SAR supergroup

Eukaryotic supergroup that comprises stramenopiles, alveolates and rhizarians

"TSAR" redirects here; not to be confused with Tsar or TSAR Publications.

Sar

Temporal range: 736–0 Ma[1]

Pha.

Proterozoic

Archean

Had.

Scientific classification
Domain:  | Eukaryota
Clade:  | Diaphoretickes
Clade:  | Sar
Adl et al., 2012[2]
Unranked clades

* Halvaria
* Stramenopiles (heterokonts)
* Alveolata
* Rhizaria

Synonyms

* Harosa Cavalier-Smith, 2010
* SAR Burki et al., 2007
* RAS Baldauf, 2008

SAR[nb 1] is a highly diverse clade of eukaryotes, often considered a supergroup,[3] that includes stramenopiles (heterokonts), alveolates, and rhizarians.[4][5][6] It is a node-based taxon (under the Sar name), including all descendants of the three groups' last common ancestor,[7] and comprises most of the now-rejected Chromalveolata.[3] Their sister group might be telonemids, with which they would make up the TSAR (sometimes called T-SAR[8][9][10][11]) clade,[12] but this grouping has been challenged.[13][14] Harosa is used synonymously with TSAR by Cavalier-Smith in 2022.[15]

## Etymology

[edit]

The name SAR is an acronym derived from the first letters of its three constituent clades; it has been alternatively spelled RAS.[16] The term Harosa (at the subkingdom level) has also been used, with Stramenopiles replaced by its synonym Heterokonta in this variant of the acronym.[17]

## History of discovery

[edit]

Before the discovery of the SAR supergroup, stramenopiles and alveolates were classified in the supergroup Chromalveolata alongside haptophytes and cryptomonads, being believed to have acquired plastids through secondary endosymbiosis of red algae through a common ancestor.[3] Meanwhile, Rhizaria was traditionally considered to be a separate supergroup. More recent phylogenetic studies confirmed that stramenopiles and alveolates diverged with rhizarians as part of the SAR lineage.[18] This clade has been found by later phylogenomic studies to be robustly characterized compared to other supergroups.[12]

This group excludes haptophytes and cryptomonads, hypothesized to have acquired plastids in separate endosymbiosis events,[19] leading Okamoto et al. (2009) to propose the clade Hacrobia to accommodate them.[20]

## Diversity

[edit]

The SAR supergroup encompasses a variety of morphologies and ecological niches, from microscopic zoo\- and phytoplankton to massive kelp forests. The group includes both photosynthetic and non-photosynthetic forms. Photosynthesis arose independently across various stramenopile and alveolate lineages through secondary or higher-order endosymbiosis events, acquiring plastids of red algal origin,[21][19] while chlorarachniophyte rhizarians captured plastids from green algae, retaining vestigial nucleomorphs.[22]

It has been estimated that SAR encompasses up to half of all eukaryotic diversity.[3]

Owing to the clade's discovery through phylogenomics, there are no known synapomorphies uniting its various members.[4] This was already the case for its subclade Rhizaria, established earlier through similar means. On the other hand, Stramenopiles is well-defined morphologically, characterized by an anterior flagellum with tripartite bristles (mastigonemes), while Alveolata is united by the presence of cortical alveoli.[23]

Nonetheless, studies of telonemids have revealed characteristics such as tripartite hair and peripheral vacuoles, potentially homologous to similar structures in stramenopiles and alveolates. This brings into light the possibility of these structures being ancestrally shared by the clade, with cortical alveoli originating from peripheral vacuoles under this hypothesis.[12]

### Internal phylogeny

[edit]

A 2021 analysis places Alveolata and Stramenopiles in Halvaria, as sister to Rhizaria.[19]

| SAR /  |

|  |

Rhizaria

|

Halvaria |

|  |

Alveolata

|

Stramenopiles

Harosa

## See also

[edit]

* Amoebozoa
* Archaeplastida
* Excavata
* Opisthokonta

## Notes

[edit]

1. ^ As a formal taxon, Sar has only its first letter capitalized, while the earlier abbreviation, SAR, retains all uppercase letters. Both names denote the same group of organisms.[2]

## References

[edit]

