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Hydrococcus

Generic name: HYDROCOCCUS Kützing, 1833, nom. cons. Linnaea 8: 380. [nomen conservandum]
Synonyms: ASKENASYA Möbius, 1887. Ber. Dtsch. Bot. Ges. 5: 56.
Diagnosis:
Type species: Hydrococcus rivularis Kützing 1833
Descriptions:
Komárek & Anagnostidis (1998): Cells grouped initially into unilayered, pseudoparenchymatous, nemato- or blas- toparenchymatous colonies, more or less circular in outline, covering the substrate (stones, plants), from which radially oriented rows of tightly packed cells grow on the margin; old colonies remain monolayered, or erect pseudofilaments (?) grow in the center, which are more or less parallel to one another, or form aggregates of clustered cells; pseudofilaments enveloped by thin, colourless sheaths; sheaths laterally confluent. The cells in old colonies form flattened layers up to hemispherical formations, or thin or thick, on the surface granular, black- green, black-brown or violet macroscopic mats. In old parts of the thallus are the cells or their groups (usually with 4-8 cells) more distant from one another, enveloped by their individual mucilaginous sheaths, sometimes even forming sarcinoid packets. Cells are spherical, oval, irregular or elongate at the ends of pseudofilaments, pale blue-green or olive-green, with more or less homogeneous content.
Komárek (1992): Unicellular - colonial; cells gathered firstly into unilayered , pseudoparenchymatous, nemato- or blastoparenchymatous, more or less circular colony covering the substrate (stones, plants), from which grow on the margin radially oriented, tightly gathered rows of cells; in old colonies develop erected pseuaofilaments. Pseudofilaments are situated parallely unbranched or later pseudodichotomously or pseudotetrachotomously divaricated, enveloped by thin, colourless sheaths; sheaths confluent together by their sides. Old colonies hemispherical, or forming thick, on the surface granular, black-green, black-brown or violet macroscopic mats. In old parts of thallus are the cells or their groups (usually with 4 or 8 cells) more separated, enveloped their own mucilaginous sheaths, sometimes forming even sarcinoid packets." Cells spherical, oval, irregular or elongated at the ends of pseudofilaments, pale blue-green or olive green, with more or less homogeneous content.
Genotype differences, molecular data:
Reproduction strategies, life cycles, cell division:
Komárek & Anagnostidis (1998): Cell division in various planes in successive cell cycles, but the crosswise binary fission prevails in marginal parts or in surface layers of colonies. Typical nanocytes not observed. Reproduction by solitary cells or by small clusters of cells. Not a well known genus, almost all the species must be revised; data about Hydrococcus from saline waters and mineral lakes are still uncertain.
Komárek (1992): Cell division in different planes in successive cell cycles, in marginal or erected rows prevails the cross-wise binary fission. Typical nanocytes not observed. Reproduction by solitary cells or by small clusters of cells.
Ultrastructure:
Taxonomic position, higher hierarchy:
Cyanophyceae, Chroococcales, Hydrococcaceae
Notes to taxonomy, misinterpretations:
Ecology, ecophysiology, ecological significance:
Komárek (1992): Type species known from stones, plants and wooden substrates in rapid floating, cold streams, mainly in mountains, probably with cosmopolitan distribution (however, this species is still little known and the identity of populations from different countries must be revised). Three other species (very little known, sometimes only from one locality) have similar ecology, one species was described from the littoral of lakes. Data of Hydrococcus from salinic waters and mineral lakes are uncertain.
Physiology and biochemistry:
Distribution, endemism, problematic citations:
Reference strain:
Infrageneric scheme, species concept:
List of species:
Hydrococcus cesatii Rabenhorst 1860
Hydrococcus rivularis Kützing 1833

Unclear taxa:
Hydrococcus marinus Grunow 1861
Hydrococcus ulvaceus Kützing 1843

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

  2.1 taxonomy: Geitler 1932, Geitler 1942, Komárek 1992, Komárek & Anagnostidis 1998
  2.2 cytomorphology:
  2.3 16S rRNA sequencing:
  2.4 biology and life cycles:
  2.5 ecology: