Taxon Account

Achnanthidium trinode Ralfs in Pritchard; 1861; 872


Navicula trinodis Smith 1856
Achnanthes trinodis (W. Smith) Grunow in Van Heurck 1880

Key references


Broadly linear with inflated central section of the valve and broad subcapitate to capitate poles; in girdle view broadly rectangular with slightly reflexed poles.

Valves isopolar.

Frustules heterovalvate, raphe valve slightly concave, rapheless valve slightly convex.

Striae more or less parallel, in the valve centre slightly radiate.

Axial area
Narrow linear.

Central area
Small rounded or oval on raphe valve; on the rapheless valve larger rounded, oval or slightly lanceolate, approximately 1/2 of the valve width.

Simple straight raphe with straight proximal raphe ends, terminal raphe fissures deflected to the same side.


References are given in chronological order.

Smith W. 1856. A Synopsis of the British Diatomaceae. John van Voorst, London. 107 pp; pls 32-62, pls A-E Description
Pritchard A. 1861. A History of Infusoria including the Desmidiaceae and Diatomaceae, British and foreign. Whittaker and C., London. 968 pp; 40 Morphology; Taxonomy
Van Heurck H. 1880. Synopsis des Diatomées de Belgique. Atlas. Ducaju & Cie., Anvers.; 1-30 pls Illustrations
This page should be cited as:

Jüttner I., Carter C. F. Achnanthidium trinode Ralfs in Pritchard; 1861; 872. 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:  ].
Record last modified: 24/08/2022