Chroococcus subnudus

(Hansgirg) Cronberg & Komárek 1994

Most likely ID: n.a.

 

Synonym: Chroococcus turgidus var. subnudus

 

Sampling location: Sima Moor (Austria)

 

Phylogenetic tree: Chroococcus subnudus

 

Diagnosis: 

  • colonies usually 2–4 celled
  • cells round to oval, hemispherical after division
  • cells 17–25 µm in diameter
  • granules in cytoplasm present
  • intensely blue green or blackish in colour
  • sheath unlamellate or rarely lamellate, sometimes diffluent at the margins
Chroococcus-subnudus
Chroococcus subnudus

So far I have only found Chroococcus subnudus in the Sima Moor (Austria), where this cyanobacterium is very common. The cells are smaller than 25 µm (without envelope) and thus less than half the size of those of Chroococcus giganteus. In addition, the sheath of Chroococcus subnudus is homogeneous and not layered. The color can vary greatly. My population appeared green in brightfield illumination (s. fig. 1) and rather olive green in DIC (s. fig. 2).

Chroococcus-subnudus

Fig. 1: Chroococcus subnudus. D = 14–21 µm (without sheat). A group of specimens in brightfield illumination. Obj. 100 X.

Chroococcus-turgidus

Fig. 2: Chroococcus subnudus. D = 14–21 µm (without sheat). The same specimens as shown in fig. 1 in DIC. Note the homogenous, not layered sheat of the cells (HS). Obj. 100 X.

Chroococcus-subnudus

Fig. 3: Chroococcus subnudus. D = 14–21 µm (without sheat). The same specimens as shown in fig. 2 with focal plane on the cell surfaces. Obj. 100 X.