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Protist classification

Classification of eukaryotes From Wikipedia, the free encyclopedia

A protist (/ˈprtɪst/) is any eukaryotic organism (one with cells containing a nucleus) that is not an animal, plant, or fungus. The protists do not form a natural group, or clade, since they exclude certain eukaryotes with whom they share a common ancestor;[a] but, like algae or invertebrates, the grouping is used for convenience. In some systems of biological classification, such as the five-kingdom scheme proposed by Robert Whittaker in 1969, the protists make up a kingdom called Protista, composed of "organisms which are unicellular or unicellular-colonial and which form no tissues".[1][b] In the 21st century, the classification shifted toward a phylogenetic classification of protists.[2]

Phylogenomic tree of eukaryotes, as regarded in 2025.

The following groups contain protists. The clade Opisthokonta also contains the animals and the fungi, and the Archaeplastida also contains plants.

Cavalier-Smith's classification

Thomas Cavalier-Smith and his collaborators use a fully rank-based classification of protists. Here is their classification:[3][4][5][6][7][8][9][10][11]

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Current classification

Legend:

Extinct, or exclusively fossil taxon.
(P) Paraphyletic or polyphyletic taxon.
(P?) Potentially paraphyletic or polyphyletic taxon.
(=...) Taxonomic synonym.
(...) Same taxon in a different code of nomenclature.

Amorphea

The supergroup Amorphea contains very diverse heterotrophic organisms, from the macroscopic fungi and animals to the unicellular choanoflagellates and classical amoebae. They frequently exhibit the ability to produce multinucleated cells, a trait considered ancestral to Amorphea. They are also capable of producing pseudopodia, as does the closely related CRuMs clade, forming the clade Podiata.[12]

Amorphea is divided into two clades: Amoebozoa, containing well-known amoebae and slime molds, and Obazoa, containing animals, fungi, and their closest relatives. The relationship between these two clades was initially called 'Unikonta', due to a hypothesis where their common ancestor was a unikont, i.e., a eukaryote with just one flagellum.[13] However, this hypothesis was refuted, as there are bikont amorpheans (e.g., Breviata anathema) and it likely is not an ancestral trait to have a single flagellum.[14][15]

Obazoa

Breviatea

Cladogram of Obazoa based on several analyses.[16][17][18]

The clade Obazoa contains two small groups of flagellates, the breviates and the apusomonads, and the large clade Opisthokonta, which contains animals, fungi, and their closest protist relatives.[6] Under the Cavalier-Smith system, breviates and apusomonads were two classes that composed the phylum Apusozoa,[4] but this taxon is paraphyletic, as apusomonads are more closely related to opisthokonts.[16] The taxonomy of apusomonads was expanded in a 2022 phylogenetic study that introduced many new genera.[19]

Opisthokonta

Opisthokonts are divided into two branches: Holozoa (animal-related), containing the ichthyosporeans, pluriformeans, filastereans and choanoflagellates; and Nucletmycea or Holomycota (fungus-related), containing the nucleariids and opisthosporidians. These groups, minus opisthosporidians, were classified as different classes within the paraphyletic phylum Choanozoa in the system of Cavalier-Smith, now obsolete. Instead, Choanozoa is the name used for the clade containing choanoflagellates and animals. Opisthosporidians (aphelids, rozellids and microsporidians) are often studied as protists, but are also considered fungi by protistologists[6] and mycologists alike.[20] Both Holozoa and Nucletmycea have been proposed once as superkingdoms by a group of mycologists who classified nucleariids and fungi as kingdoms, but without any mention of holozoan kingdoms.[21]

Amoebozoa

Cladogram of the major groups of Amoebozoa based on an 824-gene phylogenetic analysis published in 2022.[32]

The phylum Amoebozoa contains around 2,400 species[33] of primarily amoeboid protists.[6] It includes a large portion of the traditional Sarcodina, the taxon uniting all amoebae. In particular, it groups naked and testate lobose amoebae (the traditional Lobosa), as well as the archamoebae and eumycetozoans (slime molds), and a few flagellates.[34] After the general 2019 revisions published by the International Society of Protistologists (ISOP),[6] there have been specific revisions to the classification of eumycetozoans[35] and testate amoebae.[36]

Phylum Amoebozoa Lühe 1913 sensu Cavalier-Smith 1998. Genera incertae sedis: Belonocystis, Boveella, Biomyxa, Corallomyxa, Gibbodiscus, Hartmannia, Malamoeba, Malpighamoeba, Oscillosignum, Pseudothecamoeba, Rhabdamoeba, Schoutedamoeba, Stereomyxa, Subulamoeba, Triaenamoeba, Unda.[6]

  • Evosea Kang et al. 2017
    • Class Cutosea Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2016, order Squamocutida Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2016
    • Class Variosea Cavalier-Smith 2004. Genera not assigned to any lower clade: Angulamoeba, Arboramoeba, Darbyshirella, Dictyamoeba, Ischnamoeba, Heliamoeba, Filamoeba, Phalansterium.[f]
      • Family Flamellidae Lahr & Katz in Lahr et al. 2011, genera Flamella (=Comandonia),[52] Telaepolella Lahr et al. 2012.
      • Order Protosteliida (Protosteliales) L.S.Olive & Stoian. 1966 sensu Shadwick & Spiegel in Adl et al. 2012, family Protosteliidae (Protosteliaceae) L.S.Olive & Stoian. 1966, genus Protostelium (incl. Planoprotostelium).
      • Order Fractovitellida Lahr et al. 2011 sensu Kang et al. 2017
        • Family Acramoebidae Smirnov, Nassonova & Cavalier-Smith 2008, genus Acramoeba.
        • Family Schizoplasmodiidae Shadwick & Spiegel in Adl et al. 2012, genera Ceratiomyxella, Nematostelium, Schizoplasmodium.
        • Family Soliformoviidae Lahr & Katz 2011. Genera: Soliformovum Spiegel 1995; Grellamoeba Dyková, Kostka & Pecková 2008.
      • Order Cavosteliida (Cavosteliales) Shadwick & Spiegel in Adl et al. 2012, family Cavosteliidae (Cavosteliaceae) Olive & Stoianovitch 1964, genera Cavostelium, Schizoplasmodiopsis, Tychosporium.
      • Order Holomastigida Lauterborn 1895, family Multiciliidae Poche 1913, genus Multicilia.
      • Order Artodiscida Cavalier-Smith 2013, family Artodiscidae Cavalier-Smith 2013, genera Artodiscus, Tetracilia.
    • Class Archamoebea Cavalier-Smith 1983 sensu Pánek et al. 2016[53]
    • Eumycetozoa Zopf 1884 sensu Kang et al. 2017 (=Mycetozoa de Bary 1859 ex Rostafinski 1873, Macromycetozoa Fiore-Donno 2010)
      • Class Dictyostelea Lister 1909 sensu Sheikh et al. 2018 (Dictyosteliomycetes Doweld 2001). Genus unassigned to any order: Synstelium. Genus incertae sedis: Coenonia.[55]
        • Order Acytosteliales S.Baldauf S.Sheikh & Thulin 2018
          • Family Acytosteliaceae Raper ex Raper & Quinlan 1958, genera Acytostelium, Rostrostelium, Heterostelium.
          • Family Cavenderiaceae S.Baldauf, S.Sheikh & Thulin 2018, genus Cavenderia.
        • Order Dictyosteliales L.S.Olive ex P.M.Kirk et al. 2001. Genus unassigned to any family: Coremiostelium.
          • Family Dictyosteliaceae Rostaf. ex Cooke 1877, genera Dictyostelium, Polysphondylium.
          • Family Raperosteliaceae S.Baldauf S.Sheikh & Thulin 2018, genera Hagiwaraea, Raperostelium, Speleostelium, Tieghemostelium.
      • Class Ceratiomyxomycetes (Ceratiomyxea) D. Hawksw., B. Sutton & Ainsw. 2019,[35] order Protosporangiida Shadwick & Spiegel in Adl et al. 2012 (Ceratiomyxales G.W. Martin ex M.L. Farr & Alexop.)
      • Class Myxogastrea Cavalier-Smith 1993 (Myxomycetes G.Winter 1880) (=Myxogastres Fr. 1829, Myxogasteres Schröt., 1889, Endosporeae Rostaf. 1873, Myxogastromycetidae G.W.Martin 1961, Myxogastromycetes M.Locquin 1974, Myxogastria Cavalier-Smith 2012 as "Myxogastria L.S.Olive 1970" nom. inval.)[35]

Archaeplastida

The clade Archaeplastida encompasses photosynthetic eukaryotes whose chloroplasts are derived from an event of primary endosymbiosis with a cyanobacterium. This includes the multicellular land plants (embryophytes), distinguished by their embryonic development and differentiation into tissues, and a multitude of protist lineages, many of which have also evolved multicellularity independently (e.g., red algae). Together, they amount to an estimated 500,000 species, with protists covering less than 50,000. In some systems of classification, Archaeplastida is equivalent to the plant kingdom (Plantae).[4] As such, the protist lineages, including simple, single-celled algae and protozoa, are regarded as "plants" under this definition.[57] Other definitions exclude these protists, and reduce the plant kingdom to only embryophytes.[6]

Rhodophyta

Cladogram showing the relationships between red algal classes, according to a 2017 phylogenomic analysis.[58]

The red algae, formally known as phylum Rhodophyta, are a group of more than 7,100 species of photosynthetic eukaryotes containing primary plastids. They have evolved into diverse morphologies, from single coccoid cells to large pseudoparenchymatous thalli that have complex life cycles with up to three generations.[59] Unlike other eukaryotes, they lack flagella and centrioles in all their life stages.[60]

Traditionally, red algae have been classified according to morphology as two classes (Bangiophyceae and Florideophyceae), or two subclasses (Bangiophycidae and Florideophycidae) of a single class Rhodophyceae. This system was challenged with the rise of molecular phylogenetics, which revealed the paraphyly of Bangiophyceae. In addition, a third class, Cyanidiophyceae, was discovered as the earliest diverging lineage. In 2004 a new molecular-based classification of red algae was proposed, where they composed a subkingdom of plants (Rhodoplantae) divided into two phyla: Cyanidiophyta, with just one class, and Rhodophyta, with three subphyla (Rhodellophytina, Metarhodophytina and Eurhodophytina) and four classes, one of which was still paraphyletic.[61] In 2006, a comprehensive molecular analysis revised the classification and proposed a single phylum Rhodophyta with two subphyla: Cyanidiophytina, with one class, and Rhodophytina, with six classes.[62] This taxonomic system, developed by Hwan Su Yoon and collaborators, is the prevalent among taxonomists,[63][59] with the addition of a separation of subphylum Rhodophytina into two subphyla Proteorhodophytina and Eurhodophytina in 2017.[58] In 2022, a book was published revising the classification of all freshwater red algae.[64]

Phylum Rhodophyta Wettstein 1901

Rhodelphidia

Phylum Rhodelphidia Tikhonenkov, Gawryluk, Mylnikov & Keeling 2019 → class Rhodelphidea Tikhonenkov, Gawryluk, Mylnikov & Keeling 2019 → order Rhodelphida Tikhonenkov, Gawryluk, Mylnikov & Keeling 2019 → family Rhodelphidae Tikhonenkov, Gawryluk, Mylnikov & Keeling 2019. Sole genus: Rhodelphis Tikhonenkov, Gawryluk, Mylnikov & Keeling 2019.[91]

Picozoa

Phylum Picozoa Seenivasan, Sausen, Medlin & Melkonian 2013 (=picobiliphytes Not et al. 2007) → class Picomonadea Seenivasan, Sausen, Medlin & Melkonian 2013 → order Picomonadida Seenivasan, Sausen, Medlin & Melkonian 2013 → family Picomonadidae Seenivasan, Sausen, Medlin & Melkonian 2013. Sole genus: Picomonas Seenivasan, Sausen, Medlin & Melkonian 2013.[11][h]

Glaucophyta

Phylum Glaucophyta Skuja 1954 (=Glaucocystaceae West 1904, Glaucocystophyta Kies and Kremer 1986, Glaucoplantae Marin & Melkonian in Li et al. 2020). Incertae sedis genera: Archaeopsis, Chalarodora, Glaucocystopsis, Peliaina, Strobilomonas.[93]

Chloroplastida

Cladogram of Chloroplastida with focus on the classes of green algae, based on 2019–2023 phylogenetic studies. Prasinophytes are marked *.[94][95][96]

The green algae are a paraphyletic group from which land plants (Embryophyta) evolved. Together they form the clade Chloroplastida (in reference to their green plastids), also known as Viridiplantae (meaning "green plants"). Green algae were originally studied as a single division Chlorophyta.

Prasinodermophyta

Division Prasinodermatophyta Marin & Melkonian in Li et al. 2020 (as Prasinodermophyta)[95]

Chlorophyta

Division Chlorophyta Reichenbach 1828 emend. Pascher 1914 emend. Lewis & McCourt 2004

Streptophyta

Division Streptophyta Bremer & Wanntorp 1981 (=Charophyta Migula 1897 emend. Karol et al. 2009)

Pancryptista

Cladogram of Pancryptista based on 2020 and 2022 analyses.[131][132]

The phylum Cryptista contains heterotrophic and photosynthetic single-celled flagellates. Its classification has undergone many changes through the years, and several conflicting systems and nomenclatures coexist. It was described by Thomas Cavalier-Smith in 1989 to unite two distinct groups of flagellates: the photosynthetic cryptomonads, and the heterotrophic goniomonads (respectively the two classes Cryptomonadea and Cyathomonadea). The name Cryptista was meant to be a synonym of Cryptophyta,[133] the algal Phylum described by the same author in previous years.[134] In 2004, he modified the classification of Cryptista to add two subphyla: Cryptomonada, containing the aforementioned classes (renamed as Cryptophyceae and Goniomonadea respectively), and Leucocrypta, containing the heterotrophic katablepharids.[135] The next year, a separate group of authors proposed a different higher ranking for katablepharids as a phylum Kathablepharida or Phylum Katablepharidophyta, related to but independent from phylum Cryptophyta, with no mention of Cryptista.[136] Between 2013 and 2015, Cavalier-Smith updated the classification once more by describing three new subphyla: Rollomonadia, containing the previous subphyla lowered to superclasses; Palpitia, containing the flagellate Palpitomonas bilix;[137] and Corbihelia, containing picozoans, telonemids, and some heliozoan species (Heliomorpha and Microheliella).[138] Corbihelia did not reach consensus: later analyses and revisions separated telonemids and picozoans as their own clades, and placed Heliomorpha in Cercozoa.[6] However, the addition of Palpitomonas and the monophyly of Rollomonadia have been supported in other analyses.[131]

Cryptista was redefined in the 2019 ISOP revision as the clade containing Palpitomonas, katablepharids, goniomonads and cryptomonads. However, this revision introduced yet another classification system that is contradictory with the previous ones. They proposed a single class Cryptophyceae uniting cryptomonads, goniomonads and katablepharids, and treated cryptomonads as a single order Cryptomonadales,[6] although this does not follow scientific consensus: there are more cryptomonad orders (e.g., Pyrenomonadales, Tetragonidiales) and the name Cryptophyceae was already used for taxa that excluded katablepharids[139] and often excluded goniomonads too.[138] There has not been a new revision since.

Unlike with Heliomorpha, the genus Microheliella was genetically sequenced and its affinities have been resolved. In 2022, it was proposed as the sister group of Cryptista, in a clade known as Pancryptista.[132]

Pancryptista Yazaki et al. 2022

Haptista

  • Haptophyta Hibberd 1976 ex. Edvardsen & Eikrem 2000
  • Class Centroplasthelida Febvre-Chevalier & Febvre 1984 (=Centrohelea Kühn 1926 sensu Cavalier-Smith in Yabuki et al. 2012; Centroheliozoa Dürrschmidt & Patterson 1987).[145] Genera incertae sedis: Meringosphaera,[146] Parasphaerastrum.
    • Family Spiculophryidae Shɨshkin & Zlatogursky 2018, genus Spiculophrys.
    • Superorder Pterocystida Cavalier-Smith and von der Heyden 2007, emend. Shɨshkin and Zlatogursky 2018
      • Order Raphidista Shɨshkin & Zlatogursky 2018
        • Family Choanocystidae Cavalier-Smith & von der Heyden 2007, genus Choanocystis.
        • Family Raphidiophryidae Febvre-Chevalier & Febvre 1984, emend. Shɨshkin & Zlatogursky 2018, genus Raphidiophrys.
      • Order Pterista Shɨshkin & Zlatogursky 2018
        • Family Oxnerellidae Cavalier-Smith & Chao 2012, genus Oxnerella.
        • Family Pterocystidae Cavalier-Smith & von der Heyden 2007, genera Pterocystis, Raineriophrys, Chlamydaster, Pseudoraphidiophrys, Pseudoraphidocystis, Triangulopteris,[147] Khitsovia.[148]
        • Family Heterophryidae Poche 1913, emend. Cavalier-Smith & von der Heyden 2007, genera Heterophrys, Sphaerastrum.
        • Family Clypiferidae Shɨshkin in Shɨshkin et al. 2021, genus Clypifer.[145]
    • Superorder Panacanthocystida Shɨshkin & Zlatogursky 2018
      • Order Chthonida Shɨshkin & Zlatogursky 2018, suborder Yogsothothina Shɨshkin & Zlatogursky 2018, family Yogsothothidae Shɨshkin & Zlatogursky 2018, genera Yogsothoth, Pinjata.[149]
      • Order Acanthocystida Cavalier-Smith & von der Heyden 2007 emend. Shɨshkin & Zlatogursky 2018
        • Suborder Marophryina Cavalier-Smith in Yabuki et al. 2012, family Marophryidae Cavalier-Smith & von der Heyden 2007 emend. Shɨshkin & Zlatogursky 2018, genus Marophrys.
        • Suborder Chalarothoracina Hertwig & Lesser 1874 sensu Cavalier-Smith in Yabuki et al. 2012 emend. Shɨshkin & Zlatogursky 2018
          • Family Acanthocystidae Claus 1874 emend. Shɨshkin & Zlatogursky 2018, genus Acanthocystis.
          • Family Raphidocystidae Zlatogursky 2018, genus Raphidocystis.