1. ^ Laura Wegener Parfrey, Daniel J G Lahr, Andrew H Knoll, Laura A Katz (16 August 2011). "Estimating the timing of early eukaryotic diversification with multigene molecular clocks" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 108 (33): 13624–9\. Bibcode:2011PNAS..10813624P. doi:10.1073/PNAS.1110633108. ISSN 0027-8424. PMC 3158185. PMID 21810989. Wikidata Q24614721.
2. ^ a b Adl, Sina M.; Simpson, Alastair G. B.; Lane, Christopher E.; Lukeš, Julius; Bass, David; Bowser, Samuel S.; Brown, Matthew W.; Burki, Fabien; Dunthorn, Micah; Hampl, Vladimir; Heiss, Aaron; Hoppenrath, Mona; Lara, Enrique; le Gall, Line; Lynn, Denis H. (September 2012). "The Revised Classification of Eukaryotes". Journal of Eukaryotic Microbiology. 59 (5): 429–514\. doi:10.1111/j.1550-7408.2012.00644.x. ISSN 1066-5234. PMC 3483872. PMID 23020233.
3. ^ a b c d Burki, Fabien; Roger, Andrew J.; Brown, Matthew W.; Simpson, Alastair G.B. (January 2020). "The New Tree of Eukaryotes". Trends in Ecology & Evolution. 35 (1): 43–55\. Bibcode:2020TEcoE..35...43B. doi:10.1016/j.tree.2019.08.008. PMID 31606140.
4. ^ a b Burki F, Shalchian-Tabrizi K, Minge M, Skjaeveland A, Nikolaev SI, Jakobsen KS, Pawlowski J (August 2007). Butler G (ed.). "Phylogenomics reshuffles the eukaryotic supergroups". PLOS ONE. 2 (8): e790. Bibcode:2007PLoSO...2..790B. doi:10.1371/journal.pone.0000790. PMC 1949142. PMID 17726520.
5. ^ Hampl V, Hug L, Leigh JW, Dacks JB, Lang BF, Simpson AG, Roger AJ (March 2009). "Phylogenomic analyses support the monophyly of Excavata and resolve relationships among eukaryotic "supergroups"". Proceedings of the National Academy of Sciences of the United States of America. 106 (10): 3859–64\. Bibcode:2009PNAS..106.3859H. doi:10.1073/pnas.0807880106. PMC 2656170. PMID 19237557.
6. ^ Frommolt R, Werner S, Paulsen H, Goss R, Wilhelm C, Zauner S, et al. (December 2008). "Ancient recruitment by chromists of green algal genes encoding enzymes for carotenoid biosynthesis". Molecular Biology and Evolution. 25 (12): 2653–67\. doi:10.1093/molbev/msn206. PMID 18799712.
7. ^ Adl SM, Simpson AG, Lane CE, Lukeš J, Bass D, Bowser SS, et al. (September 2012). "The revised classification of eukaryotes". The Journal of Eukaryotic Microbiology. 59 (5): 429–93\. doi:10.1111/j.1550-7408.2012.00644.x. PMC 3483872. PMID 23020233.
8. ^ Yazaki, Euki; Kume, Keitaro; Shiratori, Takashi; Eglit, Yana; Tanifuji, Goro; Harada, Ryo; Simpson, Alastair G. B.; Ishida, Ken-ichiro; Hashimoto, Tetsuo; Inagaki, Yuji (2020-09-02). "Barthelonids represent a deep-branching metamonad clade with mitochondrion-related organelles predicted to generate no ATP". Proceedings of the Royal Society B: Biological Sciences. 287 (1934): 20201538. doi:10.1098/rspb.2020.1538. PMC 7542792. PMID 32873198.
9. ^ Yazaki, Euki; Yabuki, Akinori; Imaizumi, Ayaka; Kume, Keitaro; Hashimoto, Tetsuo; Inagaki, Yuji (2021-08-31), Phylogenomics invokes the clade housing Cryptista, Archaeplastida, and Microheliella maris, bioRxiv, doi:10.1101/2021.08.29.458128, retrieved 2025-05-17
10. ^ Yazaki, Euki; Yabuki, Akinori; Imaizumi, Ayaka; Kume, Keitaro; Hashimoto, Tetsuo; Inagaki, Yuji (2022-04-13). "The closest lineage of Archaeplastida is revealed by phylogenomics analyses that include Microheliella maris". Open Biology. 12 (4): 210376. doi:10.1098/rsob.210376. PMC 9006020. PMID 35414259.
