Description: The cells are (9)–10–14–(16) times longer than they are wide, evenly curved, and continuously narrow towards the slightly truncated cell ends, in which a small button-like thickening (end pore) is usually also visible. The cell wall is smooth, and there are no girdle bands. Distinguished from similarly curved closteria by its extremely slender shape.

Dimension: Length (160)–180–300–(380) µm, width (15)–20–30–(40) µm.

Occurrence:  Commonly found in weakly to moderately acidic small water bodies of transitional mires and the like.

Note: The image on the right shows the strongly curved variety arcuatum.

Copyright by Prof. Rupert Lenzenweger, Ried im Innkreis, Austria.