Stramenopiles

  • Class Platysulcea Cavalier-Smith 2018 → order Platysulcida Cavalier-Smith 2018 → family Platysulcidae Shiratori, Nakayama & Ishida 2015. Sole genus: Platysulcus Shiratori, Nakayama & Ishida 2015.[clarification needed]

Bigyra

Bigyra was initially proposed as a phylum of heterotrophic protists closely related to the photosynthetic heterokonts (Ochrophyta). It contained three subphyla: Pseudofungi (oomycetes and hyphochytrids), Bigyromonada (free-living biflagellates), and Opalinata (large multi-flagellated gut symbionts). The phylum was proposed with a unifying characteristic, the presence of a flagellar transition zone with double helices or rings. This definition was later modified to exclude both Pseudofungi and Bigyromonada, and it was instead reduced to two different subphyla: Opalozoa (including Opalinata and bicosoecids) and Sagenista. Prior to this, Sagenista itself was also a phylum containing bicosoecids and labyrinthuleans, but it got reduced to only labyrinthuleans and a few flagellates.[150][3]

The current definition of Bigyra is paraphyletic according to some phylogenetic analyses, with Sagenista more closely related to Gyrista. Despite its probable paraphyly, most taxonomists continue to use it, and it was recognized in the 2019 revision by the ISOP, which prioritizes monophyletic taxa.[6][151] Its global classification was last revised by Cavalier-Smith in 2013 and 2018,[7][3] while the specific class Placididea was revised in 2021, with new taxa described by Alexandra Rybarski and coauthors,[152] and the classes Labyrinthulea and Opalinea were revised in-depth in the 2017 Handbook of the protists.[153][154]

Phylum Bigyra(P?) Cavalier-Smith 1998 emend. 2013

  • Subphylum Opalozoa Cavalier Smith 1991 emend. 2006
    • Infraphylum Placidozoa Cavalier-Smith 2013
      • Superclass Wobblata(P) Cavalier-Smith in Cavalier-Smith and Chao, 2006 stat. n. 2013
        • Class Placididea Moriya, Nakayama & Inouye 2002, order Placidida Moriya, Nakayama & Inouye 2002, family Placididae Moriya, Nakayama & Inouye 2002, genera Allegra, Haloplacidia, Pendulomonas, Placidia, Placilonga, Suigetsumonas, Wobblia.
        • Class Nanomonadea Cavalier-Smith in Cavalier-Smith & Scoble 2013 (=clade MAST-3), order Uniciliatida Cavalier-Smith in Cavalier-Smith & Scoble 2013
          • Family Incisomonadidae Cavalier-Smith in Cavalier-Smith & Scoble 2013, genus Incisomonas.
          • Family Solenicolidae Cavalier-Smith in Cavalier-Smith & Scoble 2013, genus Solenicola.
        • Class Opalomonadea Cavalier-Smith 2013 (=clade MAST-12), no described species.
      • Superclass Opalinata Wenyon 1926 emend. Cavalier-Smith 1997
    • Infraphylum Bikosia Cavalier-Smith 2018 (=Bicosoecida Grassé 1926 emend. Karpov 1998), class Bikosea Cavalier-Smith 1986 as "Bicosoecea" orth. emend. 2013.
      • Family Pseudobodonidae Cavalier-Smith in Cavalier-Smith & Scoble 2013, genus Pseudobodo.
      • Subclass Bicosidia(P?)[155] Cavalier-Smith in Cavalier-Smith & Chao 2006. Genera not assigned to any order: Halocafeteria,[156] Cafileria.[157][158][7]
        • Order Borokales (Borokida) Cavalier-Smith in Cavalier-Smith & Chao 2006, family Borokaceae (Borokida) Cavalier-Smith in Cavalier-Smith & Chao 2006, genus Boroka.
        • Order Anoecales(P?) (Anoecida) Cavalier-Smith 1997[k] Genus not assigned to any lower taxon: Bilabrum.[159]
          • Family Anoecaceae Cavalier-Smith in Cavalier-Smith & Chao 2006, genus Anoeca.
          • Family Caecitellaceae (Caecitellidae) Cavalier-Smith in Cavalier-Smith & Chao 2006, genus Caecitellus.
          • Family Cafeteriaceae (Cafeteriidae) Moestrup 1995, genus Cafeteria.
          • Family Symbiomonadaceae Cavalier-Smith in Cavalier-Smith & Chao 2006, genus Symbiomonas.
        • Order Bicoecida (Bicoecales) Grassé 1926
          • Family Bicosoecidae (Bicosoecaceae) Stein 1878, genera Bicosoeca, Stephanocodon, Poteriodendron, Hirugamonas.[158]
          • Family Labromonadidae (Labromonadaceae) Cavalier-Smith in Cavalier-Smith & Chao 2006, genus Labromonas.
        • Order Pseudodendromonadida ("Pseudodendromonadales") Hibberd 1985 emend. Cavalier-Smith 2006.
          • Family Pseudodendromonadidae ("Pseudodendromonadaceae") Karpov 2000, genera Cyathobodo, Pseudodendromonas.
          • Family Siluaniidae(P) (Siluaniaceae) Karpov 1998, genera Adriamonas, Siluania, Otto, Regin.[160]
          • Family Paramonadidae Kent 1880, genus Paramonas.
          • Family Nanidae Cavalier-Smith in Cavalier-Smith & Scoble 2013, genus Nanum (="Nanos").
          • Family Neradidae Cavalier-Smith in Cavalier-Smith & Chao 2006, genus Nerada.
          • Family Filidae Cavalier-Smith in Cavalier-Smith & Scoble 2013, genus Filos.
      • Infraphylum incertae sedis
        • Order Rictida Cavalier-Smith in Cavalier-Smith & Scoble 2013, family Rictidae Cavalier-Smith in Cavalier-Smith & Scoble 2013, genus Rictus.
        • Cantina Yubuki et al. 2015
  • Subphylum Sagenista Cavalier-Smith 1995
    • Class Labyrinthulea L.S.Olive 1975 ex Cavalier-Smith 1989 (Labyrinthulomycetes Arx 1970 ex Dick 2001) (='phylum' Labyrinthomorpha Page in Levine et al. 1980 (Labyrinthulomycota Whittaker 1969))
      • Order Amphitremida (Poche 1913) Gomaa et al. 2013
        • Family Amphitremidae Poche 1913, genera Amphitrema, Archerella (="Ditrema"),[161] Paramphitrema.
        • Family Diplophryidae Cavalier-Smith in Anderson & Cavalier-Smith 2012, genus Diplophrys.
      • Order Amphifilida Cavalier-Smith in Anderson & Cavalier-Smith 2012 as "Amphifiloidea"
        • Family Amphifilidae Cavalier-Smith in Anderson & Cavalier-Smith 2012, genus Amphifila.
        • Family Sorodiplophryidae Cavalier-Smith in Anderson & Cavalier-Smith 2012, genera Fibrophrys, Sorodiplophrys.
      • Order Oblongichytrida (Oblongichytriales) Bennett et al. 2017, family Oblongichytriidae (Oblongichytriaceae) Cavalier-Smith in Anderson & Cavalier-Smith 2012, genus Oblongichytrium.
      • Order Labyrinthulida Doffein 1901 (Labyrinthulales E.A.Bessey 1950). Genus not assigned to any family: Stellarchytrium.
        • Family Aplanochytriidae (Aplanochytriaceae) Leander ex Cavalier-Smith in Anderson & Cavalier-Smith 2012, genus Aplanochytrium (=Labyrinthuloides).
        • Family Labyrinthulidae Cienkowski 1867 (Labyrinthulaceae Haeckel 1868), genus Labyrinthula (=Pseudoplasmodium, Labyrinthodictyon, Labyrinthorhiza).
      • Order Thraustochytrida (Thraustochytriales) Sparrow 1943
        • Family Althorniidae (Althornidiaceae) Jones & Alderman 1973, genus Althornia.
        • Family Thraustochytriidae (Thraustochytriaceae) Sparrow ex Cejp 1959, genera Aurantiochytrium, Botryochytrium, Japonochytrium, Monorhizochytrium, Parietichytrium, Phycophthorum,[162] Schizochytrium, Sicyoidochytrium, Thraustochytrium, Ulkenia.
    • Class Eogyrea Cavalier-Smith 2013, order Eogyrida Cavalier-Smith 2018[3] (=clade MAST-6). Genera not assigned to any lower taxon: Mastreximonas, Vomastromonas.[151]

Gyrista

  • Kaonashiidae Weston, Eglit & Simpson 2023. Kaonashia.[164][165]
  • Pseudofungi Cavalier-Smith 1986 (=Heterokontimycotina M.W. Dick 1976, Peronosporomycotina M.W.Dick 2001)[166]:288
    • Bigyromonadea Cavalier-Smith 1997
      • Developea Aleoshin et al. 2016. Cubaremonas Tikhonenkov, Cho, and Keeling 2022,[167] Develoamica Prokina et al. 2026,[168] Develocanicus Tikhonenkov, Cho, Mylnikov, and Keeling 2022,[167] Develocauda Tikhonenkov, Cho, and Keeling 2022,[167] Developarva Prokina et al. 2026,[168] Developayella Tong 1995, Develorapax Karpov & Aleoshin 2016, Mediocremonas del Campo and Weiler 2020.[169]
      • Pirsoniales Cavalier-Smith & Chao 2006 emend. Prokina et al. 2024. Genera not assigned to any lower taxon: Bordeauxia Prokina et al. 2024; Bullionia Prokina et al. 2024; Feodosia Prokina et al. 2024; Koktebelia Prokina et al. 2024.[170][171]
    • HyphochytriomycetesICN Sparrow ex M.W.Dick 1983 (HyphochytreaICZN Cavalier-Smith 1986). Genus not assigned to any lower taxon: Hyphochytrium Karling 1939.
      • Anisolpidiaceae Karling 1943 emend. Dick 2001. Anisolpidium Karling 1943; Canteriomyces Sparrow 1960.
      • Rhizidiomycetaceae Karling 1943. Latrostium Zopf 1894; Rhizidiomyces Zopf 1884; Rhizidiomycopsis Sparrow 1960.
    • Peronosporomycetes Dick 2001 (=Peronosporomycetes Winter 1897, emend. Dick 1976). Incertae sedis: Atkinsiella Vishniac 1958; Ciliatomyces Foissner & Foissner 1995 (=Ciliomyces Foissner & Foissner 1986);[172] Crypticola Humber et al. 1989; Ectrogella Zopf 1884; Eurychasma Magnus 1905; Halodaphnea M.W.Dick 1998; Haliphthoros Vishniac 1958; Haptoglossa Drechsler 1940; Lagena Vanterp. & Ledingham 1930; Lagenisma Drebes 1968; Olpidiopsis Cornu 1872; Pontisma H.E. Petersen 1905; Pythiella Couch 1935; Rozellopsis Karling 1942; Sirolpidium H.E.Petersen 1905.
  • Ochrophyta Cavalier-Smith 1986, emend. Cavalier-Smith & Chao 1996 (=Heterokontophyta Guiry, R.A.Andersen & Moestrup 2023)

Alveolata

Loeffela

Cladogram of Alveolata, based on a SSU rDNA phylogeny of basal alveolates[188] and a 203-gene phylogeny of apicomplexans and their relatives[189] published in 2023.

Genera not assigned to any lower taxon: Neocolponema Gigeroff et al. 2023, Loeffela Gigeroff et al. 2023.[188]

  • Phylum[n] Colponemidia Tikhonenkov et al. 2014 → class Colponemea Cavalier-Smith 1993, emend. Tikhonenkov et al. 2014 → order Colponemida Cavalier-Smith 1993 → family Colponemidae Cavalier-Smith & Chao 2004, genus Colponema Stein 1878.
  • Phylum[n] Acavomonidia Tikhonenkov et al. 2014 → class Acavomonea Tikhonenkov et al. 2014 → order Acavomonadida Tikhonenkov et al. 2014 → family Acavomonadidae Tikhonenkov et al. 2014, genus Acavomonas Tikhonenkov et al. 2014.
  • Order Palustrimonadida Cavalier-Smith 2018 → family Palustrimonadidae Cavalier-Smith 2018, genus Palustrimonas Patterson & Simpson 1996.

Myzozoa

ACS

Dinozoa

  • Perkinsea Levine 1978. Incertae sedis genera: Phagodinium Kristiansen 1993; Rastrimonas Brugerolle 2003;[p] Acrocoelus Fernández, Pardos, Benito & Arroyo 1999.
    • Maranthos Alacid & Reñé 2021[202]
    • Pararosariidae Jeon & Park 2021. Sole genus: Pararosarium Jeon & Park 2021.[203]
    • Parviluciferaceae Reñé & Alacid 2017. Genera: Dinovorax Reñé & Alacid 2017; Parvilucifera Norén & Moestrup 1999; Snorkelia Reñé & Alacid 2017;[204] Tuberlatum Jeon & Park 2019.[205]
    • Perkinsidae Levine 1978. Sole genus: Perkinsus Levine 1978.
    • Xcellidae Freeman, Fuss, Kristmundsson, Keeling, Shalchian-Tabrizi & Bass 2017 em. Karlsbakk, Nystøyl, Plarre & Nylund 2021. Genera: Cryoxcellia Evans, Patel, Matzke & Millar 2023,[206] Gadixcellia Freeman, Fuss, Kristmundsson, Keeling, Shalchian-Tabrizi & Bass 2017; Notoxcellia Desvignes et al. 2022;[207] Salmoxcellia Karlsbakk, Nystøyl, Plarre & Nylund 2021;[208] Xcellia Freeman, Fuss, Kristmundsson, Keeling, Shalchian-Tabrizi & Bass 2017.
  • Dinoflagellata Bütschli 1885, emend. Fensome et al. 1993, emend. Adl et al. 2005. Incertae sedis genera: free-living (Adenoides, Akashiwo, Amphidiniella, Ankistrodinium, Apicoporus, Archaeosphaerodiniopsis, Bispinodinium, Bysmatrum, Cabra, Cladopyxis, Crypthecodinium, Cucumeridinium, Dactylodinium, Dicroerisma, Gloeodinium, Grammatodinium, Gynogonadinium, Gyrodiniellum, Halostylodinium, Heterodinium, Moestrupia, Paragymnodinium, Phytodinium, Plagiodinium, Planodinium, Pileidinium, Pseudadenoides, Pseudothecadinium, Pyramidodinium, Rhinodinium, Roscoffia, Sabulodinium, Sphaerodinium, Spiniferodinium, Testudodinium, Thecadinium, Thecadiniopsis, Togula) and parasitic Blastodiniales Chatton 1906 [no longer valid] (Amyloodinium, Apodinium, Cachonella, Caryotoma, Crepidoodinium, Haplozoon, Oodinium, Myxodinium, Piscinoodinium, Protoodinium, Rhinodinium, Schyzochitriodinium, Stylodinium).

