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Snowella

Generic name: SNOWELLA Elenkin, 1938. Monogr. Algarum Cyanophyc., Pars Spec., 1: 278.
Synonyms:
Diagnosis:
Type species: Snowella rosea (Snow) Elenkin 1938.
Descriptions:
Komárek (2003): Snowella comprises free-living, spherical or oval microscopic colonies, sometimes composed of subcolonies, that have a central system of thin, nearly pseudodichotomously divided gelatinous stalks (may be confluent) that bear cells at their ends (periphery of colony). Colonies are enveloped by very fine, unstructured, and diffuse mucilage. Cells are spherical or slightly radially elongated, and pale blue-green, olive green, or
yellowish in color; one species may be pinkish. Two species have one or a few central aero-topes. The cells are 0.6-4.2 μm in diameter (or long). Cell division is by binary fission in two planes, perpendicular to one another and to the colonial surface. Reproduction is by disintegration of colonies.
Komárek & Anagnostidis (1998): Colonies more or less spherical or irregularly oval, rarely compound, free floating, with distinct or indistinct (staining !), homogeneous, colourless and wide mucilaginous envelopes. Within colonies there is a more or less stable system of fine, thin, thread-like mucilaginous stalks radiating from the colonial center, more or less pseudodichotomously divaricated and sometimes fasciculate, widened in the center. Cells spherical or slightly elongate, joined to the ends of stalks during the whole life cycle, distant from one another. If the cells are densely disposed on the periphery of old multicellular colonies, there always remain at least narrow spaces between them; cells usually not strictly in one peripheral layer, but slightly radially shifted from one another.
Komárek (1992): Unicellular - colonial; colonies microscopic, +/- spherical or irregularly oval, rarely composed, free living (floating), with indistinct, smooth, colourless, fine and wide mucilaginous envelopes;
within the colonies a system of fine, thin (thread-like), +/- stable, mucilaginous, +/- pseudodichotomously branched and sometimes fasciculating stalks, which are sometimes widened in the centre. Cells spherical or slightly radially
elongated, joined to the ends of stalks during almost the whole life cycle, distant from one another, sometimes slightly radially shifted to one another (if the cells are densely disposed in old colonies, always remain at least narrow spaces between them); cells pale greyish blue-green, yellowish or pinkish, without or with solitary central aerotopes (granules ?).
Genotype differences, molecular data:
Reproduction strategies, life cycles, cell division:
Komárek (1992): Cell division in two directions in successive generations, perpendicular to each other and to the surface of a colony; soon after division the cells separate one from another in distant positions. The colonies disintegrate into small cell groups up to solitary cells.
Ultrastructure:
Taxonomic position, higher hierarchy: Cyanophyceae,
Chroococcales, Merismopediaceae, Gomphosphaerioideae
Notes to taxonomy, misinterpretations:
Ecology, ecophysiology, ecological significance:
Komárek (2003): Seven species are known from the plankton of temperate fresh and brackish waters, particularly from cold, northern, mesotrophic lakes (Komarek and Anagnostidis, 1998).
Komárek & Anagnostidis (1998): Cell division only by binary fission in two planes in successive generations, perpendicular to one another and to the colony surface; disintegration of colonies even into solitary cells.
Komárek (1992): Freshwater (or in slight brackish biotopes), mainy in plankton of large, slightly eutrophized reservoirs, rarely secondary in metaphyton. Several species are known only from limited areas (1 from
North-American large lakes, 2 from northern regions of N temperated zone, 1 from Alpine lakes), two species possess probably +/- world-wide distribution (S. litoralis, S. lacustris).
Physiology and biochemistry:
Distribution, endemism, problematic citations:
Reference strain:
Infrageneric scheme, species concept:
List of species:
Snowella arachnoidea Komárek et Hindák 1988
Snowella atomus Komárek et Hindák 1988
Snowella fennica Komárek et Komárková-Legnerová 1992
Snowella lacustris (Chodat) Komárek et Hindák 1988
Snowella litoralis (Häyrén) Komárek et Hindák 1988
Snowella rosea (Snow) Elenkin 1938
Snowella septentrionalis Komárek et Hindák 1988

Unclear taxa:
Woronichinia problematica Joosten 2006

Keys:
List of stains:
Drawings:
Komárek 1992
Application technology:
Literature:

  2.1 taxonomy: Smith 1920, Geitler 1932, Elenkin 1938, Hollerbach et al. 1953, Komárek & Anagnostidis 1986, Komárek & Hindák 1987, Komárek & Hindák 1988, Komárek & Komárkova 1992, Komárek 1992, Komárek & Anagnostidis 1998, Komárek 2003
  2.2 cytomorphology:
  2.3 16S rRNA sequencing:
  2.4 biology and life cycles:
  2.5 ecology: