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Isocystis

Generic name: ISOCYSTIS Borzì ex Bornet et Flahault 1888. Ann. Sci. Nat. Bot., ser. 7, 7: 261.[ISOCYSTIS Borzi, Morfologia e biologia delle Alghe ficocromacee in N. Giornale bot. ital., vol. X, p. 278, 1878; Nachtrage zur Morphologie und Biologie der Nostochaceen, in Flora, 1878, n. 30, p. 468]
Synonyms: PSEUDONOSTOC Elenkin, 1949. Monogr. Alg. Cyanoph. URSS, pars spec. 2: 1225.
Diagnosis:
Bornet et Flahault (1888): Thallus parvus aut minimus, laete caeruleus vel dilute aerugineo-olivascens, submembranaceo-lubricus. Trichomata tenerrima (4-5 λm crassa) recta, apices versus sensim attenuata, paralleliter decurrentia, fasciculatim et densissime congregata, articulis elliptico aut sphaerico-compressis, arcte et saepe oblique connexis, plerumque mutua pressione angulosis. Sporae exacte globosae, cellulis vegetativis duplo majores, aureo-fuscae, exosporio crasso, subtiliter granulato-scabro.
Type species: Isocystis messanensis Borzì ex Barnet et Flahault 1888. 
Descriptions:
Komárek (1992): Filamentous; filaments solitary, in small,microscopic fascicles or in formless, microscopic, gelatinous colonies, attached to the substrate, in metaphyton or free floating, with fine, diffluent, structureless, colourless, sometimes hardly visible gelatinous envelopes. Trichomes uniserial, simple curved or coiled, isopolar, usually slightly narrowed to both ends, clearly constricted at cross walls. Cells barrel-shaped, isodiametrical or longer or shorter than wide, sometimes with solitary granules within cells. Heterocytes missing. Akinetes arise in rows, more or less in the middle of tricho- mes (apoheterocytic orimin), a little larger than vegetative cells, with thick cell walls.
Genotype differences, molecular data:
Reproduction strategies, life cycles, cell division:
Komárek (1992): All cells capable to divide, cell division crosswise, perpendicularly to the trichome axis. Reproduction by short hormogonia (sometimes disintegrating up into solitary cells) and by akinetes.
Ultrastructure:
Taxonomic position, higher hierarchy: Cyanophyceae,
Nostocales, Nostocaceae, Nostocoideae
Notes to taxonomy, misinterpretations:
Ecology, ecophysiology, ecological significance:
Komárek (1992): One species grows subaerophytic on wet walls, several are periphytic in different freshwater biotopes (springs, littorals of stagnant water), one species is planktic, one was described from soil.
Physiology and biochemistry:
Distribution, endemism, problematic citations:
Reference strain:
Infrageneric scheme, species
concept:

List of species:
Isocystis halobia Anagnostidis et Roussomoustakaki 1991. Archiv für Hydrobiologie/Algological Studies 64: 307
Isocystis infusionum (Kützing) Borzì ex Bornet et Flahault 1888
Isocystis messanensis Borzì ex Bornet et Flahault 1888. Ann. Sci. Nat. Bot., ser. VII, 7: 262
Isocystis planctonica Starmach 1962
Isocystis salina Ivanova in Berg et Ignatov 1901

Unclear taxa:
Isocystis andalusica Gonzales-Guerrero 1946
Isocystis major Weber van Bosse 1913
Isocystis minutissima (Kützing ex Bornet et Flahault) Komárek et Anagnostidis 1989
Isocystis moniliformis Borzì ex Bornet et Flahault 1888
Isocystis pallida Voronichin 1927
Isocystis richteri (Elenkin) Komárek et Anagnostidis 1989
Isocystis spermosiroides Borzì ex Bornet et Flahault 1888
Pseudanabaena edaphyca Melnikova 1953

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

  2.1 taxonomy: Geitler 1932, Geitler 1942, Hollerbach et al. 1953, Starmach 1966, Komárek & Anagnostidis 1989, Komárek 1992
  2.2 cytomorphology:
  2.3 16S rRNA sequencing:
  2.4 biology and life cycles:
  2.5 ecology: