Darbyshirella species

I found this Darbyshirella species in a sample from a freshwater aquarium. This sample was send to me by Wolfgang Bettighofer. I kept some wet preparations in my humidity chamber. After about ten weeks I found several specimens of this Darbishirella species attached to the cover glass, while some cells could be observed inside filamentous blue algae. Obviously these cells were consuming the content of the algae. In and outside these algae a number of double walled cysts were observed. These cysts were mostly circular or elongated, sometimes irregular in outline.

This reticulum is more than 1 mm large. A part of the cell is present inside the filament of the alga in the central part of the image.
The same reticulum one day later. It has expanded to the left. Notice its position relative to the algal filament.
About 15 nuclei are visible.
This is a flattened multinucleated cell. At the top two strings of a reticulum are visible. Probably the diatoms have been captured by the cell.
One day later the cell has broken up into several smaller cells.
Darbyshirella inside a filament of a blue algal. The reddish brown spots are digested algae.
Darbyshirella feeding on a filamentous blue alga. a – green food particles inside Darbyshirella; b – cell attacked by Darbyshirella; notice the bright color; c – untouched algal cell.
Seven cysts, three inside a filament.
Left: two “knobs” of a Darbyshirella reticulum separate themselves from the main mass.   Right: one day later the “knobs” have encysted and the reticulum has gone.
Cysts with different shapes.
Cysts inside a blue algal filament.
Broad flattened cell
The same cell as above, Phase Contrast, with many nuclei, one nucleus arrowed
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