Chroococcus minutus

(Kützing) Nägeli, 1849

Most likely ID: n.a.


Synonym: Protococcus minutus


Sampling location: Sima Moor (Tirol, Austria), Simmelried


Phylogenetic tree: Chroococcus minutus



  • colonies small, usually 2–8 cells, occasionally cells solitary
  • solitary cells spherical, after cell division semispherical
  • with colorless, homogeneous sheath, without distinct layers
  • cells without sheath 4–12 µm
  • color blueish-green or olive green
Chroococcus minutus

I have found Chroococcus minutus so far in Simmelried as well as in Sima Moor (Tyrol, Austria). This cyanophyte can be identified by the fact that the surrounding gelatinous sheath shows no clear layers and appears homogeneous. The cells have mostly a diameter of 10 µm and are mostly present in colonies of 2–4 cells. I could not detect colonies with 8 cells. Single cells are spherical and cells after cell division are semispherical.


Fig. 1: Chroococcus minutus. An aggregation of colonies from the Sima Moor (Austria) found in July 2017. Obj. 100 X.


Fig. 2: Chroococcus minutus. A squashed aggregation of colonies and solitary cells found in the Simmelried in November 2005. Note the spherically shaped solitary cells (arrows). Obj. 40 X.


Fig. 3: Chroococcus minutus. L = 10 – 12 µm. A squashed aggregation of colonies. Note the homogeneous sheath without visible layers. Obj. 100 X.