Holotype species: Cymatosira lorenziana Grunow
Original publication and holotype designation: Grunow, A. (1862). Die Österreichischen Diatomaceen nebst Anschluss einiger neuen Arten von andern Lokalitäten und einer kritischen Uebersicht der bisher bekannten Gattungen und Arten. Verhandlungen der kaiserlich-königlichen zoologisch-botanischen Gesellschaft in Wien 12: 315-472 [Abt 1], 545-588 [Abt. 2], 7 pls.
Taxonomic status: currently recognized as a distinct genus.
Most recent taxonomic treatment adopted: Hasle, G.R. & Syvertsen, E.E. (1996). Marine diatoms. In: Identifying Marine Phytoplankton. (Tomas, C.R. Eds), pp. 5-385. San Diego: Academic Press.
Description: A small genus of marine benthic diatoms forming filamentous colonies of rectangular cells, the sides of which are curved so that the apices do not touch. Cells united by central interlocking spines which prevent separation of the cells. Plastids 1 (2, 4) plate-like, lying at either end of the cell but details are not clear. Although often collected in inshore plankton it probably grows in the epipsammon; certainly it also occurs on sandy beaches and salt marshes. Frustules heterovalvar. Valves broadly to narrowly lanceolate with pointed or blunt apices which terminate in ocelluli; these are angled somewhat to the valve face and surrounded by a distinct rim. Hasle, von Stosch & Syvertsen (1983) report small ocelluli, except on the end (separation) valves of colonies where the ocellulus is larger on one valve. Areolae poroidal, arranged in lines across the valves. Sternum absent; in some there is a clear central region but when viewed from the inside (the best view to confirm a sternum) this is not thickened or distinct in any way and so does not appear to be a true sternum. Areolae occluded by cribra, which protrude from the outer valve surface and have external spinules. Marginal spines conspicuous, T-shaped, the upper parts of the Ts sometimes fused; with fine filigree (not illustrated, since it has been removed by our cleaning process) betweden the stems of the adjacent T-pieces. Complex spines forming a 'fence-like' structure are reported by Fryxell & Miller (1978). In C. belgica the T-shaped spines in the central interlocking region are larger than the remainder. Rimoportulae on one valve only, where there is one, placed off-centre, just internal to the row of spines along one edge or nearer the centre; internally the rimoportula is sessile. Copulae simple, open, with pores. Complex ligulae occur on the copulae and fimbriae on the most abvalvar band.The most recent alteration to this page was made on 20 Oct 2011 by M.D. Guiry.
Comments: Fryxell & Miller (1978) and Hasle et al (1983) give further details. The complicating feature in this genus lies in the two types of spines plus the fact that end (separating) cells also have a somewhat different morphology resulting in four valve types differing only slightly in morphology. The genus, however, clearly belongs in the Cymatosiraceae.
Numbers of names and species: There are 25 species names in the database at present, of which 11 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: 23 April 2002 by M.D. Guiry
Verified by: 20 October 2011 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=44376
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2020. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 14 August 2020.