Taxon Account

Fragilaria Lyngbye, H.C.; 1819; 182

Key references


Valves linear to linear-lanceolate in valve view with rounded, (sub-)rostrate or capitate ends, frustules rectangular or lanceolate in girdle view. Sometimes a slight swelling or indentation at centre of valve.

Often cells joined at valve face to form ribbon-like colonies. Those taxa that are swollen at the centre are linked only there; otherwise linkage occurs across the entire length of the cell. The valve face is sometimes bordered by row of short spines that can extend around the poles.

More or less parallel, uniseriate striae, extending onto the mantle. Areolae simple with delicate, often disc-like cribra.

Small apical pore fields present; a single rimoportula present at one end of the valve.

Sternum generally present, linear or lanceolate. Central area variable, but often reaches to edge of the valve on one or both sides.


References are given in chronological order.

Lyngbye, H.C. 1819. Tentamen Hydrophytologiae Danicae Continens omnia Hydrophyta Cryptogama Daniae, Holsatiae, Faeroae, Islandiae, Groenlandiae hucusque cognita, Systematice Disposita, Descripta et iconibus illustrata, Adjectis Simul Speciebus Norvegicis. Hafniae. 248 pp., 70 pls. Morphology; Taxonomy; Description
Williams, D.M. and Round, F.E. 1987. Revision of the genus Fragilaria Diatom Research, Vol: 2, Issue: 2, 267-288. Morphology; Taxonomy

Similar Species

This page should be cited as:

Mann D. G., Kelly M., Jüttner I. Fragilaria Lyngbye, H.C.; 1819; 182. In: Jüttner I., Bennion H., Carter C., Cox E.J., Ector L., Flower R., Jones V., Kelly M.G., Mann D.G., Sayer C., Turner J. A., Williams D.M.. Freshwater Diatom Flora of Britain and Ireland. Amgueddfa Cymru - National Museum Wales. Available online at [Accessed:  ].

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Record last modified: 12/12/2018