Closterium lunula

Closterium lunula is a well defined species. The large, thick-set, slightly curved cells are gradually attenuated from the middle towards the poles. Apices are rounded truncate and a little bit recurved. The cell wall is smooth (not striate) and the chloroplasts contain many scattered pyrenoids.  Closterium lunula is characteristic of slightly acidic, mesotrophic habitats. Because of the big cells (high sinking rate) it is only to be expected in benthos and tychoplankton of shallow water bodies. In the Netherlands it is a rather common species, particularly in fen hollows.

Image © Henk Schulp

Closterium lunula. Note the spherical, terminal vacuole at the slightly recurved cell apices

Cell dimensions (L x B): ca 560 x 90 µm

<< Image on the left:

Another cell of Closterium lunula, next to a cell of Netrium digitus to illustrate the large cell dimensions.

Image © Henk Schulp

A series of Closterium lunula cells photographed in dark field. Terminal vacuoles stand out as white globules.

Image © Wim van Egmond