Placus luciae (Kahl, 1926)

Most likely ID: n.a.


Synonym: Thoracophrya luciae


Sampling location: Ulmisried


Phylogenetic tree: Placus luciae



  • length about 50 µm
  • body oval shaped
  • oral apperture located apically
  • lateral invgination of unknown function in anterior third
  • macronucleus oval
  • pellicle with conspicuously spiral ridges
  • contractile vacuole located ventral and subterminal
Placus luciae

Placus luciae is described as a very common ciliate. However, since 1992 I have only been able to find one specimen in Ulmisried (2022). There I found the specimen in a sample from an accumulation of leaves, which were jammed in front of a weir overflow. Placus luciae is quite small at about 50 µm, but it is immediately recognizable by fielded and ribbed stripes arranged parallel to the kineties. The purpose of this fielding is unknown. In addition, it also possesses a laterally located invagination (LI). The function of the invagination is also unknown and it is not associated with the mouth opening (MO):


Fig. 1 a-c: Placus luciae. L = 47 µm. a,b) slightly squashed specimen. c) strong squashed specimen. CV = contractile vacuole, Ma = macronucleus, LI = lateral invagination, OA = oral apparatus. Obj. 100 X.


Fig. 2 a-b: Placus luciae. L = 47 µm. The fielded and ribbed stripes of the pellicle in two focal planes. Obj. 100 X.