Schizothrix Kützing ex Gomont, 1892

Holotype species: Schizothrix fuscescens Kutzing ex Gomont

Original publication and holotype designation: Gomont, M. (1892). Monographie des Oscillariées (Nostocacées homocystées). Annales des Sciences Naturelles, Botanique, Série 7 15: 263-368, pls 6-14 [VI-XIV in text and expl. pl.].

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Description: Filamentous-colonial; filaments polarized, thick, containing rarely one, usually several more or less parallel situated trichomes; sheaths fine, slightly or clearly widened, gelatinous, homogeneous, rarely layered or lamellated, with straight or irregularly wavy, limited margin; sometimes fine special sheaths enveloping the simple trichomes occur; sheaths colorless or partly colored, yellow, yellowish-brown, reddish or blue-violet; ends of sheaths characteristically narrowed and bluntly pointed, usually closed, sometimes branched. Filaments in free divaricated, microscopic or to macroscopic filamentous thallus (subg. Schizothrix), joined in erect fascicles (subg. Symplocastrum Gomont 1892), or incrusted heavily by calcium carbonate and forming more or less hard, hemispherical or layered colonies on the (usually stony) substrate (subg. Inactis (Kützing) Gomont l892).

Information contributed by: J. Komárek. The most recent alteration to this page was made on 2018-08-16 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Gender: This genus name is currently treated as feminine.

Most recent taxonomic treatment adopted: Mai, T., Johansen, J.R., Pietrasiak, N., Bohunická, M. & Martin, M.P. (2018). Revision of the Synechococcales (Cyanobacteria) through recognition of four families including Oculatellaceae fam. nov. and Trichocoleaceae fam. nov. and six new genera containing 14 species. Phytotaxa 365(1): 1-59, 23 figs.

Comments: Thallus usually joined to the substrate, rarely free (in soil or metaphyton). Trichomes cylindrical, isopolar, not polarized (in contrast to filaments !), usually not attenuated to the ends, unconstricted or slightly constricted at the crosswalls. Cells cylindrical, rarely more or less isodiametric, usually longer than wide; apical cells mainly conical and rounded, without calyptra and without thickened outer cell wall. Heterocytes and akinetes missing. Cell division crosswise to the trichome axis, without meristematic zone; all cells capable of division. Reproduction by motile hormogonia, which separate from trichomes probably without help of necridic cells. The species are usually classified into several subgenera or sections, from which two (Symplocastrum and Inactis) represent probably special genera; the section "Chromosiphon" is without taxonomic value. Many species grow in littoral of lakes joined to the stony or wooden substrates (usually in surf zone) or in metaphyton among aquatic plants and in moors and swamps. Characteristic are the Inactis-species, forming crusty hemispherical colonies or layers on stones and rocks in littoral zone of lakes, streaming water or on wet rocks, usually in limestone areas. Several species are known from sea coasts and salty biotopes, others live in springs, mineral and thermal springs or in waterfalls. Aerophytic species grow also in wet soils, often in moors. Several representatives of the subg. Symplocastrum form characteristic mats with erect Symploca-like fascicles on wet, unpolluted forest soils or old wooden substrates. The species from the section Hypheothrix (Kützing) Lemmermann belong probably to the genus Phormidium.

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Contributors
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=43075

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 16 August 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 04 February 2023

 
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