Calothrix C.ex & Flahault, 1886
Lectotype species: Calothrix confervicola C.Agardh ex Bornet & Flahault
Original publication:Bornet, É. & Flahault, C. (1886). Revision des Nostocacées hétérocystées contenues dans les principaux herbiers de France. Annales des Sciences Naturelles, Botanique, Septième série 3: 323-381.
Type designated in Geitler, L. (1942). Schizophyta: Klasse Schizophyceae. In: Die natürlichen Pflanzenfamilien, Sweite Auflage. (Engler, A. & Prantl, K. Eds) Vol.1b, pp. 1-232. Leipzig: Wilhelm Engelmann.
Taxonomic status: currently recognized as a distinct genus.
Gender: This genus name is currently treated as feminine.
Most recent taxonomic treatment adopted: Komárek, J., Kastovsky, J., Mares, J. & Johansen, J.R. (2014). Taxonomic classification of cyanoprokaryotes (cyanobacterial genera) 2014, using a polyphasic approach. Preslia 86: 295-335.
Description: Filaments heteropolar, differentiated into basal (usually joined to the substrate) and apical parts, simple, solitary or in small groups, separated one from another (not in common mucilage), rarely with single, lateral false branches, oriented more or less in direction of the original growth; the filaments sometimes creeping on the substrate. Trichomes always with basal, more or less spherical or hemispherical heterocytes, and occasionally with intercalary cylindrical heterocytes; at intercalary heterocytes sometimes division of trichomes and their subsequent dissociation; trichomes sometimes with widened basal part, constricted or unconstricted at the crosswalls, ending by the hair-like apical part composed from narrow, long, hyaline cells; the hair formation is dependent on phosphorus-metabolism; (trichomes in several species obligatory without hairs - they represent probably a special genus different from both Calothrix and Microchaete). Sheaths always present, usually firm, sometimes lamellated and yellow-brownish colored, or funnel-shaped widened at the ends; cells cylindrical or barrel-shaped. Aerotopes in vegetative cells absent, but occur in hormogonia (always ?). Akinetes rarely in basal parts (known in few species only). Probably capable of chromatic adaptation (all species ?). Cell division perpendicularly to the long axis of trichomes (probably always with subapical meristematic zones). Trichomes dissociate at heterocytes and separately develop into new trichomes. Reproduction by motile hormogonia, which divide from the trichome, but help of the necridic cells and liberate from the sheath after separation of the terminal hair; hormogonia of several species with aerotopes (in all species ?; maybe an intergeneric feature). Only periphytic species, growing on aquatic plants, other algae, on stones and wooden substrates in different aquatic habitats, particularly in unpolluted habitats. Several species known from the marine littoral (inc. type species).
Information contributed by: J. Komárek. The most recent alteration to this page was made on 17 Feb 2020 by M.D. Guiry.
Numbers of names and species: There are 222 species names in the database at present, as well as 52 infraspecific names. Of the species names, 141 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..
Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):
Click here to also show infraspecific names in the list below.
Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.
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.
Created: 28 December 2000 by M.D. Guiry
Verified by: 02 November 2017 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43089
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 17 May 2021.