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Stigonema

Generic name: STIGONEMA Agardh ex Bornet et Flahault, 1888. Ann. Sci. Nat. Bot., ser. 7, 5: 62.
Synonyms:
SIROSIPHON Kützing, 1843. Phycol. gener., p. 219.[ STIGONEMA Agardh, Systema Algar., p. XX, 1824 ex Bornet et Flahault: Conferva, Scytonema, Bangia, Sirosiphon, Hassalia, Hapalosiphon spec.]
STIGONEMA subg. SIROSIPHON Kützing ex Bornet et Flahault, 1888. Ann. Sci. Nat. Bot., ser. 7, 5:  67
Diagnosis:
Bornet et Flahault (1888): Fila libera, rarius lateraliter aggregata, in frondem definitam non concreta. Articuli filorum majorum e cellulis binis vel pluribus formati. Heterocystae saepius laterales, passim intercalares. Plantae terrestres, rigidae, atro-fuscae, vel aqua- ticae, pulvinatae, molliores. (Conf. Borzì, Morfologia e biologia delle Alghe ficocromacee, in N. Giorn. bot. ital., 1879, vol. XI, p.374.)
Type species: Stigonema mamillosum Agardh ex Bornet et Flahault 1888. - About 40 acceptable species; revision needed.
Descriptions:
Komárek (1992): Filamentous - thallous; thallus wooly or crusty, composed from free, coiled, true branched filaments, usually attached to the substrate, not diversified distinctly in basal filaments and branches. Trichomes two or multiseriate (only in young trichomes and at ends of branches uniseriate), sometimes very thick, irregularly laterally true branched (T- and V-type of branching), irregularly coiled, sometimes narrowed (with less number of cell rows) towards the ends, apical cell is
sometimes larger than the other ones. Sheaths thin or thick, limited, later wide, lamellated and usually yellowish-brown; around cells in old parts of filaments sometimes special envelopes (trichomes disintegrating in separated cells within filaments). Cells barrel-shaped or roundly irregular, connected usually by one pore ("pit connections") one with another, which disappear in some segments of trichomes; cell content blue-green or olive green, usually with prominent solitary granules. Heterocytes intercalar, solitary,
rarely lateral, in a similar form as neighbournig vegetative cells. Akinetes not known. Sometimes chroococcoid cell clusters arise.
Genotype differences, molecular data:
Reproduction strategies, life cycles, cell division:
Komárek (1992): Cells divide in all planes, but the crosswise fission is mostly common in trichomes. Meristematic zones occur only in sections, in which hormogonia arise. Reproduction by hormogonia, which liberate from the ends of trichomes and branches, morphologically different from trichomes (more cylindrical, uniseriate); hormogonia two- or more-celled, rarely many-celled.
Ultrastructure:
Taxonomic position, higher hierarchy: Cyanophyceae, Stigonematales, Stigonemataceae
Notes to taxonomy, misinterpretations:
Ecology, ecophysiology, ecological significance:
Komárek (1992): Stigonema-species occur in various biotopes allover the world, usually attached to the substrate or in soil, but not very common. More in tropical regions. Many species grow aerophytically or subaerophytically on bark of trees or wet rocks, from lowland to the alpine zone of high mountains (different species). Several species are known from pools, swamps and moors, where they grow in metaphyton or attached to stones and wood. Important are soil species in tropical habitats.
Physiology and biochemistry:
Distribution, endemism, problematic citations:
Reference strain:
Infrageneric scheme, species concept:
List of species:
Stigonema acroheterocystum H.X. Xiao 1991. Acta Phytotaxonomica Sinica 30(1): 95
Stigonema aerugineum Tilden 1910
Stigonema alpinum H.X. Xiao 2001. Acta Phytotaxonomica Sinica 39(1): 92
Stigonema anomalum F.N. Blanchard 1915. Rhodora 15: 194
Stigonema boliviense Bornet et Flahault 1888
Stigonema changbaiense H.X. Xiao 1991. Acta Phytotaxonomica Sinica 30(1): 96
Stigonema expansum Y.M. Lin et H.X. Xiao 2004. Journal of Wuhan Botanical Research 22(3): 207
Stigonema formosum Y.M. Lin et H.X. Xiao 2006
Stigonema fragile Y.M. Lin et H.X. Xiao 2004. Journal of Wuhan Botanical Research 22(2):117
Stigonema hormoides Bornet et Flahault 1888
Stigonema informe Kützing ex Bornet et Flahault 1888
Stigonema leprieurii Montagne ex Bornet et Flahault 1888
Stigonema mamillosum Agardh ex Bornet et Flahault 1888
Stigonema medium F.N. Blanchard 1915. Rhodora 15: 196

Stigonema minutum Hassall ex Bornet et Flahault 1888
Stigonema ocellatum Thuret ex Bornet et Flahault 1888
Stigonema panniforme Bornet et Flahault 1888
Stigonema pseudo-minutum Lin et Xiao 2006
Stigonema rosenvingii Böcher 1950. Meddelelser om Grønland 147(5): 6
Stigonema scrotiforme H.X. Xiao 1991. Acta Phytotaxonomica Sinica 30(1): 94
Stigonema sinuatum Lin et Xiao 2006
Stigonema turfaceum Cooke ex Bornet et Flahault 1888

Excludenda
Stigonema muscicola Borzì ex Bornet et Flahault 1888 = Fischerella muscicola
Stigonema tenue Bornet et Flahault 1888 = Fischerella tenuis
Stigonema thermale Borzì ex Bornet et Flahault 1888 = Fischerella thermalis

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

  2.1 taxonomy: Bornet & Flahault 1886, Frémy 1930, Geitler 1932, Geitler 1942, Desikachary 1959, Hoffmann 1986, Anagnostidis & Komárek 1990, Komárek 1992, Lin & Xiao 2006
  2.2 cytomorphology:
  2.3 16S rRNA sequencing:
  2.4 biology and life cycles:
  2.5 ecology: