The ochrophytes, subphylum Ochrophytina, is a group of mostly

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

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 ...

s. Their

plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosy ...

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 discov ...

) divided it into two subphyla,

Phaeista The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic heterokonts. Their plastid is of red algal origin. The classification of the group is still being worked out. Originally, the ochrophytes were regarded as a phylum den ...

Cavalier-Smith 1995 (comprising Hypogyristea and

Chrysista The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic heterokonts. Their plastid is of red algal origin. The classification of the group is still being worked out. Originally, the ochrophytes were regarded as a phylum den ...

in some classifications, or Limnista and Marista in others) and

Khakista The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic heterokonts. Their plastid is of red algal origin. The classification of the group is still being worked out. Originally, the ochrophytes were regarded as a phylum den ...

Cavalier-Smith, 2000 (comprising '' Bolidomonas'' and

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

s). 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 cha ...

, 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, the ...

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

, 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

**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 Synchromophyceae **Superclass

Raphidoistia The raphidophytes, formally known as Raphidomonadea or Raphidophyceae (formerly referred to as Chloromonadophyceae and Chloromonadineae), are a small group of eukaryotic algae that includes both marine and freshwater species. All raphidophytes ...

***Class

Raphidomonadea The raphidophytes, formally known as Raphidomonadea or Raphidophyceae (formerly referred to as Chloromonadophyceae and Chloromonadineae), are a small group of eukaryotic algae that includes both marine and freshwater species. All raphidophytes ...

****Subclass Raphidophycidae ****Subclass Raphopoda **Superclass Fucistia ***Class Aurophyceae ****Subclass Aurearenophycidae ****Subclass Phaeothamniophycidae ***Class

Chrysomerophyceae Chrysomerophyceae is a monotypic class of photosynthetic heterokont eukaryotes. Taxonomy * Class Chrysomerophyceae Cavalier-Smith 1995 ** Order Chrysomeridales O'Kelly & Billard ex Preisig *** Family Chrysomeridaceae Bourrelly 1957 **** Genu ...

***Class Chrysoparadoxophyceae ***Class Phaeosacciophyceae ***Class Schizocladiophyceae ***Class

Phaeophyceae Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and po ...

Fucophyceae ; Melanophyceae (“brown algae”) ****Subclass

Discosporangiophycidae Discosporangiales is an order of brown algae Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown alg ...

****Subclass Ishigeophycidae ****Subclass Dictyotophycidae ****Subclass

Fucophycidae Fucophycidae is a subclass of Phaeophyceae (brown algae) which contains the most complex and evolved orders of Chromista algae. The members of this subclass have stalks with several morphological forms and distinct structures, characterized by ...

***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 filamento ...

_Heterokontae_.html" ;"title="Tribophyceae ; Heterokontae ">Tribophyceae ; Heterokontae (“yellow-green algae”) *Infraphylum Diatomista **Superclass Hypogyrista ***Class

Dictyochophyceae Dictyochophyceae sensu lato is a photosynthetic lineage of heterokont algae. Taxonomy * Class Dictyochophyceae Silva 1980 s.l. ** Subclass Sulcophycidae Cavalier-Smith 2013 *** Order Olisthodiscales Cavalier-Smith 2013 **** Family Olisthodiscac ...

Dictyochia ; Alophycidae ****Subclass

Pedinellia The axodines are a group of unicellular stramenopiles that includes silicoflagellate and rhizochromulinid algae, actinomonad heterotrophic flagellates and actinophryid heliozoa. Alternative classifications treat the dictyochophytes as heterokont ...

Actinochrysophyceae (“axodines”) ****Subclass Pelagophycidae Pelagophyceae_.html" ;"title="Pelagophyceae.html" ;"title="Pelagophyceae">Pelagophyceae ">Pelagophyceae.html" ;"title="Pelagophyceae">Pelagophyceae ****?Subclass Sulcophycidae ***Class Pinguiophyceae **Superclass

***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 Bacillariae ; Bacillariophyceae ****Subclass Corethrophycidae ****Subclass

Rhizosoleniophycidae Rhizosoleniophycidae or Rhizosoleniineae is a grouping of centric diatoms. See also * Coscinodiscineae References SAR supergroup suborders Coscinodiscophyceae {{Diatom-stub ...

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

Notes

References

SAR supergroup phyla {{heterokont-stub