Cosmarium pseudoprotuberans
Image © Jos Gysels


Cosmarium pseudoprotuberans. Notice widely opening sinus and semicells that are about hexagonal in outline.
Cell dimensions ( L x B): ca 38 x 36 µm



Cosmarium pseudoprotuberans
Image © Iryna Shyndanovina (after Ukrainian material)

C. pseudoprotuberans var. sulcatum in frontal and in apical view, respectively. Notice undulate margin in apical view indicating longitudinal plications of the cell wall.




 


Desmid of the Month
January 2025

Cosmarium pseudoprotuberans


C. pseudoprotuberans is a smooth-walled Cosmarium characterized by a widely opening cell sinus separating semicells that are about hexagonal in outline with broadly rounded angles. Semicell wall of its var. sulcatum (distinguished a separate species as well) in its centre is marked by a number of longitudinal plications. In the Netherlands, C. pseudoprotuberans is a rather rare species, particularly known from moorland pools in the southern part of the country.


Cosmarium pseudoprotuberans
Image © Robin Matthews (after North American material)

SEM picture of C. pseudoprotuberans.

Cosmarium pseudoprotuberans
Image © Robin Matthews (after North American material)

SEM picture of C. pseudoprotuberans var. sulcatum. Notice lonigitudinal plications in the central part of the semicell wall (with an extra bulge in the middle).

Cosmarium pseudoprotuberans
Image © Iryna Shyndanovina (after Ukrainian material)

Preserved cell of C. pseudoprotuberans var. sulcatum in frontal, lateral and apical view, respectively. Notice, in lateral view, a small marginal bulge in the median part of the semicell indicating a separate tuber.