Ciliophora

  • Postciliodesmatophora Gerassimova & Seravin 1976
  • Intramacronucleata Lynn 1996. Incertae sedis taxa: Protocruziidae Jankowski 1980 [Protocruziidia de Puytorac et al. 1987] (Protocruzia Faria da Cunha & Pinto 1922).
    • SAL Gentekaki et al. 2014. Incertae sedis taxa: Cariacotrichea Orsi et al. 2011 (Cariacothrix caudata), Mesodiniidae ankowski, 1980 (Mesodinium), Phacodiniidia Small and Lynn 1985 (Phacodinium).
      • Spirotrichea Bütschli 1889
        • Euplotia Jankowski 1979
          • Euplotida Small & Lynn 1985
            • Aspidiscidae Ehrenberg 1830. Aspidisca.
            • Certesiidae Borror & Hill 1995. Certesia.
            • Euplotidae Ehrenberg 1838. Euplotes.
            • Gastrocirrhidae Fauré-Fremiet 1961. Gastrocirrhus.
            • Uronychidae Jankowski 1975. Diophrys, Uronychia.
          • Discocephalida
            • Discocephalidae Jankowski 1979. Discocephalus, Prodiscocephalus, Paradiscocephalus.
            • Pseudoamphisiellidae Song et al. 1997. Leptoamphisiella, Pseudoamphisiella.
        • Perilemmaphora Berger 2008
          • Hypotrichia Stein 1859
            • Stichotrichida Fauré-Fremiet 1961(P)[r]
              • Amphisiellidae Jankowski 1979. Amphisiella, Bistichella.
              • Atractosidae Bourland 2015. Atractos.
              • Epiclintidae Wicklow & Borror 1990. Epiclintes.
              • Gonostomatidae Small & Lynn 1985. Cotterillia, Gonostomum.
              • Halteriidae Claparède & Lachmann 1858. Halteria, Meseres.
              • Holostichidae Fauré-Fremiet 1961. Holosticha, Uncinata.
              • Kahliellidae Tuffrau 1979. Deviata, Kahliella.
              • Keronidae Dujardin 1840. Kerona.
              • Oxytrichidae Ehrenberg 1830(P). Cyrtohymena, Gastrostyla, Oxytricha, Stylonychia.
              • Parabirojimidae Dai & Xu 2011. Parabirojimia, Tunicothrix.
              • Plagiotomidae Bütschli 1887. Plagiotoma.
              • Psammomitridae Jankowski 1979. Psammomitra.
              • Pseudoamphisiellidae Song et al. 1996. Pseudoamphisiella.
              • Psilotrichidae Bütschli 1889. Psilotricha, Urospinula.
              • Schmidingerotrichidae Foissner 2012. Schmidingerothrix.
              • Spirofilidae von Gelei 1929. Spirofilopsis, Strongylidium.
              • Trachelostylidae Small & Lynn 1985. Trachelostyla.
              • Uroleptidae Foissner & Stoeck 2008. Paruroleptus, Uroleptus.
            • Urostylida Jankowski 1979(P)
              • Bergeriellidae Liu et al. 2010. Bergeriella, Neourostylopsis.
              • Hemicycliostylidae Lyu et al. 2018. Australothrix, Hemicycliostyla.
              • Pseudokeronopsidae Borror & Wicklow, 1983. Apoholosticha, Pseudokeronopsis.
              • Pseudourostylidae Jankowski 1979. Pseudourostyla.
              • Urostylidae Bütschli 1889. Bakuella, Diaxonella, Urostyla.
          • Oligotrichea Bütschli 1887
            • Oligotrichida Bütschli 1887
              • Cyrtostrombidiidae Agatha 2004. Cyrtostrombidium.
              • Pelagostrombidiidae Agatha 2004. Pelagostrombidium.
              • Strombidiidae Fauré-Fremiet 1970. Strombidium(P).
              • Tontoniidae Agatha 2004. Laboea, Tontonia.
            • Choreotrichida Small & Lynn 1985. Incertae sedis taxa: Lynnella Liu et al. 2011 [Lynnellidae Liu et al. 2011; Lynnellida Liu et al. 2015]
              • Strobilidiina Jankowski 1980(P)
                • Leegaardiellidae Lynn & Montagnes 1988. Leegaardiella.
                • Lohmanniellidae Montagnes & Lynn 1991. Lohmanniella.
                • Strobilidiidae Kahl in Doflein & Reichenow 1929. Strobilidium.
                • Strombidinopsidae Small & Lynn 1985. Strombidinopsis(P).
              • Tintinnina Kofoid & Campbell 1929. Incertae sedis taxa: Helicostomella, Tintinnopsis(P), several other genera.
                • Ascampbelliellidae Corliss 1960. Ascampbelliella
                • Cyttarocylididae Kofoid & Campbell 1929 [probably synonymous with Petalotrichidae]. Cyttarocylis.
                • Dictyocystidae Haeckel 1873. Dictyocysta.
                • Epiplocylididae Kofoid & Campbell 1939. Epiplocylis.
                • Eutintinnidae Bachy et al. 2012. Dartintinnus, Eutintinnus.
                • Favellidae Kofoid & Campbell 1929. Favella.
                • Nolaclusiliidae Sniezek et al. 1991. Nolaclusilis.
                • Petalotrichidae Kofoid & Campbell 1929 [probably synonymous with Cyttarocylididae]. Petalotricha.
                • Ptychocylididae Kofoid & Campbell 1929. Cymatocylis, Ptychocylis.
                • Rhabdonellidae Kofoid & Campbell 1929. Metacylis, Rhabdonella, Schmidingerella.
                • Stenosemellidae Campbell 1954(P). Stenosemella.
                • Tintinnidae Claparède & Lachmann 1858. Amphorellopsis, Salpingacantha, Salpingella, Tintinnus.
                • Tintinnidiidae Kofoid & Campbell 1929. Tintinnidium.
                • Undellidae Kofoid & Campbell 1929. Undella.
                • Xystonellidae Kofoid & Campbell 1929. Dadayiella, Parafavella, Xystonella.
        • Licnophoridae Bütschli 1887. Licnophora, Prolicnophora.
        • Kiitrichidae Nozawa 1941. Caryotricha, Kiitricha.
      • Lamellicorticata Vd'ačný et al. 2010
        • Armophorea Lynn 2004. Incertae sedis taxa: Mylestomatidae Kahl in Doflein & Reichenow, 1929 (Mylestoma).
          • Metopida Jankowski 1980(P)
            • Metopidae Kahl 1927(P). Bothrostoma, Brachonella, Eometopus, Metopus, Parametopidium, Tesnospira.
            • Apometopidae Foissner 2016. Cirranter, Urostomides.
            • Tropidoatractidae Rotterová et al. 2018. Palmarella, Tropidoatractus.
          • Clevelandellida de Puytorac & Grain 1976
            • Clevelandellidae Kidder 1938. Clevelandella.
            • Inferostomatidae Ky 1971. Inferostoma.
            • Neonyctotheridae Affa'a 1987. Neonyctotherus.
            • Nyctotheridae Amaro 1972(P). Nyctotherus.
            • Sicuophoridae Amaro 1972. Sicuophora.
          • Caenomorphidae Poche 1913. Caenomorpha, Ludio, Sulfonecta.
          • Odontostomatida Sawaya 1940
            • Discomorphellidae Corliss 1960. Discomorphella.
            • Epalxellidae Corliss 1960. Epalxella, Saprodinium.
        • Litostomatea Small & Lynn 1981
          • Rhynchostomatia Jankowski 1980
            • Dileptida Jankowski 1978
              • Dileptidae Jankowski 1980. Apodileptus, Dileptus, Pseudomonilicaryon.
              • Dimacrocaryonidae Jankowski 1978. Dimacrocaryon, Monomacrocaryon, Rimaleptus.
              • Tracheliidae Ehrenberg 1838. Trachelius.
          • Haptoria Corliss 1974(P). Incertae sedis taxa: Chaenea.
            • Lacrymariidae de Fromentel 1876. Lacrymaria.
            • Haptorida Corliss 1974
              • Enchelyodonidae Foissner et al. 2002. Enchelyodon, Fuscheria.
              • Homalozoonidae Jankowski 1980. Homalozoon.
              • Pleuroplitidae Foissner 1996. Pleuroplites.
            • Didiniidae Poche 1913. Didinium, Monodinium.
            • Pleurostomatida Schewiakoff 1896
              • Amphileptidae Bütschli 1889. Amphileptus.
              • Litonotidae Kent 1882. Litonotus.
              • Kentrophyllidae Wu et al. 2015. Epiphyllum, Kentrophyllum.
            • Spathidiida Foissner & Foissner 1988
              • Acropisthiidae Foissner & Foissner 1988. Acropisthium, Chaenea.
              • Actinobolinidae Kahl 1930. Actinobolina.
              • Apertospathulidae Foissner et al. 2005. Apertospathula.
              • Enchelyidae Ehrenberg 1838. Enchelys.
              • Pseudoholophryidae Berger et al. 1984. Pseudoholophrya.
              • Spathidiidae Kahl in Doflein & Reichenow 1929. Legendrea,[215] Spathidium.
              • Trachelophyllidae Kent 1882. Trachelophyllum.
            • Helicoprorodontidae Small & Lynn 1985
          • Trichostomatia Bütschli 1889
            • Vestibuliferida de Puytorac et al. 1974
              • Balantidiidae Reichenow in Doflein and Reichenow 1929. Balantidium, Neobalantidium(P).
              • Buetschliidae Poche 1913. Buetschlia.
              • Paraisotrichidae da Cunha 1917. Paraisotrichia.
              • Protocaviellidae Grain in Corliss 1979. Protocaviella.
              • Protohalliidae da Cunha & Muniz 1927. Protohallia.
              • Pycnotrichidae Poche 1913. Pycnothrix, perhaps Buxtonella.
          • Isoendo
            • Isotrichidae Bütschli 1889. Dasytricha, Isotricha.
            • Entodiniomorphida Reichenow in Doflein & Reichenow 1929
              • Blepharocorythina Wolska 1971
                • Blepharocorythidae Hsiung 1929. Blepharocorys.
                • Parentodiniidae Ito, Miyazaki & Imai 2002. Parentodinium.
                • Pseudoentodiniidae Wolska 1986. Pseudoentodinium.
              • Entodiniomorphina Reichenow in Doflein & Reichenow 1929
                • Cycloposthiidae Poche 1913. Cycloposthium.
                • Gilchristinidae Ito, Ishihara & Imai 2014 [Gilchristidae Ito et al. 2006]. Digilchristia, Gilchristina.[216]
                • Ophryoscolecidae Stein 1859. Entodinium, Ophryoscolex, Polyplastron.
                • Polydiniellidae Corliss 1960. Polydiniella.
                • Rhinozetidae Van Hoven, Gilchrist & Hamilton-Attwell 1988. Rhinozeta.
                • Spirodiniidae Strelkow 1939. Spirodinium.
                • Telamodiniidae Latteur & Dufey 1967. Telamodinium.
                • Troglodytellidae Corliss 1979. Troglodytella,.
            • Macropodiniida Lynn 2008
              • Amylovoracidae Cameron & O'Donoghue 2002. Amylovorax.
              • Macropodiniidae Dehority 1996. Macropodinium.
              • Polycostidae Cameron & O'Donoghue 2003. Polycosta.
    • CONTHREEP Lynn in Adl et al. 2012 [Ventrata Cavalier-Smith 2004]. Incertae sedis taxa: Askenasia Blochmann 1895, Cyclotrichiidae Jankowski 1980 (Cyclotrichium), Paraspathidium Noland 1937, Pseudotrachelocercidae Song 1990 (Pseudotrachelocerca), Discotrichidae Jankowski 1967 [Discotrichida Fan et al. 2014] (Discotricha, Lopezoterenia).
      • Phyllopharyngea de Puytorac et al. 1974
        • Synhymeniida de Puytorac et al. in Deroux 1978
          • Nassulopsidae Deroux in Corliss 1979. Nassulopsis.
          • Orthodonellidae Jankowski 1968. Orthodonella, Zosterodasys.
          • Scaphidiodontidae Deroux in Corliss 1979. Chilodontopsis, Scaphidiodon.
          • Synhymeniidae Jankowski in Small & Lynn 1985. Synhymenia.
        • Subkinetalia Gong et al. 2009
          • Cyrtophoria Fauré-Fremiet in Corliss 1956
            • Chlamydodontida Deroux 1976(P)
              • Chilodonellidae Deroux 1970. Chilodonella.
              • Chitonellidae Small & Lynn 1985. Chitonella.
              • Chlamydodontidae Stein 1859. Chlamydodon.
              • Gastronautidae Deroux 1994. Gastronauta.
              • Kryoprorodontidae Alekperov & Mamajeva 1992. Gymnozoum.
              • Lynchellidae Jankowski 1968. Chlamydonella, Lynchella.
            • Dysteriida Deroux 1976
              • Dysteriidae Claparède & Lachmann 1858. Dysteria(P), Trochilia.
              • Hartmannulidae Poche 1913(P). Hartmannula.
              • Kyaroikeidae Sniezek & Coats 1996. Kyaroikeus.
              • Plesiotrichopidae Deroux 1976. Plesiotrichopus.
              • Chonotrichia Wallengren 1895
                • Exogemmida Jankowski 1972
                  • Chilodochonidae Wallengren 1895. Chilodochona.
                  • Filichonidae Jankowski 1973. Filichona.
                  • Helichonidae Jankowski 1972. Heliochona.
                  • Lobochonidae Jankowski 1967. Lobochona.
                  • Phyllochonidae Jankowski 1972. Phyllochona.
                  • Spirochonidae Stein 1854. Spirochona.
                • Cryptogemmida Jankowski 1975
                  • Actinichonidae Jankowski 1973. Actinichona.
                  • Echinichonidae Jankowski 1973. Echinichona.
                  • Inversochonidae Jankowski 1973. Inversochona.
                  • Isochonidae Jankowski 1973. Isochona.
                  • Isochonopsidae Batisse & Crumeyrolle 1988. Isochonopsis.
                  • Stylochonidae Mohr 1948. Stylochona.
          • Rhynchodia Chatton & Lwoff 1939
            • Hypocomidae Bütschli 1889. Hypocoma.
            • Rhynchodida Chatton & Lwoff 1939
              • Ancistrocomidae Chatton & Lwoff 1939. Ancistrocoma.
              • Sphenophryidae Chatton & Lwoff 1921. Sphenophrya.
          • Suctoria Claparède & Lachmann 1858
            • Exogenida Collin 1912
              • Allantosomatidae Jankowski 1967. Allantosoma.
              • Dentacinetidae Batisse 1992. Dentacineta.
              • Dendrosomididae Jankowski 1978. Dendrosomides.
              • Ephelotidae Kent 1882. Ephelota.
              • Lecanophryidae Jankowski 1973. Lecanophrya.
              • Manuelophryidae Dovgal 2002. Manuelophrya.
              • Metacinetidae Bütschli 1889. Metacineta.
              • Ophryodendridae Stein 1867. Ophryodendron.
              • Paracinetidae Jankowski 1978. Paracineta.
              • Phalacrocleptidae Kozloff 1966. Phalacrocleptes.
              • Podophryidae Haeckel 1866. Podophrya.
              • Praethecacinetidae Dovgal 1996. Praethecacineta.
              • Rhabdophryidae Jankowski 1970. Rhabdophrya.
              • Severonidae Jankowski 1981. Severonis.
              • Spelaeophryidae Jankowski in Batisse 1975. Spelaeophrya.
              • Tachyblastonidae Grell 1950. Tachyblaston.
              • Thecacinetidae Matthes 1956. Thecacineta.
            • Endogenida Collin 1912
              • Acinetidae Stein 1859. Acineta.
              • Acinetopsidae Jankowski 1978. Acinetopsis.
              • Choanophryidae Dovgal 2002. Choanophrya.
              • Corynophryidae Jankowski 1981. Corynophrya.
              • Dactylostomatidae Jankowski 1978. Dactylostoma.
              • Dendrosomatidae Fraipont 1878. Dendrosoma.
              • Endosphaeridae Jankowski in Corliss 1979. Endosphaera.
              • Erastophryidae Jankowski 1978. Erastophrya.
              • Pseudogemmidae Jankowski 1978. Pseudogemma.
              • Rhynchetidae Jankowski 1978. Rhyncheta.
              • Solenophryidae Jankowski 1981. Solenophrya.
              • Tokophryidae Jankowski in Small & Lynn 1985. Tokophrya.
              • Trichophryidae Fraipont 1878. Trichophrya.
            • Evaginogenida Jankowski in Corliss 1979
              • Cometodendridae Jankowski 1978. Cometodendron.
              • Cyathodiniidae da Cuhna 1914. Cyathodinium.
              • Dendrocometidae Haeckel 1866. Dendrocometes.
              • Discophryidae Collin 1912. Discophrya.
              • Enchelyomorphidae Augustin & Foissner 1992. Enchelyomorpha.
              • Heliophryidae Corliss 1979. Heliophrya.
              • Periacinetidae Jankowski 1978. Periacineta.
              • Prodiscophryidae Jankowski 1978. Prodiscophrya.
              • Rhynchophryidae Jankowski 1978. Rhynchophrya.
              • Stylocometidae Jankowski 1978. Stylocometes.
              • Trypanococcidae Dovgal 2002. Trypanococcus.
      • Colpodea Small & Lynn 1981
        • Bursariomorphida Fernández-Galiano 1978
          • Bryometopidae Jankowski 1980. Bryometopus(P), Thylakidium.
          • Bursaridiidae Foissner 1993. Bursaridium, Paracondylostoma.
          • Bursariidae Bory de St. Vincent 1826. Bursaria.
        • Colpodida de Puytorac et al. 1974. Incertae sedis taxa: Bardeliellidae Foissner 1984 (Bardeliella), Hausmanniellidae Foissner 1987 (Avestina, Hausmanniella), Ilsiellidae Bourland et al. 2011 (Ilsiella), Pseudochlamydonellidae Buitkamp et al. 1989 (Hackenbergia, Pseudochlamydonella) and Marynidae Poche 1913 (Maryna).
          • Bryophryina de Puytorac et al. 1979
            • Bryophryidae de Puytorac et al. 1979. Bryophrya.
            • Sandmanniellidae Foissner & Stoeck 2009. Sandmanniella.
          • Colpodina Foissner et al. 2011
            • Colpodidae Bory de St. Vincent 1826(P). Colpoda.
            • Grandoriidae Corliss 1960. Grandoria.
            • Tillinidae Foissner et al. 2011. Tillina.
          • Grossglockneriidae Foissner 1980 [Grossglockneriina Foissner 1980]. Grossglockneria, Pseudoplatyophrya.
        • Cyrtolophosidida Foissner 1978
          • Cyrtolophosididae Stokes 1888. Cyrtolophosis.
          • Kreyellidae Foissner 1979. Kreyella.
        • Platyophryida de Puytorac et al. 1979
          • Ottowphryidae Foissner et al. 2011. Ottowphrya, Platyophryides.
          • Platyophryidae de Puytorac et al. 1979(P). Platyophrya.
          • Sagittariidae Grandori & Grandori 1935. Sagittaria.
          • Sorogenidae Bradbury & Olive 1980. Sorogena.
          • Woodruffiidae Gelei 1954. Etoschophrya, Rostrophrya, Woodruffia.
      • Nassophorea(P)
        • Colpodidiidae Foissner 1995. Colpodidium.
        • Nassulida Jankowski 1967
          • Furgasoniidae Corliss 1979. Furgasonia, Wolfkosia.
          • Nassulidae de Fromentel 1874. Nassula, Obertrumia.
        • Microthoracida Jankowski 1967
          • Microthoracidae Wrzesniowski 1870. Drepanomonas, Microthorax.
          • Leptopharyngidae Kahl 1926. Leptopharynx, Pseudomicrothorax.
      • Prostomatea Schewiakoff 1896(P)
        • Apsiktratidae Foissner et al. 1994 [Prostomatida Schewiakoff 1896]
          • Balanionidae Small & Lynn 1985. Balanion.
          • Cryptocaryonidae Wright & Colorni 2002. Cryptocaryon.
          • Colepidae Ehrenberg 1838. Coleps, Plagiopogon.
          • Holophryidae Perty 1852. Holophrya.
          • Lagynidae Sola et al. 1990. Lagynus.
          • Metacystidae Kahl 1926. Metacystis, Vasicola.
          • Placidae Small & Lynn 1985. Placus.
          • Plagiocampidae Kahl 1926. Plagiocampa.
          • Prorodontidae Kent 1881. Prorodon.
          • Urotrichidae Small & Lynn 1985. Urotricha.
      • Plagiopylea Small & Lynn 1985
        • Plagiopylida Small & Lynn 1985
          • Epalxellidae Corliss 1960. Epalxella, Saprodinium.
          • Plagiopylidae Schewiakoff 1896. Plagiopyla.
          • Sonderiidae Small & Lynn 1985. Sonderia.
          • Trimyemidae Kahl 1933. Trimyema.
      • Oligohymenophorea de Puytorac et al. 1974
        • Apostomatia Chatton & Lwoff 1928
          • Apostomatida Chatton & Lwoff 1928
          • Astomatophorida Jankowski 1966
            • Opalinopsidae Hartog 1906. Opalinopsis.
          • Pilisuctorida Jankowski 1966
            • Conidophryidae Kirby 1941. Conidophrys.
        • Astomatia Schewiakoff 1896
          • Anoplophryidae Cépède 1910. Anoplophrya.
          • Buetschliellidae de Puytorac in Corliss 1979. Buetschliella.
          • Clausilocolidae de Puytorac in Corliss 1979. Clausilocola.
          • Contophryidae de Puytorac 1972. Contophyra.
          • Haptophryidae Cépède 1923. Haptophrya.
          • Hoplitophryidae Cheissin 1930. Hoplitophrya.
          • Intoshellinidae Cépède 1910. Intoshellina.
          • Maupasellidae Cépède 1910. Maupasella.
          • Radiophryidae de Puytorac 1972. Radiophrya.
        • Hymenostomatia Delage & Hérouard 1896
          • Tetrahymenida Fauré-Fremiet in Corliss 1956. Incertae sedis taxa: Trichospiridae Kahl 1926 (Trichospira).
            • Curimostomatidae Jankowski 1968. Curimostoma.
            • Glaucomidae Corliss 1971. Glaucoma.
            • Spirozonidae Kahl 1926. Spirozona.
            • Tetrahymenidae Corliss 1952. Tetrahymena.
            • Turaniellidae Didier 1971. Colpidium, Dexiostoma, Turaniella.
          • Ophryoglenida Canella 1964
            • Ichthyophthiriidae Kent 1881. Ichthyophthirius.
            • Ophryoglenidae Kent 1881. Ophryoglena.
        • Peniculia Fauré-Fremiet in Corliss 1956(P)
          • Peniculida Fauré-Fremiet in Corliss 1956
            • Clathrostomatidae Kahl 1926. Clathrostoma.
            • Frontoniidae Kahl 1926. Disematostoma, Frontonia(P).
            • Lembadionidae Jankowski in Corliss 1979. Lembadion.
            • Maritujidae Jankowski in Small & Lynn 1985. Marituja.
            • Neobursaridiidae Dragesco & Tuffrau 1967. Neobursaridium.
            • Parameciidae Dujardin 1840. Paramecium.
            • Paranassulidae Fauré-Fremiet 1962. Paranassula.
            • Stokesiidae Roque 1961. Stokesia.
            • Urocentridae Claparède & Lachmann 1858 [Urocentrida de Puytorac, Grain & Mignot 1987]
        • Peritrichia Stein 1859
          • Sessilida Kahl 1933
            • Astylozoidae Kahl 1935. Astylozoon, Hastatella.
            • Ellobiophryidae Chatton and Lwoff 1929. Ellobiophrya.
            • Epistylididae Kahl 1933. Epistylis.
            • Lagenophryidae Bütschli 1889. Lagenophrys.
            • Operculariidae Fauré-Fremiet in Corliss 1979. Opercularia.
            • Rovinjellidae Matthes 1972. Rovinjella.
            • Scyphidiidae Kahl 1933(P). Scyphidia.
            • Termitophryidae Lom in Corliss 1979. Termitophrya.
            • Usconophryidae Clamp 1991. Usconophrys.
            • Vaginicolidae de Fromentel 1874. Cothurnia, Pyxicola, Thuricola, Vaginicola.
            • Vorticellidae Ehrenberg 1838. Carchesium, Epicarchesium(P), Ophrydium, Pelagovorticella, Pseudovorticella(P), Vorticella(P).
            • Zoothamniidae Sommer 1951. Haplocaulus, Zoothamnium.
          • Mobilida Kahl 1933
            • Polycyclidae Poljansky 1951. Polycycla.
            • Trichodinidae Claus 1874. Trichodina.
            • Trichodinopsidae Kent 1881. Trichodinopsis.
            • Urceolariidae Dujardin 1840. Leiotrocha, Urceolaria.
        • Scuticociliatia Small 1967(P)
          • Philasterida Small 1967
            • Cohnilembidae Kahl 1933. Cohnilembus.
            • Cryptochilidae Berger in Corliss 1979. Cryptochilum.
            • Entodiscidae Jankowski 1973. Entodiscus.
            • Entorhipidiidae Madsen 1931. Entorhipidium.
            • Orchitophryidae Cépède 1910(P). Orchitophrya.
            • Paralembidae Corliss & de Puytorac in Small & Lynn 1985. Anophrys, Paralembus.
            • Parauronematidae Small & Lynn 1985(P). Parauronema(P).
            • Philasteridae Kahl 1931. Kahlilembus, Philaster.
            • Pseudocohnilembidae Evans & Thompson 1964. Pseudocohnilembus.
            • Schizocaryidae Jankowski 1979. Schizocaryum.
            • Thigmophryidae Chatton & Lwoff 1926. Thigmophrya.
            • Thyrophylacidae Berger in Corliss 1961. Thyrophylax.
            • Uronematidae Thompson 1964. Uronema.
            • Urozonidae Grolière 1975. Urozona.
          • Pleuronematida Fauré-Fremiet in Corliss 1956
            • Calyptotrichidae Small & Lynn 1985. Calyptotricha.
            • Conchophthiridae Kahl in Doflein and Reichenow 1929. Conchophthirus.
            • Ctedoctematidae Small & Lynn 1985. Ctedoctema.
            • Cyclidiidae Ehrenberg 1838(P). Cristigera, Cyclidium.
            • Dragescoidae Jankowski 1980. Dragescoa.
            • Eurystomatellidae Miao et al. 2010. Eurystomatella.
            • Histiobalantiidae de Puytorac & Corliss in Corliss 1979. Histiobalantium.
            • Peniculistomatidae Fenchel 1965. Peniculistoma.
            • Pleuronematidae Kent 1881(P). Pleuronema.
            • Thigmocomidae Kazubski 1958. Thigmocoma.
          • Thigmotrichida Chatton & Lwoff 1922
            • Ancistridae Issel 1903. Ancistrum.
            • Hemispeiridae König 1894. Hemispeira.
            • Hysterocinetidae Diesing 1866. Hysterocineta.
            • Paraptychostomidae Ngassam et al. 1994. Paraptychostomum.
          • Loxocephalida Jankowski 1964(P)
            • Cinetochilidae Perty 1852(P). Cinetochilum, Sathrophilus.
            • Loxocephalidae Jankowski 1964. Cardiostomatella, Dexiotricha, Loxocephalus.

