Phacus ocellatus

(Pringsheim) Marin & Melkonian, 2003

Most likely ID: n.a.


Synonyms: Hyalophacus ocellata, Hyalophacus ocellatus


Sampling location: Simmelried


Phylogenetic tree: Phacus ocellatus



  • cell broadly ovoid with a ridge on the convex side
  • length 21–35 µm, width 15–25 µm
  • pellicular striation distinct
  • one eyespot at apical end
  • flagellum about body length
  • posterior spine short and bent
  • paramylon bodies numerous, often two large circular grains
Phacus ocellatus

I find Phacus ocellatus rarely, but regularly in the Simmelried between decomposing plant masses. The species is easily recognized as a member of the genus Phacus by its characteristic shape, even if no chloroplasts are present. I do not find the drawings by Pringsheim (see above) to be particularly informative. I have not found a drawing of a lateral view, with the spine bent to one side of the body at all. In my population all specimens had an eyespot. However, specimens without an eyespot have also been found.


Fig. 1 a-b: Phacus ocellatus. L = 28 µm. Two focal planes on the circular paramylon bodies (a, PA) and the striation of the pellicle (b). ES = eye spot, F = flagellum. Obj. 100 X.


Fig. 2 a-b: Phacus ocellatus. L = 29 µm. Frontal view (a) and lateral view (b) of a second specimen in brightfield illumination. Note the bent spine (arrow). Obj. 100 X.