Chlorarachniophyte

The chlorarachniophytes are a small group of exclusively marine cercozoans widely distributed in tropical and temperate waters.^[6] They are typically mixotrophic, ingesting bacteria and smaller protists as well as conducting photosynthesis. Normally they have the form of small amoebae, with branching cytoplasmic extensions that capture prey and connect the cells together, forming a net. These extensions are dependent on the presence of light and polymerization of the actincytoskeleton.^[7] They may also form flagellatezoospores, which characteristically have a single subapical flagellum that spirals backwards around the cell body, and walled coccoid cells.

The chloroplasts were presumably acquired by ingesting some green alga.^[8] They are surrounded by four membranes, the outermost of which is continuous with the endoplasmic reticulum, and contain a small nucleomorph between the middle two, which is a remnant of the alga's nucleus. This contains a small amount of DNA and divides without forming a mitotic spindle. The origin of the chloroplasts from green algae is supported by their pigmentation, which includes chlorophyllsa and b, and by genetic similarities. The only other groups of algae other than chlorarachnids contain nucleomorphs are a few species of dinoflagellates, which also have plastids originating from green algae,^[9] and the cryptomonads, which acquired their chloroplasts from a red alga.

The chlorarachniophytes only include five genera, which show some variation in their life-cycles and may lack one or two of the stages described above. Genetic studies place them among the Cercozoa, a diverse group of amoeboid and amoeboid-like protozoa.

The chlorarachniophytes were placed before in the order Rhizochloridales, class Xanthophyceae (e.g., Smith, 1938), as algae, or in order Rhizochloridea, class Xanthomonadina (e.g., Deflandre, 1956), as protozoa.

So far sexual reproduction has only been reported in two species; Chlorarachnion reptans and Cryptochlora perforans.^[6]

Based on Shiratori et al. 2024.^[3]

• Class ChlorarachneaHibberd & Norris 1984^[10] [Chlorarachnea Cavalier-Smith 1998; Chlorarachniophyta Hibberd & Norris 1984; Chlorarachnia Cavalier-Smith 1993]
  • Order ChlorarachnidaIshida et al. 1996 [Chlorarachniida Hibberd & Norris 1984]
    • Family ChlorarachniidaeIshida et al. 1996
      • Genus BigelowiellaMoestrup 2001
        • Species B. longifilaShuhei, Kunihiko & Kenichiro 2007
        • Species B. natansMoestrup 2001
      • Genus ChlorarachnionGeitler 1930
        • Species Chlorarachnion reptansGeitler 1930
      • Genus NorrisiellaOta, Ueda & Ishida 2007
        • Species Norrisiella sphaericaOta, Ueda & Ishida 2007
      • Genus PartenskyellaOta et al. 2009
        • Species Partenskyella glossopodiaOta et al. 2009
    • Genus CryptochloraCalderon-Saenz & Schnetter 1987
      • Species Cryptochlora perforansCalderon-Saenz & Schnetter 1987
    • Family GymnochloridaeCavalier-Smith 2018
      • Genus GymnochloraIshida et al. 1996
        • Species G. dimorphaOta 2011
        • Species G. stellataIshida et al. 1996
      • Genus AmorphochloraIshida, Yabuki & Ota 2011
        • Species Amorphochlora amoebiformis(Ishida & Hara 1996) Ishida, Yabuki & Ota 2011 [Lotharella amoeboformisIshida & Hara 1996]
      • Genus ViridiuvalisT.Shiratori, S.Fujita, T.Shimizu & K.Ishida 2017^[11]
        • Species Viridiuvalis adhaerensT.Shiratori, S.Fujita, T.Shimizu & K.Ishida 2017
    • Family LotharellidaeCavalier-Smith 2018
      • Genus LotharellaIshida et al. 1996
        • Species L. scrobicolataIshida & Hara
        • Species L. polymorphaDietz et al. 2003
        • Species L. vacuolataOta & Ishida 2005
        • Species L. oceanicaOta 2009
        • Species L. reticulosaOhta 2012
        • Species L. globosa(Ishida & Hara 1994) Ishida et al. 1996 [Chlorarachnion globosumIshida & Hara 1994]
  • Order MinorisidaCavalier-Smith 2018^[12]
    • Family MinorisidaeCavalier-Smith 2018
      • Genus MinorisaDel Campo 2013
        • Species Minorisa minutaDel Campo 2013
  • Incertae sedis
    • Genus RhabdamoebaDunkerly 1921^[13][3]
      • Species Rhabdamoeba marinaDunkerly 1921

• 
  Lotharella globosa extending a filopodium (Fp) through a pore of the cell wall (CW) from a walled amoeboid cell. Py: pyrenoid.Scale bar = 10 μm
• 
  Binary and quaternary cell divisions of Lotharella globosa. Arrowheads indicate the parental cell wall.Scale bar = 10 μm
• 
  Flagellate cell of Lotharella globosa with a single flagellum (Fl) and plastid (P)Scale bar = 10 μm

• AlgaeBase: Chlorarachniophyta
• Biología sistemática: Chlorarachniophyta
• Biología sistemática: Cercozoa Archivado el 2 de abril de 2015 en Wayback Machine
• Tree of Life: Chlorarachniophyta