Rhizaria

  • Incertae sedis taxa: Gymnosphaerida Poche 1913, emend. Mikrjukov 2000. Actinocoryne, Cienkowskya, Gymnosphaera, Hedraiophrys [possible synonym of Cienkowskya], Wagnerella.
Cladogram of Rhizaria based on a 2019 phylogenomic analysis.[217]

Rhizaria is a clade that contains a wide variety of primarily amoeboid protists with fine (filose) pseudopodia. It is generally divided into two phyla: Cercozoa, which is composed of a heterogeneous mixture of free-living flagellates, testate amoebae, obligate intracellular parasites, and photosynthetic amoebae, among others; and Retaria, which includes the radiolarians and forams, two groups that have a rich and continuous fossil record over 500 million years long. Discovered only through molecular phylogenetics,[218] Rhizaria is home to over 11,000 described species.[219]

Cercozoa

Cladogram of Cercozoa based on a 2026 phylogenomic analysis.[220]

Cercozoa is a phylum of protists with extreme morphological diversity, ranging from small flagellates and amoeboflagellates, to testate amoebae, heliozoan- and radiolarian-like amoebae, and massive biomineralizing predators, as well as a few photosynthetic species. They are present abundantly in aquatic habitats and soils.[220] Cercozoa contains two subphyla: Filosa, represented primarily by free-living lineages, and Endomyxa, which includes obligate intracellular parasites and free-living predators.[221][s] Included in or related to Endomyxa are several clades known primarily from environmental sequences ('novel clades' 10, 11, 12),[222] with only a few members formally described.[220]

The classification below is based largely on the 2019 revision by Adl et al.[6] and Cavalier-Smith et al.[8] Adl et al. excludes Endomyxa and Skiomonadea from Cercozoa, but later works generally include them.[221][220]

Phylum Cercozoa Cavalier-Smith 1998, emend. Adl et al. 2005

  • Incertae sedis:
  • Order Tremulida[224][217] Cavalier-Smith & Howe in Howe et al. 2011, family Tremulidae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genus Tremula.
  • Order Aquavolonida[217] Bass & Berney in Bass et al. 2018, genera Aquavolon, Lapot.
  • Subphylum Filosa Cavalier-Smith in Cavalier-Smith & Chao 2003[225]
    • Class Granofilosea Cavalier-Smith & Bass in Bass et al. 2009[226]
    • Class Chlorarachnea (Chlorarachniophyceae) Hibberd & Norris 1984. Incertae sedis genus: Rhabdamoeba.[229]
    • Infraphylum Monadofilosa Cavalier-Smith 1997
      • Incertae sedis:
        • Order Discocelida Cavalier-Smith 1997, family Discoceliidae Cavalier-Smith 1993, orthog. emend. 2012, genus Discocelia.[227]
        • Order Krakenida Dumack et al. 2017 ex Cavalier-Smith 2018, family Krakenidae Dumack et al. 2017, genus Kraken.[230]
        • Family Katabiidae Cavalier-Smith in Cavalier-Smith & Oates 2012, genus Katabia.
        • Family Psammonobiotidae Golemansky 1974, emend. Meisterfeld 2002, genera Alepiella, Chardezia, Edaphonobiotus, Feuerbornia, Frenzelina, Lesquerella, Micramphora, Micropsammella, Nadinella, Ogdeniella, Psammonobiotus, Propsammonobiotus, Rhumbleriella.
        • Family Volutellidae Sudzuki 1979, genera Pseudovolutella, Volutella.
      • Order Cercomonadida Poche 1913, emend. Vickerman 1983, emend. Mylnikov 1986, emend. Karpov et al. 2006; emend Howe et al. 2009; emend Cavalier-Smith 2012
      • Order Paracercomonadida Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, family Paracercomonadidae Cavalier-Smith & Karpov 2012, genera Brevimastigomonas, Metabolomonas, Nucleocercomonas, Paracercomonas, Phytocercomonas.
      • Order Glissomonadida(P)[231] Howe & Cavalier-Smith in Howe et al. 2009 (Heteromitidae Kent 1880, emend. Mylnikov 1990, emend. Mylnikov & Karpov 2004). Genus not assigned to any family: Neuromorpha.[231]
      • Order Pansomonadida Vickerman in Vickerman et al. 2005
        • Family Agitatidae Cavalier-Smith & Bass in Bass et al. 2009, genus Agitata.
        • Family Aurigamonadidae Cavalier-Smith in Cavalier-Smith & Oates 2012, genus Aurigamonas.
      • Superfamily Sainouroidea Cavalier-Smith in Cavalier-Smith et al. 2009[234] (Helkesida Cavalier-Smith 2018)
      • Class Thecofilosea Cavalier-Smith 2003, emend. Cavalier-Smith 2011
        • Incertae sedis:
          • Order Matazida Cavalier-Smith in Cavalier-Smith & Chao 2012, family Matazidae Cavalier-Smith in Cavalier-Smith & Chao 2012, genus Mataza.[8][235]
        • Subclass Ventricleftia Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, order Ventricleftida Cavalier-Smith in Howe et al. 2011.
          • Family Ventrifissuridae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genus Ventrifissura.
          • Family Verrucomonadidae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genus Verrucomonas.
        • Subclass Tectosia Cavalier-Smith in Cavalier-Smith & Chao 2003, order Tectofilosida Cavalier-Smith 2003.[u]
          • Family Chlamydophryidae De Saedeleer, 1934, genera Chlamydophrys Cienkowski 1876, Diaphoropodon Archer 1869, Lecythium Hertwig & Lesser 1874, Katarium Solbach 2024,[237] Trachyrhizium Shiratori & Ishida 2016.
          • Family Fiscullidae Dumack, Mausbach and Bonkowski in Dumack et al. 2017, genera Fisculla, Omnivora.[238]
          • Family Pseudodifflugiidae De Saedeleer 1934, genera Pseudodifflugia, Lenkorania.[239]
          • Family Rhizaspididae Dumack, Mausbach & Bonkowski 2017, genus Rhizaspis.
        • Subclass Phaeodaria Haeckel 1879 (=Tripylea Hertwig 1879)
          • Phaeoconchia Haeckel 1879, genera Coelodendrum, Coelographis, Conchellium, Conchopsis.
          • Phaeocystina Haeckel 1879, genera Aulacantha, Aulographis, Cannoraphis.
          • Phaeogromia Haeckel 1879, genera Castanella, Challengeron, Haeckeliana, Medusetta, Tuscarora.
          • Phaeosphaeria Haeckel 1879, genera Aulosphaera, Cannosphaera, Sagosphaera.
        • Order Cryomonadida Cavalier-Smith 1993[240]
          • Family Rhogostomidae Dumack et al. 2017, genera Rhogostoma, Sacciforma, Capsellina.
          • Family Protaspidae Cavalier-Smith 1993 (="Cryomonadidae" Cavalier-Smith 1993), genera Cryothecomonas, Protaspa.
        • Order Ebriida[240][241] Deflandre 1936 (=Ebriacea Lemmermann 1901). Genus not assigned to any family: Botuliforma.[242]
          • Family Hermesinidae Hovasse 1943, genera Hermesinum, [8]Hermesinella plus about twelve extinct genera.
          • Family Ditripodiidae Deflandre 1951, four extinct genera.
          • Family Ammodochiidae Deflandre 1950, two extinct genera.
          • Family Ebriidae Lemmermann 1901, orthog. emend. Poche 1913. Ebria, Ebrinula.
      • Class Imbricatea(P) Cavalier-Smith 2011
        • Incertae sedis
          • Superorder Discomonada Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, order Discomonadida Cavalier-Smith in Scoble & Cavalier-Smith 2014, family Discomonadidae Cavalier-Smith in Scoble & Cavalier-Smith 2014, genus Discomonas.
        • Order Spongomonadida Hibberd 1983, family Spongomonadidae Karpov 1990, genera Spongomonas, Rhipidodendron.
        • Order Marimonadida Cavalier-Smith & Bass in Howe et al. 2011
          • Family Abolliferidae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genera Abollifer, Cowlomonas and probably Heterochromonas.
          • Family Auranticordidae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genera Auranticordis.[8][229]
          • Family Cyranomonadidae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genus Cyranomonas.
          • Family Pseudopirsoniidae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genus Pseudopirsonia.
        • Order Variglissida Cavalier-Smith in Scoble and Cavalier-Smith 2014
          • Family Clautriaviidae Cavalier-Smith in Cavalier-Smith & Scoble 2013, genus Clautriavia.
          • Family Nudifilidae Cavalier-Smith in Howe et al. 2011, genus Nudifila.
          • Family Quadriciliidae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genus Quadricilia.
        • Order Thaumatomonadida(P?)[243] Shirkina 1987
          • Family Thaumatomonadidae Hollande 1952. Allas, Hyaloselene, Reckertia, Thaumatomonas, Thaumatomastix, Ovaloplaca, Scutellomonas, Thaumatospina, Penardeugenia.
          • Family Peregriniidae Cavalier-Smith 2011. Gyromitus, Peregrinia.
          • Family Esquamulidae Shiratori et al. 2012, genus Esquamula.
        • Superorder Euglyphia Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018
          • Order Euglyphida Copeland 1956, emend. Cavalier-Smith 1997. Incertae sedis genera: Phaeobola,[244] Ampullataria, Euglyphidion, Heteroglypha, Matsakision, Pareuglypha and Pileolus.
            • Family Cyphoderiidae de Saedeleer 1934, genera Campascus, Corythionella, Cyphoderia [Schaudinnula], Messemvriella, Pseudocorythion, Ichthyosquama, Knarr, Oleiformis, Psammoderia.[245]
            • Family Paulinellidae de Saedeleer 1934, emend. Adl et al. 2012, genera Micropyxidiella, Ovulinata, Paulinella.
            • Suborder[246] Euglyphina Kosakyan et al. 2016. Genus not assigned to any family: Tracheleuglypha.[v]
              • Family Assulinidae Lara et al. 2007, genera Assulina, Placocista, Valkanovia.
              • Family Sphenoderiidae Chatelain et al. 2013, genera Sphenoderia, Trachelocorythion, Deharvengia.
              • Family Trinematidae Hoogenraad & De Groot 1940, emend Adl et al. 2012, genera Corythion, Playfairina, Puytoracia, Trinema.
              • Family Euglyphidae Wallich 1864, emend Lara et al. 2007, genera Euglypha, Scutiglypha.
          • Order Zoelucasida Cavalier-Smith in Scoble & Cavalier-Smith 2014, family Zoelucasidae Cavalier-Smith in Scoble & Cavalier-Smith 2014, genus Zoelucasa.
          • Order Trivalvulariida[247] Siemensma & Dumack 2020, family Trivalvulariidae Siemensma & Dumack 2020, genera Leptogromia, Trivalvularis.
      • Class Metromonadea Cavalier-Smith 2007, emend. Cavalier-Smith 2011
        • Order Metopiida Cavalier-Smith in Cavalier-Smith & Chao 2003
          • Family Metopiidae Cavalier-Smith in Cavalier-Smith & Chao 2003, genera Metopion, Micrometopion.
        • Order Metromonadida Bass & Cavalier-Smith 2004
          • Family Metromonadidae Bass & Cavalier-Smith 2004, genus Metromonas.
          • Family Kiitoksiidae Cavalier-Smith in Cavalier-Smith & Scoble 2014, genus Kiitoksia.
  • Subphylum Endomyxa(P)[248] Cavalier-Smith 2002. Genus not assigned to any lower taxon: Viscidocauda.[221]
    • Phytorhiza[249] Sierra et al. 2015
      • Class Vampyrellidea Cavalier-Smith 2018, order Vampyrellida West 1901, emend. Hess et al. 2012 (=Aconchulinida De Saedeleer 1934). Incertae sedis genera: Thalassomyxa, Arachnula, Gobiella, Lateromyxa, Penardia.[250]
        • Family Vampyrellidae Zopf 1885, genus Vampyrella.
        • Family Leptophryidae Hess, Sausen & Melkonian 2012, genera Arachnomyxa, Leptophrys, Planctomyxa, Platyreta, Pseudovampyrella,[251] Theratromyxa, Vernalophrys.
        • Family Placopodidae Jahn 1928 (=Hyalodiscidae Poche 1913), genus Placopus.
        • Family Sericomyxidae More, Simpson & Hess 2021, genus Sericomyxa.
      • Class Phytomyxea Engler & Prantl 1897. Genus not assigned to any lower taxon: Marinomyxa.[252]
    • Superclass Marimyxia Cavalier-Smith 2018
      • Order Reticulosida Cavalier-Smith in Cavalier-Smith & Chao 2003 emend. Bass et al. 2009, family Filoretidae Cavalier-Smith & Bass in Bass et al. 2009, genus Filoreta.
      • Order Gromiida Claparède & Lachmann 1856, family Gromiidae Reuss 1862, genus Gromia.
      • Class Ascetosporea Sprague 1979, emend. Cavalier-Smith 2009
        • Order Claustrosporida Cavalier-Smith in Cavalier-Smith & Chao 2003, genus Claustrosporidium.
        • Order Haplosporida Caullery & Mesnil 1899, genera Bonamia, Haplosporidium, Minchinia, Urosporidium.
        • Order Mikrocytida Hartikainen et al. 2013, family Mikrocytidae Cavalier-Smith in Cavalier-Smith, Chao & Lewis 2018, genera Mikrocytos, Paramikrocytos.
        • Order Paradiniida Cavalier-Smith in Bass et al. 2009, family Paradiniidae Schiller 1935, genus Paradinium.
        • Order Paramyxida Chatton 1911, genera Marteilia, Paramyxa, Paramarteilia, Marteilioides, Eomarteilia.
    • Family Heliomorphidae Cavalier-Smith & Bass in Bass et al. 2009, genus Heliomorpha.[248]

