Culture Strains of a Chlorarachniophyte, Lotharella globosa

The chlorarachniophytes are a small group of exclusively marine algae widely distributed in tropical and temperate waters. 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. They may also form

flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and their ...

zoospores, which characteristically have a single subapical flagellum that spirals backwards around the cell body, and walled coccoid cells. The

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

s were presumably acquired by ingesting some green alga. They are surrounded by four membranes, the outermost of which is continuous with the

endoplasmic reticulum The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough 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

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

s ''a'' and ''b'', and by genetic similarities. The only other group of algae that contain nucleomorphs are the cryptomonads, but their chloroplasts seem to be derived 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 Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead defined by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major eu ...

, 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.

Phylogeny

Based on the work of Hirakawa et al. 2011.

Taxonomy

* Class Chlorarachniophyceae Hibberd & Norris 1984 hlorarachnea Cavalier-Smith 1998; Chlorarachniophyta Hibberd & Norris 1984; Chlorarachnia Cavalier-Smith 1993** Order Minorisida Cavalier-Smith 2017 *** Family Minorisidae Cavalier-Smith 2017 **** Genus ''

Minorisa ''Minorisa'' is a monotypic genus of marine heterotrophic flagellates that is heavily featured in the eukaryotic picoplankton of coastal ecosystems. It is part of the supergroup Rhizaria, at the base of the class Chlorarachniophyceae. Etymol ...

'' Del Campo 2013 ***** Species ''

Minorisa minuta ''Minorisa'' is a monotypic genus of marine heterotrophic flagellates that is heavily featured in the eukaryotic picoplankton of coastal ecosystems. It is part of the supergroup Rhizaria, at the base of the class Chlorarachniophyceae. Etymol ...

'' Del Campo 2013 ** Order Chlorarachniales Ishida & Hara 1996 hlorarachniida Hibberd & Norris 1984*** Family Chlorarachniaceae (Pascher 1939) Ishida & Hara 1996 **** Genus '' Amorphochlora'' Ishida, Yabuki & Ota 2011 ***** Species '' Amorphochlora amoebiformis'' (Ishida & Hara 1996) Ishida, Yabuki & Ota 2011 'Lotharella amoeboformis'' Ishida & Hara 1996**** Genus ''

Bigelowiella ''Bigelowiella'' is a genus of chlorarachniophyte algae, containing a secondary plastid within a reduced cytoplasmic compartment that contains a vestigial nucleomorph. Genomes The ''Bigelowiella natans'' nuclear genome was the first to be sequen ...

'' Moestrup 2001 ***** Species '' B. longifila'' Shuhei, Kunihiko & Kenichiro 2007 ***** Species '' B. natans'' Moestrup 2001 **** Genus ''

Chlorarachnion The chlorarachniophytes are a small group of exclusively marine algae widely distributed in tropical and temperate waters. They are typically mixotrophic, ingesting bacteria and smaller protists as well as conducting photosynthesis. Normally the ...

'' Geitler 1930 ***** Species '' Chlorarachnion reptans'' Geitler 1930 **** Genus ''

Cryptochlora The chlorarachniophytes are a small group of exclusively marine algae widely distributed in tropical and temperate waters. They are typically mixotrophic, ingesting bacteria and smaller protists as well as conducting photosynthesis. Normally the ...

'' Calderon-Saenz & Schnetter 1987 ***** Species ''

Cryptochlora perforans The chlorarachniophytes are a small group of exclusively marine algae widely distributed in tropical and temperate waters. They are typically mixotrophic, ingesting bacteria and smaller protists as well as conducting photosynthesis. Normally the ...

'' Calderon-Saenz & Schnetter 1987 **** Genus ''

Gymnochlora The chlorarachniophytes are a small group of exclusively marine algae widely distributed in tropical and temperate waters. They are typically mixotrophic, ingesting bacteria and smaller protists as well as conducting photosynthesis. Normally the ...

'' Ishida, Nakayama & Hara 1996 ***** Species '' G. dimorpha'' Ota 2011 ***** Species '' G. stellata'' Ishida, Nakayama & Hara 1996 **** Genus '' Lotharella'' Ishida & Hara 1996 ***** Species '' L. scrobicolata'' Ishida & Hara ***** Species '' L. polymorpha'' Dietz et al. 2003 ***** Species '' L. vacuolata'' Ota & Ishida 2005 ***** Species '' L. oceanica'' Ota 2009 ***** Species '' L. reticulosa'' Ohta 2012 ***** Species '' L. globosa'' (Ishida & Hara 1994) Ishida & Hara 1996 'Chlorarachnion globosum'' Ishida & Hara 1994**** Genus '' Norrisiella'' Ota, Ueda & Ishida 2007 ***** Species '' Norrisiella sphaerica'' Ota, Ueda & Ishida 2007 **** Genus '' Partenskyella'' Ota et al. 2009 ***** Species '' Partenskyella glossopodia'' Ota et al. 2009 File:Chlorarachniophyte, Lotharella globosa, extending a filopodium.png, ''Lotharella globosa'' extending a filopodium (Fp) through a pore of the cell wall (CW) from a walled amoeboid cell. Py: pyrenoid.
Scale bar = 10µm File:Binary and quaternary cell divisions of a chlorarachniophyte, Lotharella globosa.png, Binary and quaternary cell divisions of ''Lotharella globosa''. Arrowheads indicate the parental cell wall.
Scale bar = 10µm File:Flagellate cell of a chlorarachniophyte, Lotharella globosa, with a single flagellum and plastid.png, Flagellate cell of ''Lotharella globosa'' with a single flagellum (Fl) and plastid (P)
Scale bar = 10µm

References

External links

AlgaeBase: ChlorarachniophytaTree of Life: Chlorarachniophyta
{{Taxonbar, from=Q136146 Filosa Algal taxonomy