Euplotes daidaleos is a very common hypotrich ciliate in my sampling sites. I mostly find it among decaying leaves or in the top layer of mud. Unlike many other hypotrich ciliates, Euplotes daidaleos does not settle or only very rarely settles on the floating coverslip.

It was only in 1966 that Euplotes daidaleos was recognized and described as a distinct species by Diller and Kuonaris. This is somewhat surprising because Euplotes daidaleos is commonly found worldwide. The species mainly differs from the very similar species Euplotes patella and Euplotes aediculatus by the possession of symbiotic algae. The ciliation corresponds to that of Euplotes patella. Only the number of adoral membranelles is said to be higher in Euplotes daidaleos, which is difficult to verify in living specimens.

The specimens of my population were between 90–130 µm long. The body shape varied between broadly elliptical and almost rectangular with nearly parallel sides. I was able to clearly see the 6 frontal cirri, the two frontoventral cirri, and the buccal cirrus (s. fig. 2 a-b). At the posterior end, there are 2 left marginal cirri and on the right side two caudal cirri. The 5 transverse cirri clearly protrude beyond the posterior end and are usually somewhat spread apart (s. fig. 2 a-b). Additionally, the distal end of the transverse cirri is often frayed. The macronucleus is long and C-shaped. The small micronucleus is always found at some distance from the macronucleus (s. fig. 5). The symbiotic algae had a diameter of 5.5–6.1 µm and corresponded to the Chlorella type with its own cell nucleus (s. fig. 6).