Foraminifera

Globothalamea

Xenophyophorea

'monothalamids'

'monothalamids'

Tubothalamea

'monothalamids'

Cladogram of foraminifera based on a 2022 phylogenetic analysis.[257]

The foraminifera, or forams, are a diverse group of single-celled aquatic amoebae, usually bearing an organic or calcareous wall, amounting to over 6,700 living species and many fossil taxa.[258] They were originally classified as an order of protozoa (Foraminiferida) belonging to the now obsolete Granoreticulosa, along with other reticulose amoebae. Later they were separated into their own phylum by most protozoologists, although maintained as a class by micropaleontologists,[259] until they were placed as a subphylum of phylum Retaria along with the Radiolaria.[3] They are divided into three classes (or subclasses, when globally treated as a class): the paraphyletic monothalamids,[260] containing amoebae with single-chambered organic walls and a few naked amoebae (e.g., the large xenophyophores); and the monophyletic Globothalamea and Tubothalamea, which evolved from monothalamids, each containing amoebae with multi-chambered tests, either organic or calcareous.[257] Some alternate systems of dividing foraminifera into classes have been proposed,[261] but none have gained consensus. The relationships of monothalamids remain a work in progress due to the limited amount of genetic data.[257]

Foraminiferal classification was compiled numerous times through the 20th century, culminating in 1987 with the catalogue of foraminiferal genera published by paleontologists Alfred R. Loeblich Jr and Helen Tappan.[262] Later, catalogues have been published individually for separate groups of foraminifera on the basis of morphology and ecology. Two classifications for exclusively agglutinated (organic-walled) foraminiferal genera were published in 2001[259] and 2014,[263] and one classification for planktonic foraminifera was published in 2022.[264]

Subphylum Foraminifera d'Orbigny 1826

  • ?Lagenida
  • ?Heterogromia
  • ?Komokiacea*
  • Class Monothalamea(P) Haeckel 1862 sensu Pawlowski et al. 2013 ('monothalamids').[260] Genera not assigned to any lower taxon: Adhaerentella,[265] Astrammina, Bathysiphon, Bowseria,[266] Crithionina, Flaviatella,[267] Notodendrodes, Psammophaga, Leannia,[268] Nujappikia.[269]
    • Family Lieberkuehniidae Siemensma et al. 2021, genera Lieberkuehnia, Claparedellus.[270]
    • Family Edaphoallogromiidae Siemensma et al. 2021, genus Edaphoallogromia.[270]
    • Family Lacogromiidae Siemensma & Holzmann 2021, genus Lacogromia.[270]
    • Family Limnogromiidae Holzmann & Siemensma 2021, genus Limnogromia.[270]
    • Family Schizamminidae Nørvang, 1961, genera Jullienella, Schizammina, Spiculosiphon.[271]
    • Family Velamentofexidae Völcker & Clauß 2021, genus Velamentofex.[270]
    • Order Allogromiida(P) Hartog in Harmer & Shipley 1906
      • Family Allogromiidae Rhumbler 1904, genera Allogromia, Vellaria.[272]
      • Family Reticulomyxidae Page 1987 emend. Hülsmann 2014, genera Reticulomyxa, Dracomyxa, Haplomyxa, Wobo.[273]
    • Order Astrorhizida Lankester 1885
      • Suborder Astrorhizina Lankester 1885
        • Superfamily Xenophyophoroidea Tendal 1972, genera Abyssalia, Aschemonella, Bizarria, Claraclippia, Galatheammina, Homogammina, Moanammina, Psammina, Reticulammina, Rhizammina, Semipsammina, Shinkaiya, Spiculammina, Stannophyllum, Stereodiktyoma, Syringammina, Tendalia.[274][275][276][277][278]
  • Class Globothalamea Pawlowski et al. 2012
    • Order Loftusiida Kaminski 2004
      • Suborder Biokovinina Kaminski 2004
        • Superfamily Biokovinoidea Gušić 1977
          • Family Charentiidae Loeblich & Tappan 1985, genera Charentia, Ismailia, Karaisella, Melathrokerion, Moncharmontia, Praekaraisella, Praepeneroplis.
        • Superfamily Coscinophragmatoidea Thalmann 1951
          • Family Haddoniidae Saidova 1981, genera Haddonia, Stylonina.
          • Family Coscinophragmatidae Thalmann 1951, genera Alpinophragmium, Ammotrochoides, Bdelloidina, Goellipora, Coscinophragma.
      • Suborder Loftusiina Kaminski & Mikhalevich 2004
        • Superfamily Haplophragmioidea Eimer & Fickert 1899
          • Family Cribratinidae Loeblich & Tappan 1964, genera Cribratina, Sievoides.
          • Family Haplophragmiidae Eimer & Fickert 1899, genus Haplophragmium.
          • Family Labyrinthidomatidae Loeblich & Tappan 1987, genera Bulbophragmium, Labyrinthidoma.
        • Superfamily Loftusioidea Brady 1884
          • Family Cyclamminidae Marie 1941
            • Subfamily Alveolophragmiinae Saidova 1981, genera Alveolophragmium, Popovia, Quasicyclammina, Reticulophragmoides, Reticulophragmium, Sabellovoluta.
            • Subfamily Buccicrenatinae Loeblich & Tappan 1985, genus Buccicrenata.
            • Subfamily Choffatellinae Maync 1958, genera Abuhammadina, Bramkampella, Choffatella, Paracyclammina, Torinosuella.
            • Subfamily Cyclammininae Marie 1941, genus Cyclammina.
            • Subfamily Hemicyclammininae Banner 1966, genera Alveocyclammina, Flabellamminopsis, Hemicyclammina.
            • Subfamily Pseudochoffatellinae Loeblich & Tappan 1985, genera Balkhania, Broeckinella, Dhrumella, Montsechiana, Pseudochoffatella, Torremiroella.
          • Family Ecougellidae Loeblich & Tappan 1985, genus Ecougella.
          • Family Everticyclamminidae Septfontaine 1988, genera Everticyclammina, Rectocyclammina.
          • Family Hottingeritidae Loeblich & Tappan 1985, genus Hottingerita.
          • Family Loftusiidae Brady 1884, genera Loftusia, Praereticulinella, Reticulinella.
          • Family Mesoendothyridae Voloshinova 1958
            • Subfamily Mesoendothyrinae Banner 1966, genera Audienusina, Mesoendothyra.
            • Subfamily Labyrinthininae Septfontaine 1988, genus Labyrinthina.
            • Subfamily Levantinellinae Fourcade, Mouty & Teherani 1997, genus Levantinella.
            • Subfamily Planiseptinae Septfontaine 1988 nom. nud., genera Planisepta, Paleomayncina, Orbitammina, Orbitopsella.
          • Family Ramalhoidae Schlagintweit 2024, genus Ramalhoa.[279]
          • Family Spirocyclinidae Munier-Chalmas 1887, genus Martiguesia, Pseudospirocyclina, Qataria, Reissella, Saudia, Sornayina, Spirocyclina, Sreptocyclammina, Thomasella, Vania.
          • Family Suraqalatiidae Schlagintweit & Rashidi 2018, genus Suraqalatia.[280]
          • Family Syrianidae Kaminski 2004, genus Syriana.
      • Suborder Orbitolinina Kaminski 2004
        • Superfamily Pfenderinoidea Smout & Sugden 1962
          • Family Bakhtiarellidae Schlagintweit & Rashidi 2022, genus Bakhtiarellia.[281]
          • Family Hauraniidae Septfontaine 1988
            • Subfamily Amijellinae Septfontaine 1988, genera Alveosepta, Alzonella, Alzonorbitopsella, Amijiella, Anchispirocyclina, Bostia, Ijdranella, Kastamonina, Palaeocyclammina, Pseudocyclammina, Redmondellina, Spiraloconulus.
            • Subfamily Hauraniinae Septfontaine 1988, genera Cymbriaella, Gutnicella, Haurania, Meyendorffina, Platyhaurania, Socotraina, Timidonella.
    • Order Rotaliida Delage & Hérouard 1896
      • Family Planorbulinidae Schwager 1877. Planorbulinella, Hyalinea.
      • Superfamily Discorboidea Ehrenberg 1838
        • Family Discorbidae Ehrenberg 1838. Discorbis.
        • Family Rosalinidae Reiss 1963. Rupertina, Discanomalina, "Rosalina", Gavelinopsis, Planorbulina.
      • Superfamily Rotalioidea Ehrenberg 1839, emend. Pawlowski 2013. Genera incertae sedis: Criboelphidium, "Elphidium", Protelphidium.
        • Family Elphidiidae Galloway 1933, genus Elphidium.
        • Family Ammoniidae Saidova 1981, genus Ammonia.
        • Family Elphidiellidae Holzmann & Pawlowski 2017, genus Elphidiella.
        • Family Haynesinidae Mikhalevich 2013, genera Haynesina, Aubignyna.
      • Superfamily Glabratelloidea Loeblich & Tappan 1964
        • Family Rotaliellidae Loeblich & Tappan 1964, genera Rotaliella, Rossyatella.
        • Family Buliminoididae Seiglie 1970, genus Buliminoides.
        • Family Glabratellidae Loeblich & Tappan 1964, genera Glabratella, Glabratellina, Angulodiscorbis, Planoglabratella.
      • Superfamily Calcarinoidea Schwager 1876
        • Family Calcarinidae Schwager 1876, genera Neorotalia, Baculogypsina, Baculogypsinoides, Schlumbergerella, Pararotalia.
      • Superfamily Nummulitoidea de Blainville 1827, family Nummulitidae de Blainville 1827, genera Nummulites, Operculinella, Cycloclypeus, Heterostegina, Operculina, Planoperculina, Planostegina.
      • Superfamily Serioidea Holzmann & Pawlowski 2017
        • Family Uvigerinidae Haeckel 1894, genera Uvigerina, Rectuvigerina, Trifarina.
        • Family Bolivinitidae Glaessner 1937, genera Bolivina, Brizalina, Saidovina.
        • Family Cassidulinidae d'Orbigny 1839, genera Globocassidulina, Cassidulinoides, Evolvocassidulina, Islandiella, Ehrenbergina
        • Family Sphaeroidinidae Cushman 1927, genus Sphaeroidina.
        • Family Globobuliminidae Cushman 1927, genus Globobulimina.
      • Incertae sedis families
        • ?Family Nonionidae Schultze 1854, genera Nonion, Nonionella, Nonionellina, Nonionoides.
        • ?Family Virgulinellidae Loeblich & Tappan 1984, genus Virgulinella.
        • ?Family Buliminidae Jones 1875, genus Bulimina.
        • ?Family Epistominellidae Holzmann & Pawlowski 2017, genus Epistominella.
        • ?Family Stainforthiidae Reiss 1963, genera Stainforthia, Gallitellia.
        • ?Family Cibicididae Cushman 1927, genera Cibicides, Cibicidoides, Heterolepa.
        • ?Family Chilostomellidae Brady 1881, genus Chilostomella.
        • ?Family Pullenidae Schwager 1877, genus Pullenia.
        • ?Family Nuttalidae Saidova 1981, genus Nuttalides.
        • ?Family Discorbinellidae Sigal 1952, genera Discorbinella, Hanzawaia.
        • ?Family Astrononionidae Cushman & Edwards 1937, genus Astrononion.
        • ?Family Oridorsalidae Loeblich & Tappan 1984, genus Oridorsalis.
        • ?Family Melonidae Holzmann & Pawlowski 2017, genus Melonis.
        • ?Family Cymbaloporidae Cushman 1927, genus Cymbaloporella.
        • ?Family Rubratelliidae Holzmann & Pawlowski 2017, genus Rubratella.
        • ?Family Murrayinelliidae Holzmann & Pawlowski 2017, genus Murrayinella.
    • Order Globigerinida(P) Lankester 1885 emend. Arz, Arenillas & Gilabert 2022[264]
      • Superfamily Parvularugoglobigerinoidea Arenillas, Arz & Gilabert 2022
        • Family Parvularuglobigerinidae Arenillas, Arz & Gilabert 2022, genera Pseudocaucasina, Palaeoglobigerina, Parvularugoglobigerina.
      • Superfamily Eoglobigerinoidea BouDagher-Fadel 2012
        • Family Eoglobigerinidae Blow 1979, genera Alicantina, Eoclavatorella, Eoglobigerina, Parasubbotina, Pseudoglobigerinella, Subbotina, Turbeogloborotalia.
        • Family Globoquadrinidae Blow 1979, genera Dentoglobigerina, Globoquadrina.
        • Family Neoacarininidae BouDagher-Fadel 2012, genus Neoacarinina.
        • Family Porticulasphaeridae Banner 1982, genera Globigerinatheka, Guembelitrioides, Inordinatosphaera, Orbulinoides, Porticulasphaera.
      • Superfamily Globigerinoidea Carpenter, Parker & Jones 1862
        • Family Globigerinidae Carpenter, Parker & Jones 1862, genera Alloglobigerinoides, Ciperoella, Globigerina, Globicuniculus, Globigerinoides, Globigerinoidesella, Globoturborotalita, Trilobigerina (=Trilobatus), Zeaglobigerina.
        • Family Globigerinellidae BouDagher-Fadel 2012, genera Beella, Bolliella, Globigerinella, Orcadia, Protentella, Quiltyella.
        • Family Hastigerinidae Bolli, Loeblich & Tappan 1957, genera Hastigerina, Hastigerinella, Hastigerinopsis.
        • Family Orbulinidae Schultze 1854, genera Biorbulina, Candorbulina, Orbulina, Praeorbulina.
        • Family Sphaeroidinellidae Banner & Blow 1959, genera Prosphaeroidinella, Sphaeroidinella, Sphaeroidinellopsis.
        • Family Turborotalitidae Hofker 1976, genera Berggrenia, Turborotalita.
      • Superfamily Globorotalioidea Cushman 1927
        • Family Catapsydracidae Bolli, Loeblich & Tappan 1957, genera Catapsydrax, Globigerinopsoides, Globigerinoita, Velapertina.
        • Family Globorotaloididae Banner & Blow 1959, genera Clavatorella, Globorotaloides, Protentelloides.
        • Family Globorotaliidae Cushman 1927, genera Dentigloborotalia, Globoconella, Globorotalia, Hirsutella, Jenkinsella, Menardella, Neogloboquadrina, Paragloborotalia, Truncorotalia.
        • Family Pulleniatinidae Cushman 1927, genus Pulleniatina.
      • Superfamily Globanomalinidoidea Loeblich & Tappan 1984, family Globanomalinidae Loeblich & Tappan 1984, genera Carinoturborotalia, Globanomalina, Luterbacheria, Planoglobanomalina, Turborotalia.
      • Superfamily Hantkeninoidea Cushman 1927
        • Family Pseudohastigerinidae Canudo 1990, genus Pseudohastigerina.
        • Family Hantkeninidae Cushman 1927, genera Applinella, Aragonella, Clavigerinella, Cribrohantkenina, Hantkenina.
      • Superfamily Truncorotaloidinoidea BouDagher-Fadel 2012
        • Family Globigerapsidae Blow 1979, genera Globigerapsis, Muricoglobigerina.
        • Family Planorotalitidae BouDagher-Fadel 2012, genera Astrorotalia, Planorotalites.
        • Family Truncorotaloididae Loeblich & Tappan 1961. Acarinina, Igorina, Morozovella, Morozovelloides, Pearsonites, Praemurica, Pseudogloboquadrina, Testacarinata, Truncorotaloides.
    • Order Globotruncanida Arz, Arenillas & Gilabert 2022[264]
      • Superfamily Abathomphaloidea Arz, Arenillas & Gilabert 2022
        • Family Abathomphalidae Pessagno 1967, genus Abathomphalus.
        • Family Globotruncanellidae Maslakova 1964, genera Globotruncanella, Spinoglobotruncanella.
      • Superfamily Favuselloidea Longoria 1974
        • Family Conoglobigerinidae BouDagher-Fadel, Banner & Whittaker 1997, genera Conoglobigerina, Tenuigerina, ?Sphaerogerina.
        • Family Favusellidae Longoria 1974, genera Ascoliella, Favusella, Koutsoukosia.
        • Family Globuligerinidae Loeblich & Tappan 1984, genera Compactogerina, Globuligerina, Haeuslerina, Petaloglobigerina.
      • Superfamily Hedbergelloidea Longoria & Gamper 1975
        • Family Ananiidae El-Nakhal 2010, genera Anania, Badriella, Costellagerina, Hillsella, Liuenella [Liuella], Loeblichella, Muricohedbergella, Paracostellagerina, Pessagnoina, Planohedbergella, Pseudoclavihedbergella, Vanhintella.
        • Family Hedbergellidae Loeblich & Tappan 1961, genera Asterohedbergella, Clavihedbergella, Hedbergella, Microhedbergella, Paraticinella, Pseudoguembelitria.
        • Family Helvetoglobotruncanidae Lamolda 1976, genera Angulocarinella, Bermudeziana, Bollitruncana, Fingeria, Hedbergellita, Brittonella, Helvetoglobotruncana, Unitruncatus, Whiteinella.
        • Family Praehedbergellidae Banner & Desai 1988, genera Blefuscuiana, Gorbachikella, Praehedbergella, Lilliputianella, Lilliputianelloides, Wondersella.
      • Superfamily Globotruncanoidea Brotzen 1942
        • Family Globotruncanidae Brotzen 1942, genera Contusotruncana, Globotruncana, Marginotruncana, Obliquacarinata, Sphaerotruncana, Ventrotruncana.
        • Family Praeglobotruncanidae Ion 1983, genera Concavatotruncana, Dicarinella, Falsotruncana, Rotundina, Praeglobotruncana, Verotruncana.
        • Family Reissidae Korchagin 2001, genera Elevatotruncana, Globotruncanita, Kassabiana, Radotruncana, Sigalitruncana, Turbotruncana.
      • Superfamily Planomalinoidea Bolli, Loeblich & Tappan 1957
        • Family Eohastigerinellidae Loeblich & Tappan 1984, genera Eohastigerinella, Hastigerinoides.
        • Family Globigerinelloididae Longoria 1974, genera Alanlordella, Allotheca, Biglobigerinella, Blowiella, Claviblowiella, Globigerinelloides, Pseudoschackoina.
        • Family Planomalinidae Bolli, Loeblich & Tappan 1957, genera Bannerina, Planomalina, Pseudoplanomalina.
        • Family Schackoinidae Pokorný 1958, genera Asymetria, Groshenyia, Leupoldina, Neoschackoina, Schackoina.
      • Superfamily Rotaliporoidea Sigal 1958
        • Family Rotaliporidae Sigal 1958, genera Anaticinella, Pseudothalmanninella, Rotalipora, Thalmanninella.
        • Family Ticinellidae Longoria 1974, genera Biticinella, Claviticinella, Ticinella.
      • Superfamily Rugoglobigerinoidea Subbotina 1959
        • Family Helvetiellidae Longoria & Gamper 1984, genera Archaeoglobigerina, Bucherina, Dorbignya, Edgarinella, Gandolfia, Gansserina, Globocarinata, Helvetiella, Kuglerina.
        • Family Rugoglobigerinidae Subbotina 1959, genera Archaeoglobitruncana, Plummerita, Rugoglobigerina, Rugosocarinata, Rugotruncana, Trinitella.
    • Order Heterohelicida Fursenko 1958 emend. Arz, Arenillas & Gilabert 2022[264]
      • Superfamily Heterohelicoidea Cushman 1927
        • Family Gublerinidae Aliyulla 1977, genera Gublerina, Lipsonia, Praegublerina.
        • Family Heterohelicidae Cushman 1927, genera Braunella, Bronnimannella, Ehrenbergites, Globoheterohelix, Fleisherites, Hartella, Heterohelix, Huberella, Laeviheterohelix, Lazarusina, Lunatriella, Magellanina, Mihaia, Nederbragtina, Planoheterohelix, Protoheterohelix, Pseudoplanoglobulina, Steineckia, Striataella, Texasina, ?Bifarina, ?Rectoguembelina, ?Zeauvigerina.
        • Family Pseudotextulariidae Maamouri & Salaj 1978, genera Planoglobulina, Pseudotextularia, Racemiguembelina.
        • Family Pseudoguembelinidae Aliyulla 1977, genera Eicheriella, Leptobimodalia, Pseudoguembelina.
        • Family Spiroplectidae Cushman 1911, genera Hendersonites (=Hendersonia), Neohendersonites, Paraspiroplecta, Spiroplecta.
        • Family Ventilabrellidae Maamouri & Salaj 1978, genera Planulitella, Proliferania, Sigalia, Ventilabrella.
    • Order Guembelitriida Arenillas, Arz & Gilabert 2022[264]
      • Superfamiily Cassigerinelloidea Bolli, Loeblich & Tappan 1957, family Cassigerinellidae Bolli, Loeblich & Tappan 1957, genera Cassigerinella, Riveroinella.
      • Superfamily Guembelitrioidea Montanaro-Gallitelli 1957, family Guembelitriidae Montanaro-Gallitelli 1957, genera Cassigerinelloita, Guembelitria, Chiloguembelitria, Jenkinsina, ?Archaeoguembelitria, ?Gallitellia, ?Guembelitriella.
      • Superfamily Chiloguembelinoidea Reiss 1963, family Chiloguembelinidae Reiss 1963, genera Chiloguembelina, Woodringina, ?Streptochilus.
      • Superfamily Globoconusoidea BouDagher-Fadel 2012, family Globoconusidae BouDagher-Fadel 2012, genera Globoconusa, Trochoguembelitria,
    • Order ? (unnamed)[264]
      • Superfamily Globigerinitoidea BouDagher-Fadel 2012, emend. Arenillas, Arz & Gilabert 2022[264]
        • Family Candeinidae Cushman 1927. Candeina.
        • Family Globigerinatellidae BouDagher-Fadel 2012. Globigerinatella.
        • Family Globigerinitidae Bermúdez 1961, genera Globigerinita, Mutabella, Polyperibola, Tinophodella.
        • Family Tenuitellidae BouDagher-Fadel 2012, genera Praetenuitella, Tenuitella, Tenuitellinata, Tenuitellita.
        • Family ? (unnamed), genera Dipsidripella, ?Antarcticella.
    • Order Robertinida Loeblich & Tappan 1984, genera Hoeglundina, Robertina, Robertinoides.
    • Order Textulariida(P) Delage & Hérouard 1896, genera Cyclammina, Eggerella, Reophax, Textularia, Trochammina.
    • Order Carterinida Loeblich & Tappan 1981, genus Carterina.

