Chromista is a eukaryotic kingdom, probably polyphyletic.[1][2] It includes all algae whose chloroplasts contain chlorophylls a and c, as well as various colorless forms that are closely related to them. As it is assumed the last common ancestor already possessed chloroplasts of red algal origin, the non-photosynthetic forms evolved from ancestors able to perform photosynthesis.[3] These chloroplasts are surrounded by four membranes, and are believed to have been acquired from some red algae.

Scientific classification



Chromista has been defined in different ways at different times. The name Chromista was first introduced by Cavalier-Smith in 1981;[4] the earlier names Chromophyta, Chromobiota and Chromobionta correspond to roughly the same group.

It has been described as consisting of three different groups:[5]

In 2010, Thomas Cavalier-Smith indicated his desire to move Alveolata, Rhizaria and Heliozoa into Chromista.[6]

Some examples of classification of the Chromista and related groups are shown below.[7][8]

Chromophycées (Chadefaud, 1950)

The Chromophycées (Chadefaud, 1950),[9] renamed Chromophycota (Chadefaud, 1960),[10] included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta (included in Chrysophyceae until Christensen, 1962), Cryptophyta, Dinophyta, Euglenophyceae and Choanoflagellida (included in Chrysophyceae until Hibberd, 1975).

Chromophyta (Christensen 1962, 1989)

The Chromophyta (Christensen 1962, 1989), defined as algae with chlorophyll c, included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta, Cryptophyta, Dinophyta and Choanoflagellida. The Euglenophyceae were transferred to the Chlorophyta.

Chromophyta (Bourrelly, 1968)

The Chromophyta (Bourrelly, 1968) included the current Ochrophyta (autotrophic Stramenopiles), Haptophyta and Choanoflagellida. The Cryptophyceae and the Dinophyceae were part of Pyrrhophyta (= Dinophyta).

Chromista (Cavalier-Smith, 1981)

The Chromista (Cavalier-Smith, 1981) included the current Stramenopiles, Haptophyta and Cryptophyta.

Chromalveolata (Adl et al., 2005)

The Chromalveolata (Cavalier-Smith, 1981) included Stramenopiles, Haptophyta, Cryptophyta and Alveolata.

Chromista (Cavalier-Smith, 2010)

The Chromista (Cavalier-Smith, 2010) included SAR (Stramenopiles, Alveolata and Rhizaria) and Hacrobia (Haptista, Cryptista). A new classification of classes and phyla within Chromista was proposed by Cavalier-Smith in 2017.[3]



Corbihelia Cavalier-Smith 2015

Cryptophyta Silva 1962


Centroheliozoa Cushman & Jarvis 1929 sensu Durrschmidt & Patterson 1987

Haptophyta Hibberd 1976 emend. Edvardsen & Eikrem 2000

SAR supergroup

Phytomyxea Engler & Prantl 1897 em. Cavalier-Smith 1993

Vampyrellidea Cavalier-Smith 2017

Filosa Leidy 1879 emend. Cavalier-Smith 2003 stat. nov.

Retaria Cavalier-Smith 1999 emend. Cavalier-Smith 2017


Ciliophora Doflein 1901 stat. n. Copeland 1956

Miozoa Cavalier-Smith 1987


Platysulcea Cavalier-Smith 2017

Sagenista Cavalier-Smith 1995 stat. n. 2006

Bikosea Cavalier-Smith 2013

Placidozoa Cavalier-Smith 2013


Bigyromonadea Cavalier-Smith 1998

Peronosporomycota Dick 1995

Hyphochytriomycota Whittaker 1969

Pirsonea Cavalier-Smith 2017

Ochrophyta Cavalier-Smith 1986

History and controversy

Molecular trees have had some difficulty resolving relationships between the different groups. All three may share a common ancestor with the alveolates (see chromalveolates), but there is evidence that suggests that the haptophytes and cryptomonads do not belong together with the heterokonts or the SAR clade, but may be associated with the Archaeplastida.[1][11] Cryptista specifically may be sister or part of Archaeplastida.[12]

See also


  1. Parfrey LW, Barbero E, Lasser E, Dunthorn M, Bhattacharya D, Patterson DJ & Katz LA (December 2006). "Evaluating support for the current classification of eukaryotic diversity". PLoS Genetics. 2 (12): e220. doi:10.1371/journal.pgen.0020220. PMC 1713255. PMID 17194223.
  2. Cavalier-Smith T, Allsopp MT, Chao EE (November 1994). "Chimeric conundra: are nucleomorphs and chromists monophyletic or polyphyletic?". Proceedings of the National Academy of Sciences of the United States of America. 91 (24): 11368–72. Bibcode:1994PNAS...9111368C. doi:10.1073/pnas.91.24.11368. PMC 45232. PMID 7972066.
  3. Cavalier-Smith T (January 2018). "Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences". Protoplasma. 255 (1): 297–357. doi:10.1007/s00709-017-1147-3. PMC 5756292. PMID 28875267.
  4. Cavalier-Smith T (1981). "Eukaryote kingdoms: seven or nine?". Bio Systems. 14 (3–4): 461–81. doi:10.1016/0303-2647(81)90050-2. PMID 7337818.
  5. Csurös M, Rogozin IB, Koonin EV (May 2008). "Extremely intron-rich genes in the alveolate ancestors inferred with a flexible maximum-likelihood approach". Molecular Biology and Evolution. 25 (5): 903–11. doi:10.1093/molbev/msn039. PMID 18296415.
  6. Cavalier-Smith T (June 2010). "Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree". Biology Letters. 6 (3): 342–5. doi:10.1098/rsbl.2009.0948. PMC 2880060. PMID 20031978.
  7. de Reviers B (2006). Biologia e Filogenia das Algas. Porto Alegre: Editora Artmed. pp. 156–157. ISBN 9788536315102.
  8. Blackwell W (2009). "Chromista revisited: a dilemma of overlapping putative kingdoms, and the attempted application of the botanical code of nomenclature" (PDF). Phytologia. 91 (2): 191–225.
  9. Chadefaud M (1950). "Les cellules nageuses des Algues dans l'embranchement des Chromophycées" [Seaweed swimming cells in the branch of Chromophyceae]. Comptes rendus hebdomadaires des séances de l'Académie des Sciences (in French). 231: 788–790.
  10. Chadefaud M (1960). "Les végétaux non vasculaires (Cryptogamie)". In Chadefaud M, Emberger L (eds.). Traité de Botanique Systématique. Paris: Tome I.
  11. Burki F, Shalchian-Tabrizi K, Minge M, Skjaeveland A, Nikolaev SI, Jakobsen KS, Pawlowski J (August 2007). "Phylogenomics reshuffles the eukaryotic supergroups". PLOS ONE. 2 (8): e790. Bibcode:2007PLoSO...2..790B. doi:10.1371/journal.pone.0000790. PMC 1949142. PMID 17726520.
  12. Burki F, Kaplan M, Tikhonenkov DV, Zlatogursky V, Minh BQ, Radaykina LV, Smirnov A, Mylnikov AP, Keeling PJ (January 2016). "Untangling the early diversification of eukaryotes: a phylogenomic study of the evolutionary origins of Centrohelida, Haptophyta and Cryptista". Proceedings. Biological Sciences. 283 (1823): 20152802. doi:10.1098/rspb.2015.2802. PMC 4795036. PMID 26817772.
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