Holotype species: Xenococcus schousboei Thuret
Original publication and holotype designation: Bornet, É. & Thuret, G. (1880). Notes algologiques recueil d'observations sur les algues. Fasc. 2. pp. 73-196, pls XXVI-L. Paris: G. Masson.
Taxonomic status: currently recognized as a distinct genus.
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: Unicellular-colonial; colonies attached to the substrate, flat to pseudoparenchymatous, circular or elongated in outline, 1-3(4)-layered, microscopic, later to macroscopically visible (point-like), composed of very densely agglomerated cells. Cells more or less oval, irregular, polygonal with rounded corners, or in the upper layer of a colony slightly pyriform, enveloped by colorless, thin, firm, usually slightly layered, tight, mucilaginous sheath; cell content blue-green, greyish or reddish. Division of cells irregular, in more directions perpendicular to the substrate, but later also crosswise (parallel to the substrate); cells do not grow into original shape before the next division. From cells in the upper part of a colony arise sometimes nanocytes, which serve mainly to the reproduction.
Information contributed by: J. Komárek. The most recent alteration to this page was made on 6 Mar 2015 by M.D. Guiry.
Comments: Attached to different substrates (stones, algae, water plants) in different water biotopes; several species are known from alpine streams, another one from the marine littoral. Many species have probably the special areas of distribution. A poorly known genus.
Numbers of names and species: There are 38 species names in the database at present, as well as 5 infraspecific names. Of the species names, 30 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.
Komárek, J. (2003). Coccoid and colonial cyanobacteria. In: Freshwater Algae of North America. Ecology and Classification. (Wehr, J.D. & Sheath, R.G. Eds), pp. 59-116. Amsterdam Boston London New York Oxford Paris San Diego San Fransisco Singapore Sydney Tokyo: Academic Press.
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: 06 March 2015 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43073
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 12 April 2021.