A cultured chlorarachniophyte,Lotharella globosa LEX01 strain[2]
Thechlorarachniophytes are a small group of exclusively marinealgae widely distributed in tropical and temperate waters.[3] They are typicallymixotrophic, ingestingbacteria and smallerprotists as well as conductingphotosynthesis. Normally they have the form of smallamoebae, with branching cytoplasmic extensions that capture prey and connect the cells together, forming a net. These extensions are dependent on the presence oflight and polymerization of theactincytoskeleton.[4] They may also formflagellatezoospores, which characteristically have a single subapical flagellum that spirals backwards around the cell body, and walled coccoid cells.
Thechloroplasts were presumably acquired by ingesting somegreen alga.[5] They are surrounded by four membranes, the outermost of which is continuous with theendoplasmic reticulum, and contain a smallnucleomorph between the middle two, which is a remnant of the alga's nucleus. This contains a small amount ofDNA and divides without forming amitotic spindle. The origin of the chloroplasts from green algae is supported by their pigmentation, which includeschlorophyllsa andb, and by genetic similarities. The only other groups of algae that contain nucleomorphs are a few species ofdinoflagellates, which also have plastids originating from green algae,[6] and thecryptomonads, which acquired their chloroplasts from ared 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 theCercozoa, a diverse group of amoeboid and amoeboid-like[clarification needed] protozoa.
The chlorarachniophytes were placed before in the order Rhizochloridales, classXanthophyceae (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 andCryptochlora perforans.[3]
^Hibberd, David J.; Norris, Richard E. (1984). "Cytology and ultrastructure ofChlorarachnion reptans (Chlorarchniophyta Divisio nova, Chlorachniophyceae Classis nova)".Journal of Phycology.20 (2):310–330.doi:10.1111/j.0022-3646.1984.00310.x.S2CID86059445.
^abShiratori, Takashi; Ishida, Ken-ichiro (March 2024). "Rhabdamoeba marina is a heterotrophic relative of chlorarachnid algae".Journal of Eukaryotic Microbiology.71 (2) e13010.doi:10.1111/jeu.13010.PMID37941507.
^Rogerson, Andrew; Hannah, Fiona J.; Anderson, O. Roger (1998). "A Redescription ofRhabdamoeba marina, an Inconspicuous Marine Amoeba from Benthic Sediments".Invertebrate Biology.117 (4): 261.doi:10.2307/3227028.JSTOR3227028.
^Cavalier-Smith (2017), "Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences",Protoplasma,255 (1):297–357,doi:10.1007/s00709-017-1147-3,PMC5756292,PMID28875267
^Guiry, M.D.; Guiry, G.M."Viridiuvalis".AlgaeBase. Retrieved24 April 2024.
