Phacus lismorensis (Playfair, 1921)

Most likely ID: n.a.


Synonym: Phacus Rostafinskii, Phacus longicauda var. ovalis


Sampling location: Simmelried, Ulmisried


Phylogenetic tree: Phacus lismorensis



  • cell 85 – 130 µm long, about 30 µm broad
  • longitudinally obvoid in outline, slightly asymmetric
  • anterior “lips” overlapping
  • narrowing abruptly in a long spine, spine often bent
  • pellicle longitudinally striated
  • red eyespot prominent
  • chloroplast disc shaped
  • paramylon in small discs or 1-2  large discs
  • flagellum shorter than cell
  • pyrenoids absent
Phacus lismorensis

I found the first specimens of Phacus lismorensis in 1994 in Simmelried and later also in Ulmisried. In both locations the species is very common. The cells are typically asymmetrically shaped with a rapidly tapering spine. The cells can appear very curved and bent (s. Fig. 3). The shape of the paramylon grains did not seem constant to me. I found specimens its with larger, disc-shaped paramylon as well as those in which it was present in many small discs.


Fig. 1 a-c: Phacus lismorensis. L = 105 µm. a) a strongly squashed specimen, Obj. 20 X. b) the longitudinal striation of the pellicle, Obj. 100 X. c) The paramylon discs in the squashed specimen, Obj. 100 X.



Fig. 2 a-d: Phacus lismorensis. L = 128 µm. A slightly squashed specimen. Chl = disc shaped chloroplasts, ES = eye spot, NU = nucleus, PA = disc shaped paramylon granules. Obj. 100 X.


Fig. 3 a-c: Phacus lismorensis. L = 105 µm. a, b) a strongly bent specimen. c) the same specimen strongly squashed. Obj. 100 X.

In many samples I found infestation of Phacus lismorensis by a parasitic fungus. In most cases it was only one very large parasitic cell, which was intracellular (s. Fig. 4). Sometimes there were even two parasitic cells. Reddish-brown metabolites were deposited in these cells and after prolonged infestation, the paramylon granules were completely degraded to feed the parasite. Unfortunately, I could not observe the complete life cycle of the parasitic fungus.


Fig. 1 a-c: Phacus lismorensis. L = 88 µm. A specimen that has been attacked by a parasitic fungus. PC = parasitic cell, NuP = nucleus of the parasitic cell. Obj. 100 X.