Desmidium C.ex , 1848
Lectotype species: Desmidium swartzii C.Agardh ex Ralfs
Original publication:Ralfs, J. (1848). The British Desmidieae. pp. [i]-xxii, [i], -226, pls I-XXXV. London: Reeve, Benham & Reeve.
Type designated in Nägeli, C. (1849). Gattungen einzelliger Algen, physiologisch und systematisch bearbeitet. Neue Denkschriften der Allg. Schweizerischen Gesellschaft für die Gesammten Naturwissenschaften 10(7): i-viii, 1-139, pls I-VIII.
Taxonomic status: currently recognized as a distinct genus.
Most recent taxonomic treatment adopted: Guiry, M.D. (2013). Taxonomy and nomenclature of the Conjugatophyceae (=Zygnematophyceae). Algae. An International Journal of Algal Research 28: 1-29.
Description: Cells longer or shorter than broad, with distinct or indistinct median constriction (isthmus) where semicell walls overlap. Cells united into long filaments, either by entire apical surface of adjacent cells or by apical processes. Cells 3-5 angled or elliptical in apical view. Cell angles usually slightly offset on each semicell, producing helical pattern of angles along filament. Cell wall smooth with pores in transverse rows or scattered. One chloroplast per semicell, stellate in end view, with central pyrenoid, or with pyrenoid in each lobe. Nucleus at isthmus between chloroplasts. Asexual reproduction by cell division with formation of replicate division septum. Division septum (primary wall) develops cylindrical template perpendicular to septum, which delimits semicell apex or apical processes for each daughter semicell. Secondary wall laid down on primary wall template forms folded (replicate) wall region. Parts of primary wall split or disintegrate, except on surfaces which will maintain integrity of filament. Semicell expansion causes folded secondary wall regions to straighten out to produce mature morphology. Sexual reproduction by conjugation. Filaments come together within gelatinous envelope; usually break apart before cells pair. Gametes fuse between gametangia. Mature zygospores spherical to ellipsoid, smooth-walled or with rounded warts. Desmidium cosmopolitan; several common, widespread species, usually in oligotrophic, acidic lakes and bogs.
Information contributed by: J.F. Gerrath. The most recent alteration to this page was made on 12 Sep 2013 by M.D. Guiry.
Numbers of names and species: There are 64 species names in the database at present, as well as 76 infraspecific names. Of the species names, 20 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.
Hall, J.D., Karol, K.G., McCourt, R.M. & Delwiche, C.F. (2008). Phylogeny of the conjugating green algae based on chloroplast and mitochondrial nucleotide sequence data. Journal of Phycology 44: 467-477.
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: 11 April 2002 by M.D. Guiry
Verified by: 12 September 2013 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43528
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2019. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 12 November 2019.