Radiolaria

  • Radiolaria Müller 1858, sensu Adl et al. 2005
    • Acantharea Haeckel 1881, emend. Mikrjukov 2000
      • Chaunocanthida Schewiakoff 1926. Amphiacon, Conacon, Gigartacon, Heteracon, Stauracon.
      • Holocanthida Schewiakoff 1926. Acanthochiasma, Acanthocolla, Acanthoplegma.
      • Symphyacanthida Schewiakoff 1926. Amphilithium, Astrolonche, Pseudolithium.
      • Arthracanthida Schewiakoff 1926. Acanthometra, Daurataspis, Dictyacantha, Diploconus, Phractopelta, Phyllostaurus, Pleuraspis, Stauracantha.
    • Taxopodida Fol 1883. Sticholonche.
    • Polycystinea Ehrenberg 1839 stat. nov. Levine et al. 1980[282]
      • Spumellaria Ehrenberg 1876 stat. nov. Haeckel 1884
        • Hexacromyoidea Haeckel 1882 stat. nov. Suzuki et al. 2021 [Hexalonchata Afanasieva et al. 2005]
          • Hexacaryidae Haeckel 1882 stat. nov. Suzuki et al. 2021: Clevepilegma Dumatrica 2013, Haliphormis Ehrenberg 1846 [Hexastylanthus, Hexastylettus; Hexastylissus; Hexastylurus], Hexacaryum Haeckel 1882, Hexalonchetta Haeckel 1887, Hexancistra Haeckel 1879 [Hexancora], Hexapitys Haeckel 1882.
          • Hexacromyidae Haeckel 1882 stat. nov. Suzuki et al. 2021: Carpocanthum Chen & Tan 1989, Hexacromyum Haeckel 1882 [Cubosphaera; Hexacontura], Hexalonchilla Haeckel 1887 [Hexalonchusa; Staurolonchantha], Nanina Kozur & Mostler 1982 [Pentactinosphaera].
          • Hollandosphaeridae Deflandre 1973: Anomalosoma Loeblich & Tappan 1961 [Heterosoma Hollande & Enjumet 1960, Hollandosphaera Deflandre 1973 [Heliaster Hollande & Enjumet 1960], Tetrapetalon Hollande & Enjumet 1960.
        • Spongosphaeroidea Haeckel 1862Spongosphaeridae Haeckel 1862: Diplospongus Mast 1910, Spongodendron Hollande & Enjumet 1960, Spongosphaera Ehrenberg 1847 [Hexadoridium; Spongosphaeromma].
        • Lithocyclioidea Ehrenberg 1846
          • Astracturidae Haeckel 1882: Astromma Ehrenberg 1846 [Astractinium; Astractura; Astracturium; Astrococcura; Staurococcura], Amphactura Haeckel 1882 [Dicoccura; Diplactinium], Hymeniastrum Ehrenberg 1846 [Hymenastrella; Hymenactura; Hymenacturium; Trigonactinium; Hymenactinium; Pentactura; Trigonacturium].
          • Lithocycliidae Ehrenberg 1846: Cromyatractus Haeckel 1887 [Cromyatractium; Caryatractus], Heliosestrum Haeckel 1882 [Heliosestantha; Astrosestrum; Astrosestantha; Astrophacura; Staurodiscus Krasheninnikov 1960]; Heliostylus Haeckel 1882 [Astrostylus; Stylodiscus; Stylentodiscus], Lithocyclia Ehrenberg 1846 [Astrocyclia; Coccodiscus], Phacostaurus Haeckel 1882 [Phacostaurium, Astrostaurus, Crucidiscus, Heliostaurus, Sethostaurium, Sethostaurus, Staurentodiscus], Phacotriactis Sutton 1896, Sethostylus Haeckel 1882 [Sethostylium; Amphicyclia; Phacostylus; Phacostylium], Staurocyclia Haeckel 1882 [Coccostaurus], Triactiscus Haeckel 1882 [Trigonocyclia].
          • Panartidae Haeckel 1887: Cannartus Haeckel 1882 [Cannartidissa; Cannartiscus; Pipetta; Pipettaria; Pipettella; Druppula; Druppuletta], Diartus Sanfilippo & Riedel 1980, Didymocyrtis Haeckel 1862 [Artidium; Cyphinura; Cyphocolpus; Desmartus; Ommatocampula; Panaromium; Panartus; Panartella; Panartidium; Panartissa; Panartura; Peripanartium; Peripanartula; Peripanartus; Peripanicula], Spongolivella Dumitrica 2021.
          • Phacodiscidae Haeckel 1882: Periphaena Ehrenberg 1874 [Astrophacomma; Heliodiscomma; Perizona], Phacodiscus Haeckel 1882 [Phacodiscinus; Astrophacilla; Paracenodiscus; Phacodisculus; Prunulum; Prunuletta; Sethodiscinus].
        • Spongodiscoidea Haeckel 1862 emend. Suzuki 2021
          • Spongodiscidae Haeckel 1862: Spongaster Ehrenberg 1861 [Spongastrella; Histiastrella], Spongodiscus Ehrenberg 1854 [Spongodisculus], Spongotrochus Haeckel 1861 [Spongotrochiscus].
          • Euchitoniidae Stöhr 1880 emend. Suzuki 2021: Amphicraspedum Haeckel 1882 [Amphicraspedon; Aphirrhopella], Dictyocoryne Ehrenberg 1861 [Dictyocorynula; Dictyastrum; Dictyastrella; Euchitonia; Hymenastromma; Rhopalodictya; Rhopalodictyum; Styla; Pteractis], Hexinastrum Haeckel 1882 [Hexalastromma; Pentalastromma; Pentinastrum], Ommatocampe Haeckel 1861 [Ommatocampium; Amphymenium], Tessarastrum Haeckel 1887 [Tessarastrella; Hagiastromma; Tessarostromma], Tricanastrum Haeckel 1879 [Dicranaster; Dicranastrum; Myelastrella; Myelastrum; Spongomyelastrum; Myelastromma; Pentophiastromma; Spongodicranastrum; Spongohagiastrum; Spongopentophiastrum; Spongostaurina; Tetracranastrum; Triastrum], Trigonastrum Haeckel 1887 [Trigonastrella; Rhopalastromma; Chitonastromma; Amphicraspedina; Amphirrhopoma; Dictyastromma; Monaxonium; Trigonastromma].
          • Spongobrachiidae Haeckel 1882 emend. Suzuki 2021: Spongasteriscus Haeckel 1862 [Spongasterisculus; Dictyocorynium], Spongastromma Haeckel 1887, Spongobrachium Haeckel 1882.
        • Cladococcoidea Haeckel 1862 stat. nov. Suzuki et al. 2021
          • Ethmosphaeridae Haeckel 1862: Cyrtidosphaera Haeckel 1861, Ethmosphaera Haeckel 1861, [Ethmosphaerella; Monosphaera], Haplosphaera Hollande & Enjumet 1960, Heliosphaera Haeckel 1861 [Heliosphaerella], Liosphaera Haeckel 1887 [Melitomma, Craspedomma].
          • Cladococcidae Haeckel 1862: Arachnosphaera Haeckel 1861 [Arachnosphaerella], Arachnospongus Mast 1910, Cladococcus Müller 1856 [Cladococcalis; Anomalacantha; Cladococcodes; Cladococcurus; Porococcus], Diplosphaera Haeckel 1861 [Diplosphaeromma; Astrosphaera; Diplosphaerella; Leptosphaera; Leptosphaerella; Astrosphaerella; Astrospongus; Drymosphaeromma; Leptosphaeromma], Haeckeliella Hollande & Enjumet 1960, Lychnosphaera Haeckel 1882 [Rhizoplegmidium, Rhizospongus, Thalassoplegma].
        • Trematodiscoidea Haeckel 1862 emend. Suzuki 2021Trematodiscidae Haeckel 1862 emend. Suzuki 2021: Flustrella Ehrenberg 1839 [Centrospira; Discospirella; Trematodiscus; Perichlamydium; Perispirella; Stylochlamyum], Staurospira Haeckel 1887 [Staurodictyon; Tholodiscus; Xiphospira], Stylodictya Ehrenberg 1846 [Stylodictyon; Stylochlamydium; Stylochlamys; Stylospongia; Stylocyclia; Stylospira], Tripodictya Haeckel 1882 [Xiphodictyon].
        • Haliommoidea Ehrenberg 1846
          • Actinommidae Haeckel 1862 emend. Suzuki 2021: Actinomma Haeckel 1861 [Actinommetta; Haliommura; Rhaphidococcus; Riedelipyle; Dreyerella; Drymyomma; Cromyomma; Echinommura; Heliosomura; Spheropyle], Cromyechinus Haeckel 1882 [Cromyodrymus], Rhaphidocapsa Haeckel 1887, Sphaeractis Brandt in Wetzel 1936, Staurocaryum Haeckel 1882, Stomatosphaera Dreyer 1889, Stuermeria Deflandre 1964.
          • Haliommidae Ehrenberg 1846 emend. Suzuki 2021: Cromyosphaera Haeckel 1882 [Cromyommetta; Cromyommura], Haliomma Ehrenberg 1839 [Actinommilla; Cenosphaera; Circosphaera; Thecosphaerella], Haliommantha Haeckel 1887, Hexacontella Haeckel 1887, Melittosphaera Haeckel 1882 [Conoactinomma], Pseudostaurosphaera Krasheninnikov 1960 [Pseudostaurolonche].
          • Heliodiscidae Haeckel 1882 sensu De Wever et al. 2001: Actinommura Haeckel 1887 [Excentrosphaerella], Excentrococcus Dumitrica 1978, Excentrodiscus Hollande & Enjumet 1960, Heliodiscus Haeckel 1862 [Heliodiscilla, Heliocladus, Heliodiscetta, Heliodrymus, Heliodendrum, Heliosestilla], Helioferrusa Dumitrica 2019, Phaenicosphaera Haeckel 1887 [Dreyeropyle].
        • Lithelioidea Haeckel 1862 sensu Matsuzaki et al. 2015
          • Conocaryommidae Lipman 1969: Conocaryomma Lipman 1969 [Conocromyomma].
          • Litheliidae Haeckel 1862 emend. Suzuki 2021: Lithelius Haeckel 1861 [Lithospira; Azerbaidjanicus], Middourium Kozlova 1999 [Monobrachium], Spiremaria Kozlova 1960 [Spiromultitunica], Spongocyclia Haeckel 1862 [Lithocarpium; Ommatodiscinus; Ommatodiscus; Ommatodisculus].
          • Phaseliformidae Pessagno 1972: Phaseliforma Pessagno 1972.
          • Pyramispongiidae Kozur & Mostler 1978 sensu O'Dogherty 1994: Pyramispongia Pessagno 1973 [Nodotetraedra].
          • Sponguridae Haeckel 1862: Ommatogramma Ehrenberg 1861 [Spongurus; Spongocorisca; Spongurantha; Spongurella].
        • Spongopyloidea Dreyer 1889 emend. Suzuki 2021
          • Spongopylidae Dreyer 1889 emend. Suzuki 2021: Schizodiscus Dogiel in Dogiel & Reshetnyak 1952, Spongobrachiopyle Kozur & Mostler 1978, Spongopyle Dreyer 1889 [Spongopylarium], Spongospira Stöhr 1880.
          • Cristallosphaeridae Popofsky 1912: Calcaromma Thomson 1877 [Cristallosphaera], Enalomelon Sugiyama 1992.
          • Prunopylidae Poche 1913: Prunopyle Dreyer 1889, Spongopylidium Dreyer 1889.
        • Phorticioidea Haeckel 1882 stat. nov. Suzuki et al. 2021 [Larnacillilae De Wever et al. 2001]
          • Amphitholidae Haeckel 1887 stat. nov. sensu De Wever et al. 2001
          • Circodiscidae Dumitrica 1989 stat. nov. Suzuki et al. 2021
          • Cryptolarnaciidae Dumitrica 1989 stat. nov. Suzuki et al. 2021
          • Histiastridae Dumitrica 1989 stat. nov. Suzuki et al. 2021
          • Phorticiidae Haeckel 1882 sensu Dumitrica 1989
        • Larcospiroidea Haeckel 1887 stat. nov. sensu Dumitrica 1989
          • Dipylissidae Dumitrica 1989 stat. nov. Suzuki et al. 2021
          • Larcospiridae Haeckel 1887 stat. nov. Suzuki et al. 2021
          • Palaeotetrapylidae Dumitrica 1989 stat. nov. Suzuki et al. 2021
          • Pylodiscidae Haeckel 1887 sensu Dumitrica 1989
          • Zonariidae Haeckel 1887 sensu Dumitrica 1989
        • Pseudoaulophacoidea Riedel 1967 sensu De Wever et al. 2001
          • Patulibracchiidae Pessagno 1971 sensu De Wever et al. 2001
          • Pseudoaulophacidae Riedel 1967 sensu De Wever et al. 2001
          • Suttoniidae Schaaf 1976 sensu Dumitrica 2019
        • Stylosphaeroidea Haeckel 1887 sensu Dumitrica 1984
          • Entapiidae Dumitrica in De Wever, Dumitrica, Caulet Nigrini & Caridroit 2001
          • Stylatractidae Schröder 1909 emend. Suzuki 2021
          • Tubosphaeridae Suzuki 2021
      • Nassellaria Ehrenberg 1875 emend. Haeckel 1887. Artostrobus, Eucyrtidium, Lithomelissa, Pterocanium, Pterocorys.
      • Collodaria Haeckel 1887. Acrosphaera, Collosphaera, Collozoum, Sphaerozoum, Rhaphidozoum, Siphonsphaera, Thalassicolla.
      • Orodaria Nakamura & Suzuki 2020[283]
        • Oroscenidae Haeckel 1887 emend. Nakamura & Suzuki 2021 [Orosphaerida Haeckel 1887; Orosphaeridae Haecker 1908]. Oroscena, Orostaurus, Oropelex. Nomina dubia genera: Orosphaera, Orodictyum, Orona, Oronium.
        • Thalassothamnidae Haecker 1906 emend. Nakamura & Suzuki 2021 [Cytocladidae Schröder, 1908]. Thalassothamnus, Cytocladus. Nomen dubium genus: Conostylus.
      • Entactinaria Kozur & Mostler 1982 sensu Nakamura & Suzuki 2020[w]
        • Entactiniidae Riedel 1967. Afanasievella, Apophysiactinia, Borisella, Callela, Cancellosphaera, Costaentactinia, Cyclocarpus nomen dubium, Duodecimentactinia, Langsonsphaera,[284] Entactinosphaera, Gracilentactinia, Holdisphaera, Involutentactinia, Kashiwara, Magnentactinia, Magnisphaera, Microporosa, Moskovistella, Multientactinia, Munzuwonella, Paratriposphaera, Perforentactinia, Plenoentactinia, Plenosphaera, Pluristratoentactinia, Polyedroentactinia, Provisocyntra, Radiobisphaera, Retentactinia, Retisphaera, Sinosphaera, Spongentactinia, Stigmosphaerostylus, Trilonche, Uberinterna, Wuyia.[285]
        • Tetrentactiniidae Kozur & Mostler 1979. Multisphaera.
        • Triassothamnidae Takahashi, Maekawa & Dumitrica 2022. Triassothamnus.[284]