11. ^ Yazaki, Euki; Harada, Ryo; Isogai, Ryu; Bamba, Kohei; Ishida, Ken-ichiro; Inagaki, Yuji; Shiratori, Takashi (2025-06-04). "Glissandra oviformis n. sp.: a novel predatory flagellate illuminates the character evolution within the eukaryotic clade CRuMs". Open Biology. 15 (6): 250057. doi:10.1098/rsob.250057. PMC 12133344. PMID 40460873.
12. ^ a b c Strassert JF, Jamy M, Mylnikov AP, Tikhonenkov DV, Burki F (April 2019). Shapiro B (ed.). "New Phylogenomic Analysis of the Enigmatic Phylum Telonemia Further Resolves the Eukaryote Tree of Life". Molecular Biology and Evolution. 36 (4): 757–765\. doi:10.1093/molbev/msz012. PMC 6844682. PMID 30668767.
13. ^ Yazaki, Euki; Yabuki, Akinori; Imaizumi, Ayaka; Kume, Keitaro; Hashimoto, Tetsuo; Inagaki, Yuji (2022). "The closest lineage of Archaeplastida is revealed by phylogenomics analyses that include Microheliella maris". Open Biol. 12 (4): 210376. doi:10.1098/rsob.210376. PMC 9006020.
14. ^ Torruella, Guifré; Galindo, Luis Javier; Moreira, David; López-García, Purificación (27 August 2024). "Phylogenomics of neglected flagellated protists supports a revised eukaryotic tree of life". bioRxiv.org. doi:10.1101/2024.05.15.594285. Retrieved 12 November 2024.
15. ^ Cavalier-Smith, Thomas (2022-05-01). "Ciliary transition zone evolution and the root of the eukaryote tree: implications for opisthokont origin and classification of kingdoms Protozoa, Plantae, and Fungi". Protoplasma. 259 (3): 487–593\. doi:10.1007/s00709-021-01665-7. ISSN 1615-6102. PMC 9010356. PMID 34940909.
16. ^ Baldauf SL (2008). "An overview of the phylogeny and diversity of eukaryotes" (PDF). Journal of Systematics and Evolution. 46 (3): 263–273\. doi:10.3724/SP.J.1002.2008.08060 (inactive 12 July 2025). S2CID 512766. Archived from the original (PDF) on 2019-08-20.`{{cite journal}}`: CS1 maint: DOI inactive as of July 2025 (link)
17. ^ 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.
18. ^ Dawkins R, Wong Y (2016). Ancestor's Tale. Houghton Mifflin Harcourt. pp. 573–577\. ISBN 978-0-544-85993-7.
19. ^ a b c Strassert JF; Irisarri I; Williams TA; Burki F (March 2021). "A molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids". Nature Communications. 12 (1): 1879. Bibcode:2021NatCo..12.1879S. doi:10.1038/s41467-021-22044-z. PMC 7994803. PMID 33767194.
20. ^ Burki F (May 2014). "The eukaryotic tree of life from a global phylogenomic perspective". Cold Spring Harbor Perspectives in Biology. 6 (5): a016147. doi:10.1101/cshperspect.a016147. PMC 3996474. PMID 24789819.
21. ^ McFadden, G. I. (2001). "Primary and secondary endosymbiosis and the origin of plastids". Journal of Phycology. 37 (6): 951–959\. Bibcode:2001JPcgy..37..951M. doi:10.1046/j.1529-8817.2001.01126.x. S2CID 51945442.
22. ^ Archibald JM (January 2009). "The puzzle of plastid evolution". Current Biology. 19 (2): R81-8. Bibcode:2009CBio...19..R81A. doi:10.1016/j.cub.2008.11.067. PMID 19174147. S2CID 51989.
23. ^ Grattepanche, Jean David; et al. (March 2018). "Microbial Diversity in the Eukaryotic SAR Clade: Illuminating the Darkness Between Morphology and Molecular DataDarkness Between Morphology and Molecular Data". BioEssays. doi:10.1002/bies.201700198.

