Desmid of the month - February 2006

Desmid of the month
February 2006

Mesotaenium macrococcum

Cells of Mesotaenium macrococcum are short-cylindric with broadly rounded angles. Contrary to the previously represented species, M. endlicherianum and M. caldariorum, cells of M. macrococcum use to occur in dense, monospecific populations embedded in a common mucilaginous mass. The species under discussion is locally common on wet, nutrient-poor, sandy or loamy soil and may cover the substrate over a relatively large surface (many square decimeters).

Image © Henk Schulp

Colony of Mesotaenium macrococcum. The cylindric cells are provided with a plate-like chloroplast. In part of the cells the chloroplast is observed in frontal view (almost contacting the cell wall), in another part of the cells the chloroplast is met with in lateral view (filling in only a small portion of the cell content).

Cell dimensions (L x B): 20-25 x 15 µm

<< Image on the left:

Dense, monospecific populations use to attract predators. In this picture it is the amoeba Vampyrella that attacks a Mesotaenium cell.

Image © Henk Schulp

Image on the right:

After having digested the content of some two adjacent Mesotaenium cells, a Vampyrella cell has transformed into a cystoid resting-stage. Notice the circular opening by way of which Vampyrella penetrated into the Mesotaenium cells.

<< Image on the left:

Vampyrella looking for another victim.