Ditylum Bailey ex L.W.Bailey, 1861
Lectotype species: Ditylum trigonum L.W.Bailey ex L.W.Bailey
Currently accepted name for the type species: Ditylum brightwellii (T.West) Grunow
Original publication:Bailey, L.W. (1861). New species of microscopical organisms, chiefly from the River Para . Proceedings of the Boston Society of Natural History 8: 162-169.
Type designated in Boyer, C.S. (1927). Synopsis of North American Diatomaceae. Part I - Coscinodiscatae, Rhizosolenatae, Biddulphiatae, Fragilariatae. Proceedings of the Academy of Natural Sciences of Philadelphia 78(Suppl.): 1-228.
Taxonomic status: currently recognized as a distinct genus.
Most recent taxonomic treatment adopted: Round, F.E., Crawford, R.M. & Mann, D.G. (1990). The diatoms Biology and morphology of the genera. pp. [i-ix], 1-747. Cambridge: Cambridge University Press.
Description: Cells free-living in the marine plankton, usually lying in girdle view, which is rectangular with a very conspicuous 'spine' arising from the centre of each valve. In valve view the cell is usually triangular in outline, but some populations of bipolar or quadripolar forms have been encountered. Numerous discoid chromatophores occur around the periphery. Rarely forming large populations but frequently found, especially in neritic plankton. Easily cultured and therefore used in several notable experimental studies. Valves bi-, tri-, or quadrangular, with a conspicuous central tube arising from a small, clear central area. Rows of simple elliptical or round areolae occluded by rotae radiate from the central region to the valve mantle edge but are broken by a ridge bearing flattened spines, which often appear as two 'gutter' pieces fusing at the apex where further small spinules occur. In some forms the ridge is well-developed and deep but is perforated by slits, as though the spines had fused. In our material of a bipolar form the fimbriate ridge is circular rather than triangular. The region outside the ridge is valve mantle and here the rotae are attached at only two points, whereas on the valve face they are more complex. isolated simple pores occur scattered over both valve face and mantle; these probably lack vela. Internally a single rimoportula opens at the base of the central external tube and is unusual in having a closed central portion. Copulae numerous, scale-like, with ligulae on some. Scanning electron micrographs often show longitudidnal ridges and furrows but we have not investigated these. Resting spores have been reported.The most recent alteration to this page was made on 29 Sep 2015 by M.D. Guiry.
Comments: This genus was confused with the closely related Lithodesmium by earlier workers (see Hustedt, 1927-1966). A small genus of which only D. brightwelli and D. sol are regularly recorded. There are forms or life cycle stages of this genus which require further investigation. A recent study has been made of valve formation (Li & Volcani, 1985a).
Numbers of names and species: There are 13 species names in the database at present, as well as 2 infraspecific names. Of the species names, 4 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: 29 September 2015 by M.D. Guiry
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=44389
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 23 January 2019.