Disparia

Cladogram of Disparia based on a 2025 phylogenomic analysis.[286]

Disparia is a clade that unites several predatory protists, namely the provorans, hemimastigotes, and two mysterious genera Meteora and Solarion. It was described in 2025 through phylogenomic analyses that accompanied the discovery of Solarion.[286] Prior to these analyses, provorans, hemimastigotes and Meteora were considered 'orphan' taxa, with unstable phylogenetic positions. The first provoran, Ancoracysta twista, was briefly proposed to be related to Haptista.[8] However, in 2024 there was already evidence of a close affinity between Meteora, hemimastigotes, and provorans.[287] The phylum Caelestes, described in 2025, encompasses two monotypic genera of protists with a unique stalked extrusome used for immobilizing prey bacteria. Their morphology resembles that of celestial bodies, after which they are named. Only one of the genera, Solarion, is assigned to a family, and no classes or orders have been defined.[286] Hemimastigotes are a small group composed of ten species of heterotrophs with a pellicle and numerous flagella. First identified in 1988,[288] they remained an orphan group for decades due to the absence of genetic information, with taxonomists hypothesizing affinities to many different protists.[289] In 2018, two hemimastigotes were successfully sequenced and a phylogenomic analysis revealed their deep-branching placement near Diaphoretickes.[290] Between 2024 and 2025, a closer relationship with the clades Provora and Caelestes was resolved.[287][286] Provorans compose two ancient phyla of predatory microbes and a total of eight described species. They are small, fast-swimming predators capable of consuming larger prey, but are easily confused with other protists due to their unremarkable appearance; they required meticulous study to be recognized.[291][292][293]

Excavates

Malawimonadida

Metamonada

The metamonads were first described by Pierre-Paul Grassé in the first volume of Traité de Zoologie, published in 1952, as the superorder Metamonadina or Anaxostylaria. They were originally composed of zooflagellates with four or more flagella, known as polymastigotes and hypermastigotes (e.g., Trichomonas, Oxymonas).[296] These were later split into other groups such as the Parabasalia and Preaxostyla (over 260 and 140 species respectively),[219] regarded as individual phyla. After rRNA phylogenetic analyses demonstrated their relatedness, the concept of metamonads was reintroduced by Cavalier-Smith as a monophyletic phylum Metamonada that includes both groups, as well as the anaerobic Fornicata (e.g., the free-living Carpediemonas and the parasitic Giardia;[297][298] around 140 species).[219] In this system, Preaxostyla is known as subphylum Anaeromonada, and Fornicata and Parabasalia are two infraphyla that belong to the subphylum Trichozoa.[4] Still, some taxonomists retain the Parabasalia at a phylum level.[299]

The classifications of Preaxostyla and Fornicata were last revised separately in the 2017 Handbook of the protists[300][301][302] and the higher classification of Metamonada was revised by Cavalier-Smith in 2021.[4] The classification of Parabasalia was completely updated in 2024.[299] Two new smaller clades of metamonads have been described in addition: anaeramoebae[303] and the 'BaSk' clade, containing barthelonids and skoliomonads.[304] However, Parabasalia was treated as a separate phylum by the 2024 revision, instead of a member of phylum Metamonada.[299]

Phylum Metamonada Grassé 1952 emend. stat. n. Cavalier-Smith 2003

  • Family Anaeramoebidae Táborský, Pánek & Čepička 2017, genus Anaeramoeba.
  • Subphylum Anaeromonada (=Preaxostyla Simpson 2003), class Anaeromonadea Cavalier-Smith 1996 emend. 2003
  • Subphylum Trichozoa(P)[305] Cavalier-Smith 1997
    • Infraphylum Fornicata Simpson 2003 stat. n. Cavalier-Smith 2022. Genus not assigned to any lower taxon: Aduncisulcus.
    • Infraphylum Parabasalia Honigberg 1973. Genera incertae sedis: Chilomitus, Rhizonympha, Tricercomitus, Trichocovina.
      • Class Hypotrichomonadea Čepička, Hampl & Kulda 2010, order Hypotrichomonadida Čepička, Hampl & Kulda 2010, family Hypotrichomonadidae Honigberg 1963 emend. Čepička, Hampl & Kulda 2010, genera Hypotrichomonas, Trichomitus.
      • Class Pimpavickea Boscaro & Keeling 2024, order Pimpavickida Céza & Čepička 2022, family Pimpavickidae Céza & Čepička 2022, genera Pimpavicka, Alexandriella.
      • Class Trichomonadea Kirby 1947 sensu Čepička, Hampl & Kulda 2010
        • Order Honigbergiellida Čepička, Hampl & Kulda 2010 emend. Boscaro & Keeling 2024
          • Family Hexamastigidae Čepička, Hampl & Kulda 2010 emend. Boscaro & Keeling 2024, genus Hexamastix.
          • Family Honigbergiellidae Čepička, Hampl & Kulda 2010, genera Honigbergiella, Ditrichomonoides, Honigbergiellopsis, Monotrichomonas.
          • Family Cthulhuidae Boscaro & Keeling 2024, genera Cthulhu, Cthylla, Nyarlathotep.
          • Family Tetratrichomastigidae Boscaro & Keeling 2024, genus Tetratrichomastix.
        • Order Trichomonadida Kirby 1947 sensu Čepička, Hampl & Kuda 2010. Genera incertae sedis: Pseudotrichomonas, Paleotrichomones.[314]
          • Family Lacusteriidae Céza & Čepička 2022, genus Lacusteria.
          • Family Trichomonadidae Chalmers & Pekkola 1918 sensu Hampl, Vrlík, Čepička, Pecka, Kulda & Tachezy 2006, genera Trichomonas, Cochlosoma, Cyathosoma, Pentatrichomonas, Pentatrichomonoides, Pseudotrypanosoma, Ptychostoma, Tetratrichomonas, Trichomitopsis, Trichomonoides.
      • Clade "Tla"
        • Class Lophomonadea Boscaro & Keeling 2024, order Lophomonadida Light 1927 emend. Cavalier-Smith 2013, family Lophomonadidae Kent 1880 emend. Cavalier-Smith 2013, genera Lophomonas, Eulophomonas, Prolophomonas.
        • Class Trichonymphea Poche 1913, order Trichonymphida Poche 1913
          • Family Burmanymphidae Poinar 2009, genus Burmanympha.[314]
          • Family Barbulanymphidae Boscaro & Keeling 2024, genera Barbulanympha, Rhynchonympha, Urinympha.
          • Family Hoplonymphidae Light 1926 emend. Boscaro & Keeling 2024, genus Hoplonympha.
          • Family Retractinymphidae Radek & Brune 2023, genus Retractinympha.
          • Family Spirotrichosomidae Hollande & Carruette-Valentin 1971, genera Spirotrichosoma, Apospironympha, Bispironympha, Colospironympha, Heliconympha, Leptospironympha, Macrospironympha.
          • Family Staurojoeninidae Grassi 1917, genera Staurojoenina, Idionympha.
          • Family Teranymphidae Koidzumi 1921, genera Tetranympha, Eucomonympha, Pseudotrichonympha.
          • Family Trichonymphidae Kent 1880, genus Trichonympha.
      • Clade "Cadamassta"
        • Class Cristamonadea Čepička, Hampl & Kulda 2010. Genera incertae sedis: Cyclojoenia, Joenia, Joenina, Joenoides, Joenopsis, Pachyjoenia, Parajoenopsis, Placojoenia, Projoenia.
          • Order Calonymphida Boscaro & Keeling 2024
            • Family Calonymphidae Grassi 1911 sensu Gile 2011, genera Calonympha, Criconympha, Daimonympha, Diplonympha, Gyronympha, Metastephanonympha, Prosnyderella, Snyderella, Stephanonympha.
            • Family Deltotrichonymphidae Brugerolle & Lee 2000, genera Deltotrichonympha, Koruga.
            • Family Mixotrichidae Boscaro & Keeling 2024, genus Mixotricha.
          • Order Devescovinida Boscaro & Keeling 2024, family Devescovinidae Doflein 1911 emend. Boscaro & Keeling 2024, genera Devescovina, Achemon, Astronympha, Bullanympha, Caduceia, Coronympha, Evemonia, Foaina, Hyperdevescovina, Kirbynia, Kofoidia, Macrotrichomonas, Macrotrichomonoides, Metadevescovina, Parajoenia, Polymastigoides, Pseudodevescovina, Runanympha, Devescovites.[314]
          • Order Gigantomonadida Boscaro & Keeling 2024, family Gigantomonadidae Boscaro & Keeling 2024, genus Gigantomonas.
        • Class Dientamoebea Boscaro & Keeling 2024, order Dientamoebida Boscaro & Keeling 2024, family Dientamoebidae Grassé 1953, genera Dientamoeba, Histomonas, Parahistomonas, Protrichomonas.
        • Class Monocercomonadea Boscaro & Keeling 2024, order Monocercomonadida Boscaro & Keeling 2024, family Monocercomonadidae Kirby 1944, genus Monocercomonas.
        • Class Simplicimonadea Boscaro & Keeling 2024, order Simplicimonadida Boscaro & Keeling 2024, family Simplicimonadidae Čepička, Hampl & Kulda 2010, genus Simplicimonas.
        • Class Tritrichomonadea Čepička, Hampl & Kulda 2010 emend. Boscaro & Keeling 2024, order Tritrichomonadida Čepička, Hampl & Kulda 2010 emend. Boscaro & Keeling 2024, family Tritrichomonadidae Čepička, Hampl & Kulda 2010, genus Tritrichomonas.
        • Class Spirotrichonymphea Grassé 1952 sensu Čepička, Hampl & Kulda 2010
          • Order Cononymphida Boscaro & Keeling 2024, family Cononymphidae Boscaro & Keeling 2024, genus Cononympha.
          • Order Holomastigotoidida Boscaro & Keeling 2024, family Holomastigotoididae Grassi & Foà 1911, genera Holomastigotoides, Rostronympha.
          • Order Spirotrichonymphida Grassé 1952
            • Family Brugerollinidae Boscaro & Keeling 2024, genera Brugerollina, Pseudospironympha.
            • Family Fraterculidae Boscaro & Keeling 2024, genera Fraterculus, Cuppa.
            • Family Holomastigotidae Janicki 1915, genera Holomastigotes, Spiromastigotes, Spirotrichonymphella, Uteronympha.
            • Family Spirotrichonymphidae Grassi 1917, genera Spirotrichonympha, Microjoenia, Micromastigotes, Nanospironympha, Spironympha, Torquenympha.
  • Incertae sedis
    • Class Notopharyngea Shiratori et al. 2026 (=BaSk Williams et al. 2024[315])[316]
      • Order Barthelonida Shiratori et al. 2026, family Barthelonidae Shiratori et al. 2026, genera Barthelona, Microbarthelona, Parabarthelona.
      • Order Skoliomonadida Shiratori, Eglit, Yazaki, Inagaki & Simpson 2026, family Skoliomonadidae Shiratori, Eglit, Yazaki, Inagaki & Simpson 2026, genus Skoliomonas.

Discoba

Jakobida

Tsukubamonadida

Heterolobosea

Pharyngomonadida

Tetramitia

Multisulcus

Selenaionea

Neovahlkampfiida

Selenaionida

Eutetramitea

Naegleriida

Percolomonadida

Pseudociliatida

Creneida

Lyromonadida

Cladogram of heterolobosean orders based on combined phylogenomic and 18S rRNA analyses published in 2025.[320][321]

The phylum Heterolobosea contains around 170 species of amoebae, flagellates, and amoeboflagellates. It was initially established to unite two historically well-known amoeboid orders, Schizopyrenida (such as Naegleria fowleri, a human pathogen) and Acrasida (slime molds). Later, as more flagellates joined this grouping, the usage of Heterolobosea was split between two meanings: the more common usage applies to the entire clade,[6] while the usage by Cavalier-Smith and collaborators was restricted to a paraphyletic class of "traditional" heteroloboseans, with the name Percolozoa used for the phylum instead.[322][323] The first comprehensive phylogenomic study of Heterolobosea was published in 2025 by Tomáš Pánek and coauthors, resulting in its modern classification.[320]

Phylum Heterolobosea Page & Blanton 1985 sensu Hanousková et al. 2019 (=Percolozoa Cavalier-Smith 1991)

  • Subphylum Pharyngomonada Cavalier-Smith 2008
    • Class Pharyngomonadea Cavalier-Smith in Cavalier-Smith & Nikolaev 2008
      • Order Pharyngomonadida Cavalier-Smith in Cavalier-Smith & Nikolaev 2008
        • Family Pharyngomonadidae Cavalier-Smith in Cavalier-Smith & Nikolaev 2008, genus Pharyngomonas.
  • Subphylum Tetramitia Cavalier-Smith 1993
    • Multisulcus malaysiensis Prokina et al. 2025, nom. prov.[321]
    • Class Selenaionea Pánek & Čepička 2025
      • Order Neovahlkampfiida Cavalier-Smith 2022 emend. Pánek et al. 2025
        • Family Neovahlkampfiidae Hanousková et al. 2018, genus Neovahlkampfia.
        • Family Orodruinidae Shɨshkin 2021 (=Gruberellidae Page & Blanton 1985), genera Orodruina (=Gruberella), Mombasina.[324]
      • Order Selenaionida Hanousková et al. 2018
        • Family Selenaionidae Hanousková et al. 2018, genus Selenaion.
    • Class Eutetramitea Pánek & Čepička 2025. Genera of uncertain position: Eltonia,[325] Euplaesiobystra, Fumarolamoeba, Heteramoeba, Parafumarolamoeba, Paravahlkampfia, Oramoeba, Stachyamoeba,[324] Vrihiamoeba.
      • Order Naegleriida Pánek & Čepička 2025 (=Heterolobosea sensu Cavalier-Smith 2022). Genera not assigned to any family: Aurem, Marinamoeba.
      • Order Percolomonadida Cavalier-Smith 1993
        • Family Barbeliidae Arndt 2023, genera Barbelia, Nonamonas.
        • Family Lulaidae Hohlfeld & Arndt 2023, genus Lula.
        • Family Percolomonadidae Cavalier-Smith 2003, genus Percolomonas.
      • Order Pseudociliatida Corliss & Lipscomb 1982
      • Order Creneida Cavalier-Smith 2022
        • Family Creneidae Pánek et al. 2014, genus Creneis.
      • Order Lyromonadida Cavalier-Smith 1993

