The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic

heterokont Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which a ...

s. Their plastid is of

red algal Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

origin. The classification of the group is still being worked out. Originally, the ochrophytes were regarded as a phylum denominated Ochrophyta. Some authors (e.g.,

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 disc ...

) divided it into two subphyla, Phaeista Cavalier-Smith 1995 (comprising Hypogyristea and Chrysista in some classifications, or Limnista and Marista in others) and Khakista Cavalier-Smith, 2000 (comprising '' Bolidomonas'' and diatoms). Others prefer not to use the subphyla, listing only lower taxa (e.g., Reviers, 2002, Guiry & Guiry, 2014). However, it is currently regarded as a subphylum inside of the phylum

Gyrista 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 ch ...

, along with

Pseudofungi Pseudofungi is a grouping of heterokonts, also known as the Heterokontimycotina. It consists of the Oomycota and Hyphochytridiomycetes. Although numerous biochemical, ultrastructural, and genetic traits clearly place them in the heterokonts, th ...

and

Bigyromonada Bigyromonadea is a recently described non-photosynthetic lineage of Heterokont Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are al ...

. It contains two infraphyla: Diatomista, containing diatoms and related groups, and Chrysista, containing brown and golden algae and related groups.

Phylogeny

The cladogram below shows the evolutionary relationships between all ochrophyte classes. It is based on the latest phylogenetic analyses:

Classification

Below is the present classification of ochrophytes, with the inclusion of three new classes of algae described in 2019, 2020 and 2021. *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. Eust ...

***Class Chrysomonadea Chrysophyceae ***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 ; Melanophyceae (“brown algae”) ****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_.html" ;"title="Tribophyceae ; Heterokontae ">Tribophyceae ; Heterokontae (“yellow-green algae”) *Infraphylum Diatomista **Superclass Hypogyrista ***Class Dictyochophyceae Dictyochia ; Alophycidae ****Subclass Pedinellia Actinochrysophyceae (“axodines”) ****Subclass Pelagophycidae Pelagophyceae_.html" ;"title="Pelagophyceae.html" ;"title="Pelagophyceae">Pelagophyceae ">Pelagophyceae.html" ;"title="Pelagophyceae">Pelagophyceae ****?Subclass Sulcophycidae ***Class Pinguiophyceae **Superclass Khakista ***Class Bolidophyceae ***Class Diatomeae Bacillariae ; Bacillariophyceae ****Subclass Corethrophycidae ****Subclass Rhizosoleniophycidae ****Subclass Eucentricophycidae ****Subclass Bacillariophycidae Pennatia ; =Pennatophycidae*Ochrophytina ''incertae sedis'' **Class Olisthodiscophyceae

Notes

References

SAR supergroup phyla {{heterokont-stub