Navicula Bory, 1822
Holotype species: Navicula tripunctata (O.F.Müller) Bory
Publication details: Bory, 1822: 128
Original publication and holotype designation: B[ory de Saint-Vincent, J.B.G.M.] (1822). Bacillariées. Dictionnaire Classique d'Histoire naturelle 2: 127-129.
Request PDFPrecise date of publication: 31 Dec 1822
Description: Valve outline variable, usually more or less lanceolate with acute to rounded, sometimes capitate apices. The striae may be parallel or radiate at the centre, tending to become convergent near the apices, with a single row of pores around the apex. The striae are composed of loculate areolae (loculi) which have an inner rica and an external linear foramen, elongated perpendicular to the path of the stria. The loculi are usually elliptical and their depth is less than their breadth. The interstriae are thicker than the loculi are deep. The loculi around the apex have their long axes perpendicular to the valve margin, and may impinge on the striae proper and have V-shaped foramina. The raphe slit lies in an internally thickened region (raphe costa) with the internal fissure deflected to one side of the crest of this costa, except near the centre and the poles. At the poles the internal raphe fissures end in slightly twisted helictoglossae, and at the centre in a slightly expanded central nodule, which is a continuation of the raphe costa. There is additional longitudinal thickening (a definite rib in some species) to one side of the raphe, distal to the internal fissure. Externally the raphe fissures are more or less straight for most of their length, slightly expanded at their central endings and strongly hooked near the valve apex, always to the same side in each valve. The girdle region is narrow, made up of two girdle bands per frustule, without any pores or other markings. In the living cell there are two rectangular, plate-like chloroplasts which lie along the girdle region, on either side of the conspicuous central cytoplasm, in which the nucleus lies. The plastids have smooth margins and do not extend onto the valve faces. There are often two clear droplets, one between each pole and the central cytoplasm.
Information contributed by: Cox (1979: 149, "Navicula subg. Navicula emend. E.J. Cox"). The most recent alteration to this page was made on 2025-04-30 by M.D. Guiry.
Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Cox, E.J. (1979). Taxonomic studies on the diatom genus Navicula Bory: the typification of the genus. Bacillaria 2: 137–153, 6 figures, 3 plates.
Comments: Motile, benthic species found in marine, brackish and freshwater habitats. The majority occur as free-living individuals but a few species produce and live within mucilage tubes.
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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=43698
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 30 April 2025. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 09 May 2025
