Pseudohaplocaulus infravacuolatus is enormously common in Lake Constance and can be found in the plankton throughout the year. However, I have never found this peritriche ciliate in other localities. One finds the pseudocolonies exclusively on floating coenobia of the cyanobacterium Anabaena (likely Anabaena flos-aquae) on which the specimens have settled. Some Anabaena coenobia  carry up to 50 specimens. The cells in the population from Lake Constance were on average 50–60 µm in size. However, some cells reached a length of 70 µm. The species can be identified partly by its planktonic life on Anabaena spec. but also by the irregularly sized blister-shaped pellicular tubercles with which the pellicle is covered (s. fig. 7 a-d and fig. 8). Also the two contractile vacuoles are characteristic and that the stalk does not (as in Vorticella) contract in spirals, but is S-shaped.