Euglenozoa

The phylum Euglenozoa is home to at least 2,000 described species of single-celled flagellates of very dissimilar lifestyles. It was originally proposed to group the euglenids (such as the photosynthetic Euglena) and the kinetoplastids (like the pathogenic Trypanosoma), usually studied separatedly; eventually it included diplonemids and symbiontids as well.[328][329][330] Due to its share of photosynthetic species, traditionally regarded as algae, the phylum is also known as Euglenophyta by phycologists, and euglenids in particular were often studied as algae. Euglenids and kinetoplastids are the most diverse in terms of described species, although diplonemids may compose over 67,000 potential species.[330] The classification of euglenozoans was summarized by Cavalier-Smith in 2016.[329] A more phylogenetically precise revision of their classification was published in 2021 by Alexei Kostygov and coauthors,[330] with newer clades and genera described in the following years, particularly of euglenids. Still, one group of euglenids, the paraphyletic "ploeotids",[331] remains unresolved in the current classification, spread out across multiple clades.[332][333][334]

Phylum Euglenozoa (Euglenophyta) Cavalier-Smith 1981 emend. Simpson 1997

  • Class Euglenida Bütschli 1884 emend. Simpson 1997 (=Euglenoida Bütschli 1884 emend. Cavalier-Smith 1993). Genera not assigned to any lower clade: Moyeria,[335] Entosiphon. Genera incertae sedis: Gaulosia, Parastasiella, Dinemula, Paradinemula, Mononema, Ovicola, Embryocola, Copromonas.
    • Order Petalomonadida Cavalier-Smith 1993
      • Family Scytomonadidae Stein 1878, genera Atraktomonas, Michajlowastasia, Biundula, Calycimonas, Dolium, Dylakosoma, Notosolenus, Pentamonas, Petalomonas(P), Scytomonas, Tonotosolenus, Tropidoscyphus, Unotosolenus.
      • Family Sphenomonadidae Kent 1880, genus Sphenomonas.
    • Alistosa Lax & Simpson 2021. Genera not assigned to any family: Keelungia, Lentomonas, Decastava, Hokulea.[336]
      • Family Ploeotiidae Cavalier-Smith 2016, genera Ploeotia and Serpenomonas.
    • Karavia Lax, Cho & Keeling 2023, genera Hemiolia, Liburna.
    • Olkaspira Lax & Simpson 2021. Genera not assigned to any lower clade: Chelandium, Olkasia.
      • Spirocuta Cavalier-Smith, Chao & Vickerman 2016 (=Helicales Perschke et al. 2017). Genus incertae sedis: Heteronema.
        • Anisonemia Cavalier-Smith 2016
          • Order Anisonemida Cavalier-Smith 2016, family Anisonemidae Kent 1880 emend. Cavalier-Smith 2016, genera Anisonema, Dinema (=Dinematomonas).
          • Order Natomonadida Cavalier-Smith 2016
            • Suborder Metanemina, Cavalier-Smith 2016, family Neometanemidae Cavalier-Smith 2016, genus Neometanema.
            • Aphagea Cavalier-Smith 1993 emend. Busse & Preisfeld 2003 (=Rhabdomonadina Leedale 1967 emend. Cavalier-Smith 1993)
              • Family Astasiidae Kent 1884, genera Astasia, Gyropaigne, Menoidium, Parmidium, Rhabdomonas.
              • Family Distigmidae Hollande 1942, genus Distigma.
        • Order Peranemida (Peranematales) Cavalier-Smith 1993, family Peranemidae (Peranemataceae) Bütschli 1884, genera Chasmostoma, Jenningsia (=Peranemopsis),[337] Peranema, Urceolus (=Urceolopsis, Phialonema).[338][339]
        • Euglenophyceae Schoenichen in Eyfurth & Shoenichen 1925, emend. Marin & Melkonian 2003 (=Euglenea Butschli 1884, emend. Busse & Preisfeld 2002). Genera incertae sedis: Ascoglena, Euglenamorpha, Euglenopsis, Glenoclosterium, Hegneria, Klebsina, Euglenocapsa.
        • Subclass Acroglissia Cavalier-Smith 2016, order Acroglissida Cavalier-Smith 2016, family Teloproctidae Cavalier-Smith in Cavalier-Smith et al. 2016, genus Teloprocta.
  • Class Symbiontida Yubuki et al. 2009 (=Postgaardea Cavalier-Smith, 1998)
  • Subphylum Glycomonada Cavalier-Smith 2016
    • Class Diplonemea Cavalier-Smith 1993, order Diplonemida Cavalier-Smith 1993
      • Family Diplonemidae Cavalier-Smith 1993 emend. Adl et al. 2019, genera Diplonema, Rhynchopus, Lacrimia, Sulcionema, Flectonema.
      • Family Hemistasiidae Cavalier-Smith 2016 emend. Adl et al. 2019, genera Hemistasia, Namystinia, Artemidia.
      • Family Eupelagonemidae Okamoto & Keeling 2018, genus Eupelagonema.
    • Class Kinetoplastea Honigberg 1963 emend. Vickerman 1976. Genera incertae sedis: Bordnamonas, Cephalothamnium, Desmomonas, Jarrellia, Lamellasoma.
      • Subclass Prokinetoplastina Vickerman in Moreira et al. 2004, order Prokinetoplastida Vickerman in Moreira et al. 2004
      • Subclass Metakinetoplastina Vickerman in Moreira et al. 2004
        • Order Neobodonida Vickerman in Moreira et al. 2004
          • Suborder Neobodonina Cavalier-Smith 2016
          • Family Allobodonidae Goodwin et al. 2018,[343] genera Allobodo, Novijibodo.[344]
        • Order Parabodonida Vickerman in Moreira et al. 2004
          • Family Cryptobiidae Poche 1911 emend. Kostygov in Kostygov et al. 2021, genera Cryptobia, Parabodo.
          • Family Trypanoplasmatidae Hartmann & Chagas 1910 emend. Kostygov in Kostygov et al. 2021, genera Procryptobia, Trypanoplasma.
        • Order Eubodonida Vickerman in Moreira et al. 2004, family Bodonidae Bütschli 1883, genus Bodo.
        • Order Trypanosomatida Kent 1880 emend. Vickerman in Moreira et al. 2004, family Trypanosomatidae Dolfein 1901. Genera not assigned to subfamilies: Jaenimonas, Vickermania, Sergeia, Wallacemonas. Genera incertae sedis: Cercoplasma, Malacozoomonas, Nematodomonas, Rhynchoidomonas, Paleoleishmania G.Poinar & R.Poinar 2004.[345]
          • Subfamily Trypanosomatinae Doflein 1901, genus Trypanosoma.
          • Subfamily Leishmaniinae Maslov & Lukeš 2012
            • Infrafamily Crithidiatae Kostygov & Yurchenko 2017, genera Leptomonas, Crithidia, Lotmaria.
            • Infrafamily Leishmaniatae Maslov & Lukeš 2012, genera Leishmania, Porcisia, Endotrypanum, Novymonas Zelonia, Borovskyia.
          • Subfamily Herpetomonadinae Alexeieff 1911 stat. nov., emend. Kostygov & Yurchenko in Kostygov et al. 2021 (=Phytomonadinae Yurchenko, Kostygov, Votýpka & Lukeš 2015), genera Herpetomonas, Lafontella, Phytomonas.
          • Subfamily Strigomonadinae Votýpka et al. 2014, genera Angomonas, Strigomonas, Kentomonas.
          • Subfamily Blastocrithidiinae Votýpka, Yurchenko & Lukeš 2021, genera Blastocrithidia, Obscuromonas.
          • Subfamily Blechomonadinae Votýpka & Suková 2013, genus Blechomonas.
          • Subfamily Paratrypanosomatinae Votýpka & Lukeš 2013, genus Paratrypanosoma.

Minor clades

Ancyromonadida

  • Incertae sedis genus: Divimonas Barkhouse, Eglit, Weston & Simpson 2025[346]
  • Family Ancyromonadidae Cavalier-Smith 2008, genera Ancyromonas, Nutomonas.
  • Family Planomonadidae Cavalier-Smith 1993, genera Fabomonas, Planomonas.

CRuMs

Telonemia

The phylum Telonemia (telonemids) contains a few species of flagellates found in ocean and fresh waters worldwide. It was originally proposed in 2006 for Telonema, a genus of previously uncertain affinity.[349] Under the Cavalier-Smith system, telonemids were initially classified as a class of Cryptista,[138] but later analyses consistently recovered it as a separate group.[25] Until 2019, only two species had been formally described, each belonging to a separate genus,[350] but environmental DNA sequencing suggested there were many more species not yet described.[351] Between 2022 and 2025, eight additional species were described along with three new genera, bringing the total number of species to ten.[352][353][354]

Protists of uncertain affiliation

  • Family Acinetactidae Stokes 1886, genus Acinetactis.
  • Genera Actinocoma, Actinolophus, Adinomonas, Aletium, Amphimonas, Amylophagus, Aphelidiopsis, Asterocaelum, Asthmatos, Aurospora, Barbetia, Berkeleyaesol,[355] Belaria, Belonocystis, Bertarellia, Bertramia, Bodopsis, Boekelovia, Boveemonas,[226] Branchipocola, Camptoptyche, Chalarodora, Cibdelia, Cichkovia, Cinetidomyxa, Cingula, Cladomonas, Clathrella, Codonoeca, Coelosporidium,[z] Copromonas, Cyanomastix, Cyclomonas, Cytamoeba, Dallingeria, Dictyomyxa, Dimastigamoeba, "Dimorpha"[226], Dinemula, Dinoasteromonas, Diplocalium, Diplomita, Diplophysalis, Diploselmis, Dobellina, Ducelleria, Ectobiella, Elaeorhanis, Embryocola, Endemosarca, Endobiella, Endomonas, Endospora, Enteromyxa, Eperythrocytozoon, Errera, Fromentella, Gweamonas,[356] Gymnococcus, Gymnophrydium, Haematotractidium, Hartmannina, Heliobodo, Heliomonas, Hermisenella, Heterogromia, Hillea, Hyalodaktylethra, Immanoplasma, Isoselmis, Janickina, Kamera, Lagenidiopsis, Liegeosia, Luffisphaera,[aa] Lymphocytozoon, Lymphosporidium, Macappella, Magosphaera, Malpighiella, Martineziella, Megamoebomyxa, Microcometes, Monochrysis, Monodus, Mononema, Myrmicisporidium, Naupliicola, Nephrodinium, Neurosporidium, Orbulinella, Ovicola, Palisporomonas, Pansporella, Paradinemula, Paraluffisphaera, Paramonas, Paraplasma, Parastasia, Parastasiella, Peliainia, Peltomonas, Petasaria, Phagodinium, Phanerobia, Phloxamoeba, Phyllomitus, Phyllomonas, Physcosporidium, Pleuophrys, Pleuromastix, Protenterospora, Protomonas, Pseudoactiniscus, Pseudodimorpha,[357] Pseudosporopsis, Rhizomonas, Rhynchodinium, Rigidomastix, Schewiakoffia, Sergentella, Sphaerasuctans, Spongastericus, Spongocyclia, Stephanomonas, Strobilomonas, Thaulirens, Tetradimorpha, Topsentella, Toshiba, Trichonema, Urbanella.[6]

Incertae sedis within Diaphoretickes:

Incertae sedis within SAR:

  • Genus Labyrinthomyxa.[359]

See also

Notes

  1. The first eukaryotes were "neither plants, animals, nor fungi", hence as defined, the Protista would include the earliest common ancestor of all eukaryotes.
  2. In the original 4-kingdom model proposed in 1959, Protista included all unicellular microorganisms such as bacteria.
  3. The position of the genera Microcorycia, Parmulina, Penardochlamys and Zonomyxa, which were listed in 2002 under family Microcoryciidae, is not clear. They are placed here by morphological characters but this needs to be supported by molecular data.[6]
  4. The orders Thecamoebida, Dactylopodida, Acanthopodida, Himatismenida and Pellitida were initially divided into families, but phylogenetic analyses haven't supported the monophyly of each family. For this reason, in recent classifications there is no family rank division within it.[37][6]
  5. The genus Pessonella could be a synonym of Vannella.[6]
  6. The 2019 revision by the ISOP ignores the grouping of some variosean genera into higher rank clades (orders and families) proposed in older studies, due to the weakly supported SSU rRNA phylogenetic analyses.[6]
  7. According to a 2018 molecular study: "The genera Coriophyllum, Neohalosacciocolax and Pseudorhododiscus are currently assigned to the Palmariales but have yet to be included in a molecular phylogenetic context, and their associations within the Palmariales remain equivocal."[82]
  8. The picobiliphytes are phylogenetically closer to Rhodophyta and Rhodelphis than to other groups, and are therefore considered part of Archaeplastida.[92]
  9. The 2019 revision by the ISOP inaccurately stated that goniomonads are classified as "Cyathomonadacea Pringsheim 1944".[6] The name Cyathomonadacea does not exist; Pringsheim only described the family Cyathomonadaceae based on the genus Cyathomonas, and later the order Cyathomonadales and class Cyathomonadea were described, each by different authors. However, as pointed out in 1993 by Gianfranco Novarino and Ian Lucas, this genus was based on a species that actually belonged to Goniomonas; since then, taxonomists have prioritized higher taxa named after it (Goniomonadaceae, Goniomonadales/adida, Goniomonadea) instead.[139]
  10. The genus Tetragonidium is known only from one written diagnosis and some illustrations, and its affinities with cryptomonads are very uncertain.[139]
  11. Within the order Anoecida, the four families Anoecaceae, Caecitellaceae, Cafeteriaceae and Symbiomonadaceae were included by T. Cavalier-Smith in 2006. In a 2013 revision, he simplified the classification by transferring Symbiomonadaceae and Anoecaceae to Cafeteriaceae.[7] However, both of those families remain accepted by the scientific community as independent from Cafeteriaceae as of 2020.[156]
  12. O'Kelly placed the genera Antarctosaccion, Chrysomeris, Chrysonephos, Nematochrysis/Chrysowaernella, Phaeosaccion and Rhamnochrysis in the order Chrysomeridales nomen nudum in 1989,[174] and Cavalier-Smith placed it inside the class Chrysomeridophyceae (spelt originally as Chrysomerophycea) in 1995.[175] However, the class was proven to be polyphyletic. As a result, some of its genera (Nematochrysis/Chrysowaerella) were transferred to the class Chrysoparadoxophyceae, while others (Antarctosaccion and Phaeosaccion) were transferred to the class Phaeosacciophyceae. Due to a lack of molecular data, the placement of Chrysomeris, Chrysonephos and Rhamnochrysis remains unknown.[176]
  13. The position of Eustigmatophyceae is still unstable, with different phylogenetic methodologies showing affinities to either of the SI and SII clades.[178][179]
  14. The taxonomic ranks above class level (phylum, subphylum, infraphylum, etc.) are unstable within the Alveolata, due to the many different existing classifications. For example, the phylum-level rank has been traditionally assigned to Perkinsozoa,[190] Dinoflagellata, Chromerida and Apicomplexa, all of which have been classified as phylum Myzozoa,[191] which in turn has been classified inside phylum Miozoa.[182] Treating the four myzozoan groups as separate phyla is generally accepted among phycologists,[192] while at the same time the rejection of higher taxonomic ranks due to being superfluous is prevalent among protistologists.[6]
  15. Highly divergent 18S rRNA.[6] Since 2020 member of newly identified major apicomplexan subgroup Marosporida, putting together Aggregata octopiana Frenzel 1885, Merocystis kathae Dakin, 1911 (both Aggregatidae, originally coccidians), Rhytidocystis sp. 1 and Rhytidocystis sp. 2 Janouškovec et al. 2019 (Rhytidocystidae Levine, 1979, originally coccidians, Agamococcidiorida), and Margolisiella islandica Kristmundsson et al. 2011 (closely related to Rhytidocystidae)[194]
  16. Apart from morphological descriptions, no molecular analysis has solidly affiliated Rastrimonas with the Perkinsozoa.[201]
  17. The genera Parallobiopsis, Ellobiocystis and Rhizellobiopsis are only provisionally placed among ellobiopsids.[212]
  18. This taxon is artificial; many of the families listed in it are not monophyletic and have little support from phylogenetic analyses.[6]
  19. Whether Endomyxa is part of Cercozoa or not has been difficult to assess due to poor taxon sampling, but the most recent phylogenomic analyses support the inclusion of Endomyxa within Cercozoa.[217][220]
  20. The family Massisteriidae was originally placed in the order Leucodictyida, along with the family Leucodictyidae which included two genera Leucodictyon and Reticulamoeba. However, Leucodictyon has not been genetically sequenced[226] and Reticulamoeba is not closely related to Massisteriidae.[228]
  21. A proposed suborder-level clade by Cavalier-Smith in 2018 named Fiscullina[8] is not monophyletic because of uncultured tectofilosids.[236]
  22. There is only one molecular sequence from this genus, which causes long branches in gene phylogenies, and the node is unresolved.[6]
  23. According to Nakamura & Suzuki, the only extant (i.e. not extinct) orders of Polycystinea are Spumellaria, Nassellaria, Collodaria and Orodaria. Therefore, Entactinaria is considered an exclusively fossil group.[283]
  24. One 18S rRNA phylogenetic analysis suggests that the genus Opisthomitus is affiliated with the family Pyrsonymphidae.[300]
  25. Regarding the classification of Retortamonadida, there is a disconnect between the Cavalier-Smith system and the system described by different authors in the Handbook of the protists and other studies. The order Retortamonadida was originally defined as two genera: Chilomastix and Retortamonas. In 2013, Cavalier-Smith modified the retortamonads to only include Retortamonas, and describing a separate order Chilomastigida for Chilomastix only, placed among the early branching Carpediemonas-like organisms.[309] However, this has not yet been recognized by later studies from the other authors.[302][310][311]
  26. Probably a synonym of the zygomycete fungus Nephridiophaga.[6]
  27. May be the same genus as Belonocystis.[6]

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