* v
* t
* e

Eukaryote classification

Domain
Archaea
Bacteria
Eukaryota
(major groups
Metamonada
Discoba
Diaphoretickes

Hacrobia

Cryptista
Rhizaria
Alveolata
Stramenopiles
Plants
Amorphea

Amoebozoa
Opisthokonta

Animals
Fungi
Mesomycetozoea)

Amorphea

| Amoebozoa|

* Discosea
* Tubulinea
* Variosea
* Archamoebea
* Cutosea
* Eumycetozoa (true slime molds)

|

Obazoa

* Apusomonadida
* Breviatea

Opisthokonta

| Holomycota|

* Rotosphaerida
* Fungi¹

|

Holozoa

* Tunicaraptor
* †Bicellum
* Ichthyosporea
* Pluriformea

Filozoa|

* Filasterea

Choanozoa|

* Choanoflagellata
* Animalia (animals)¹

Diaphoretickes

* Telonemia

| Haptista|

* Centroplasthelida
* Haptophytina

|

SAR

| Rhizaria|

* Cercozoa
* Endomyxa
* Retaria
* Foraminifera
* Radiolaria*

|

Alveolata|

* Colponemida*
* Ciliophora (ciliates)

Myzozoa|

* Apicomplexa
* Chrompodellida
* Dinoflagellata
* Perkinsozoa

Stramenopiles|

* Platysulcus
* Kaonashia

Bigyra*|

* Bicosoecida
* Placidozoa
* Sagenista

Gyrista|

* Developea
* Pirsoniales
* Hyphochytriomycetes
* Ochrophyta (brown algae, diatoms and relatives)
* Oomycetes (water molds)
* Actinophryida

CAM

| Pancryptista|

* Microheliella

Cryptista|

* Palpitomonas
* Katablepharidida
* Cryptomonada

Archaeplastida
(plants sensu lato)|

* Picozoa
* Rhodophyta (red algae)
* Rhodelphidia
* Glaucophyta

| Viridiplantae
(green plants or
plants sensu stricto)|

* Prasinodermophyta
* Chlorophyta

| Streptophyta|

* Mesostigmatophyceae
* Chlorokybophyceae
* Spirotaenia
* Klebsormidiophyceae
* Charophyceae
* Coleochaetophyceae
* Zygnematophyceae
* Embryophyta (land plants or plants sensu strictissimo)¹

|

"Excavates"*

| Discoba|

* Jakobea
* Tsukubamonas

Discicristata|

* Heterolobosea
* Euglenozoa

Metamonada*|

* Anaeramoebidae
* Parabasalia
* Barthelona
* Skoliomonas
* Fornicata
* Preaxostyla

Malawimonadida|

* Malawimonadidae
* Imasidae

Incertae sedis

| Provora|

* Nebulidia
* Nibbleridia

|

Hemimastigophora|

* Spironematellidae
* Paramastigidae

Ancyromonadida|

* Ancyromonadidae
* Planomonadidae
* Divimonas

CRuMs|

* Diphylleida
* Mantamonadida
* Rigifilida
* Glissandrida

Genera of
uncertain affiliation|

* Acinetactis
* Actinastrum
* Berkeleyaesol
* Kamera
* Magosphaera
* Meringosphaera
* Meteora
* Parakaryon (?)
* Quasibodo
* Tetrahelia

Acritarchs
and other fossils|

* †Algospongia
* †Archaeochaeta
* †Cephalonyx
* †Changchengia
* †Cheleutochroa
* †Chitinozoa
* †Coryphidium
* †Cucumiforma
* †Dictyosphaera
* †Diskagma (?)
* †Eosolena
* †Francevillian biota (?)
* †Germinosphaera
* †Grandilingulata
* †Granomarginata
* †Grypania
* †Gunflint microbiota
* †Horodyskia
* †Introvertocystis
* †Korilophyton
* †Leiosphaeridia
* †Navifusa
* †Portalites
* †Protosterol biota
* †Pterospermopsimorpha
* †Qingshania
* †Quadrisporites
* †Schizofusa
* †Shuiyousphaeridium
* †Simia
* †Tappania
* †Tawuia (?)
* †Tetraporina
* †Thuchomyces (?)
* †Tuanshanzia
* †Valeria
* †Vernanimalcula

* ¹non-protist groups
* *possibly paraphyletic groups
* bold denotes groups with over 1,000 species

* Taxonomy of protists

Taxon identifiers

Harosa|

* Wikidata: Q18397957
* Wikispecies: Harosa
* AlgaeBase: 142011
* IRMNG: 11904991
* ITIS: 969910
* NBN: NHMSYS0021057654
* NCBI: 2698737
* NZOR: 0096df19-0000-484f-af50-4f6e83859ff7
* Open Tree of Life: 5246039
* Paleobiology Database: 325035
* WoRMS: 582419

*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template