155,256 species and infraspecific names are in the database, 21,864 images, 60,045 bibliographic items, 435,064 distributional records.

Coscinodiscus Ehrenberg, 1839, nom. et typ. cons.

Lectotype species: Coscinodiscus argus Ehrenberg

Original publication and holotype designation: Ehrenberg, C.G. (1839). Über die Bildung der Kreidefelsen und des Kreidemergels durch unsichtbare Organismen. Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin 1838: 59-147, pls I-IV, tables 1, 2.
 Download PDF

Taxonomic status: currently recognized as a distinct genus.

Most recent taxonomic treatment adopted: Tomas, C.R., Eds (1996). Identifying marine diatoms and dinoflagellates. pp. 1-858. San Diego: Academic Press Inc.

Nomenclatural notes
According to CAS "Name conserved with a conserved type (see ICBN 1994, p. 120, ref. 006916). Five species of Coscinodiscus in original publication, C. argus, C. centralis, C. lineatus, C. minor, C. patina, no type designated. The type designated by Boyer, 1927 (ref. 000155) p. 41, C. radiatus Ehr., is untenable because it is not one of the original species. Pre-conservation lectotypification with C. argus in Ross & Sims 1974, p. 103 (ref. 005306). Fryxell 1978 (ref. 004158) proposed to conserve Coscinodiscus with a conserved type." - (20 Oct 2011) - M.D. Guiry

This is a genus of fossil species, or a genus with a fossil type species, or a genus the type species of which was originally described as a fossil.

Description: Cells discoid, sometimes thin (like a coin) or more barrel-shaped, occasionally with valve mantle deeper on one side. Plastids numerous, discoid. Free-living, marine and often abundant in the phytoplankton. A few species reported from lakes but usually only in high conductivity waters and many records need checking. Widely distributed in the fossil record. Valves saucer-to petri-dish shaped. Valve face flat, sometimes depressed centrally; areolae radiating from central annulus, sometimes sectored. Ovoid and triangular forms occur as fossils. Valves loculate with complex external vela with central small pores and an external ring of larger openings. Vela often becoming diamond-shaped on valve mantle. The internal openings are foramina, often rimmed and becoming smaller on the valve mantle. Rimoportulae present at intervals around the valve; external openings simple; internally with small cup-shaped expansions. Macro-rimoportulae sometimes occur at intervals in the ring; these aree larger, sometimes with flat apical expansions and curled; the macro-rimoportulae open via larger external apertures. Copulae poroidal, split and ligulate.

The most recent alteration to this page was made on 19 Oct 2015 by M.D. Guiry.

Comments: This genus is also classified occasionally as being a member of the Bacillariophyta, Bacillariophyceae. See ING entry. This is a large genus and requires extensive study since there is much variation at the ultrastructural level. Fryxell (1978) has documented the typification. Several species have been removed to Thalassiosira, others to Actinocyclus - many of the changes involve species living in tropical lakes. C. nitidus has been transferred to Psammodiscus by Round & Mann (1980). Many small centric forms need checking and the position of the vela determined; any forms found to have fultoportulae are almost certainly Thalassiosira species. Sims (1989) has reviewed three subgroups of Coscinodiscus and discussed their stratigraphical distribution and phylogeny.

Numbers of names and species: There are 754 species names in the database at present, as well as 387 infraspecific names. Of the species names, 164 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.

Hustedt, F. (1930). Bacillariophyta (Diatomeae) Zweite Auflage. In: Die Süsswasser-Flora Mitteleuropas. Heft 10. (Pascher, A. Eds), pp. [i]-vii, [1]-466. Jena: Verlag von Gustav Fischer.

Scott, F.J. & Thomas, D.P. (2005). Diatoms. In: Antarctic marine protists. (Scott, F.J. & Marchant, H.J. Eds), pp. 13-201. Canberra & Hobart: Australian Biological Resources Study; Australian Antarctic Division.

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: 19 October 2015 by M.D. Guiry

Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43692

Citing AlgaeBase
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 22 May 2019.

SITE © 1996 - 2019 M.D. Guiry. All rights reserved.

Website Design : 249 Design Studio