophyceae ">Synchromophyceae.html" ;"title="Synchromophyceae">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 ; Melanophyceae *****Subclass Discosporangiophycidae *****Subclass Ishigeophycidae *****Subclass Dictyotophycidae *****Subclass Fucophycidae ****Class

Xanthophyceae Yellow-green algae or the Xanthophyceae (xanthophytes) are an important group of heterokont algae. Most live in fresh water, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filamen ...

Heterokontae ">Tribophyceae ; Heterokontae **Infraphylum Diatomista ***Superclass Hypogyrista ****Class Dictyochophyceae Dictyochia ; Alophycidae *****Subclass Pedinellia Actinochrysophyceae ; Axodines*****Subclass Pelagophycidae *****?Subclass Sulcophycidae – ?'' Sulcochrysis'' ****Class Pinguiophyceae ***Superclass Khakista ****Class

Bolidophyceae Bolidophyceae is a class of photosynthetic heterokont picophytoplankton, and consist of less than 20 known species. They are distinguished by the angle of flagellar insertion and swimming patterns as well as recent molecular analyses. Bolidophyce ...

****Class Diatomeae

Bacillariophyceae Bacillariophyceae is a class of diatoms. Previously, this class was equivalent to Diatomeae, the taxonomic name for all diatoms. However, due to both the known and estimated diversity of diatoms, since 2019 they have been expanded to several class ...

*****Subclass Corethrophycidae *****Subclass Rhizosoleniophycidae *****Subclass Eucentricophycidae *****Subclass Bacillariophycidae Pennatia ; =Pennatophycidae**Ochrophytina incertae sedis ***Class Olisthodiscophyceae

Notes

References

{{Taxonbar, from=Q21446106 Stramenopile taxa