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
Reavie E.D., Kireta A.R. 2015. Centric, Araphid and Eunotioid Diatoms of the Coastal Laurentian Great Lakes. 62. Bibliotheca Diatomologica. 184 pp Morphology; Ecology; Illustrations
Heudre D., Wetzel C.E., Moreau L., Van de Vijver B., Ector L. 2019. On the identity of the rare Fragilaria subconstricta (Fragilariaceae), with Fragilaria species forming ribbon-like colonies shortly reconsidered. Plant Ecology and Evolution. 152(2): 327-339. Morphology; Illustrations; Taxonomy
Kahlert M., Kelly M.G., Mann D.G., Rimet F., Sato S., Bouchez A., Keck F. 2019. Connecting the morphological and molecular species concepts to facilitate species identification with the genus Fragilaria (Bacillariophyta). Journal of Phycology. 55(4): 948-970. Morphology; Biology; Illustrations
Van de Vijver B., Wetzel C.E., Kusber W.-H., Ector L. 2020. Observations on and typification of Synedra crotonensis f. belgica Grunow and Fragilaria crotonensis var. prolongata Grunow (Fragilariaceae, Bacillariophyta) and the introduction of Fragilaria prolongata comb. et stat. nov. Notulae Algarum. 166: 1-6. Morphology; Taxonomy; Illustrations

Similar Species

This page should be cited as:

Mann D. G., Kelly M., Jüttner I. Fragilaria Lyngbye, H.C.; 1819; 182. In: Jüttner I., Carter C., Chudaev D., Cox E.J., Ector L., Jones V., Kelly M.G., Kennedy B., Mann D.G., Turner J. A., Van de Vijver B., Wetzel C.E., 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: 27/12/2020