Ditylum J.W.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.

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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 2015-09-29 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

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.

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).

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Contributors
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.

Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=44389

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 29 September 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 26 February 2024

 
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