Taxon Account

Fragilariforma D.M.Williams & Round; 1988; 265

Key references

Williams D.M., Round F.E. 1987. Revision of the genus Fragilaria. Diatom Research. 2(2): 267-288.


Frustules rectangular in girdle view forming linear, ribbon-like colonies. Valves linear, lanceolate or elliptical with rostrate to capitate ends.

The sternum is narrow or absent.

Striae uniseriate and extending onto the mantle, areolae occluded by simple vela.

Apical pore fields are present.

A single rimoportula is present near one valve end.

Spines on the valve margins are either simple projections or complex with large interdigitating, spatulate tips.

The cingulum consists of 4-6 open, ligulate copulae, each with a single row of poroids.

Multiple disc-shaped plastids are present.


References are given in chronological order.

Williams D.M., Round F.E. 1987. Revision of the genus Fragilaria. Diatom Research. 2(2): 267-288. Illustrations; Taxonomy;
Williams D.M., Round F.E. 1988. Fragilariaforma, nom. nov., a new generic name for Neofragilaria Williams & Round. Diatom Research. 3(2): 265-267. Morphology; Taxonomy
Williams D.M. 1990. Cladistic analysis of some freshwater araphid diatoms (Bacillariophyta) with particular reference to Diatoma and Meridion. Plant Systematics and Evolution. 171: 89-97. Taxonomy
Kilroy C., Sabbe K., Bergey E.A., Vyerman W., Lowe R. 2003. New species of Fragilariforma (Bacillariophyceae) from New Zealand and Australia. New Zealand Journal of Botany. 41(3): 535-554. Morphology; Taxonomy; Illustrations
Metzeltin D., Lange-Bertalot H. 2007. Tropical diatoms of South America II. Special remarks on biogeography disjunction. Iconographia Diatomologica, Vol. 18., Annotated Diatom Micrographs. Diversity-Taxonomy-Biogeography. H. Lange-Bertalot (ed.), A.R.G. Gantner Verlag K.G. 877 pp Morphology; Illustrations
This page should be cited as:

Williams D. M. Fragilariforma D.M.Williams & Round; 1988; 265. 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: 27/12/2020