Closterium Nitzsch ex, 1848
Lectotype species: Closterium lunula Ehrenberg & Hemprich 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 Silva, P.C. (1952). A review of nomenclatural conservation in the algae from the point of view of the type method. University of California Publications in Botany 25: 241-323.
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: Cell solitary (rarely aggregated), small to large (72-1700 um), usually elongate-cylindric to elongate-fusiform, straight or, more commonly, curved (at least at ends). Cells usually tapering toward both ends; ends acute, rounded or truncate. Cell wall smooth or with longitudinal striae or costae, wall colorless, yellowish or brown (sometimes only at ends of cell). Cell wall ultrastructurally with outer, electron-dense amorphous layer and inner microfibrillar layer. Perforations in outer layer associated with less dense fibrillar areas in inner layer, but continuous pores similar to those in Desmidiaceae not present. Girdle bands (extra wall sections) present in some species. Chloroplasts two (rarely four) per cell, axial, elongate, stellate in end view, with one to many, axial or scattered pyrenoids. Pyrenoids usually numerous, except in very small species, and in axial row or scattered throughout chloroplast. Nucleus at middle between chloroplasts. Each end of cell with vacuole containing one or more granules of calcium sulfate. Asexual reproduction by transverse cell division. Daughter cell morphogenesis involves formation new semicells by gradual expansion from severed end, and in one species group, also involves formation of extra pieces of wall (girdle bands). Aplanospores and parthenospores observed in some species. Sexual reproduction by homothallic or heterothallic conjugation. Gametangia come together in mucilaginous envelope. Gametangia often immature sister cells from recent division. Both cells split at median suture; gametes partially or completely move out to fuse between gametangia. Zygospores spherical, ellipsoid, quadrate or irregular; some with scattered, broad conical protuberances or with long lobes surrounded by empty gametangial wall pieces. Zygospore wall smooth, with pits, scrobiculations, ridges or spines. Karyogamy during germination, followed by meiosis.
Information contributed by: J.F. Gerrath. The most recent alteration to this page was made on 12 Sep 2013 by M.D. Guiry.
Comments: Closterium is cosmopolitan, in periphyton of acidic, oligotrophic lakes and ponds; rarely in in more alkaline, eutrophic environments. Some species (e.g. C. aciculare) planktonic. Experimental studies on host range of parasitic phycomycetes may help in delimiting certain species groups. Several reproductively isolated mating groups (biological species) known in two morphological species complexes (in C. ehrengergii these are polyploids).
Numbers of names and species: There are 419 species names in the database at present, as well as 945 infraspecific names. Of the species names, 206 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: 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=43525
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 16 October 2018.