Taxon Account

Rhoicosphenia A. Grunow; 1860; 511


Gomphonema curvata Kützing

Key references

Levkov Z., Caput Mihalic K., Ector, L. 2010. A taxonomic study of Rhoicosphenia Grunow (Bacillariophyceae). Fottea. 10(2): 145-200.


Frustules curved in girdle view; valves heteropolar or isopolar, linear, linear-elliptical or lanceolate in valve view, if heteropolar then with rounded head pole and acute foot pole.

Frustules heterovalvar, one valve having a full raphe system, the other with short raphe slits at the two poles; valves heteropolar or isopolar and bilaterally symmetrical; cells usually lying in girdle view. Isolated valves lie in valve or girdle view.

Striae uniseriate (with occasional biseriate striae), parallel or slightly radial; areolae linear, with their long axes at right angles to the striae, occluded by fine pore plates (hymenes) close to their inner apertures. At the base-pole there is an area (pore field) of more densely packed pores, through which a stalk is secreted.

Axial area narrow, widening towards the centre. Central area not clearly differentiated from the axial area.

Raphe straight, with straight, expanded endings at the centre externally, hooked endings at the centre internally, and hooked terminal fissures.

Girdle composed of open bands, each with a single row of areolae.

One complex chloroplast per cell, with its centre against one side of the girdle and containing a flat pyrenoid, from which lobes extend out beneath the valves to the opposite side of the girdle, leaving the raphe more or less free.


References are given in chronological order.

Grunow A. 1860. Über neue oder ungenügend gekannte Algen. Erste Folge, Diatomeen, Familie Naviculaceen. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien. 10: 503-582; pls. 3-7. Morphology; Taxonomy; Description
Lange-Bertalot H. 1980. Ein Beitrag zur Revision der Gattungen Rhoicosphenia Grun., Gomphonema C. Ag., Gomphoneis Cl. Botaniska Notiser. 133: 585-594. Morphology; Taxonomy; Illustrations
Mann D.G. 1982. Structure, life history and systematics of Rhoicosphenia (Bacillariophyta). I. The vegetative cell of Rh. curvata. Journal of Phycology. 18(1): 162-176. Biology; Illustrations; Morphology; Taxonomy
Levkov Z., Caput Mihalic K., Ector, L. 2010. A taxonomic study of Rhoicosphenia Grunow (Bacillariophyceae). Fottea. 10(2): 145-200. Morphology; Taxonomy; Description; Illustrations;
Thomas E.W., Kociolek J.P. 2015. Taxonomy of three new Rhoicosphenia (Bacillariophyta) species from California, USA. Phytotaxa. 204(1): 1-21. Illustrations; Morphology; Taxonomy
Thomas E.W., Stepanek J.G., Kociolek J.P. 2016. Historical and current perspectives on the systematics of the 'enigmatic' diatom genus Rhoicosphenia (Bacillariophyta), with single and multi-molecular marker and morphological analyses and discussion on the monophyly of 'monoraphid' diatoms. PLOS ONE. 11 (4): e0152797. Biology
This page should be cited as:

Mann D. G. Rhoicosphenia A. Grunow; 1860; 511. In: Jüttner I., Carter C., 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