So far I have only found a single specimen of Ctedoctema ovalis in the Simmelried in November 2021. However, it is possible that I have overlooked other specimens so far. At least the species seems to be rare.

Kahl (1926) also found only a few specimens of Ctedoctema ovalis. In his short description he speculates that it may also have been Cyclidium centrale. However, this species is said to be more slender in shape and Kahl also drew Cyclidium centrale more slender. With a length of 43 µm, my specimen of Ctedoctema ovalis was somewhat larger than Kahl indicated (35 µm), but the oval shape corresponds exactly with his drawing (s. drawing above). I therefore believe that Ctedoctema ovalis is present here, even if I cannot rule out the possibility that this species is synonymous with Cyclidium centrale.

Kahl was unable to recognize a frontal plate in his specimens. It is in fact very inconspicuous and can only be seen in one of the photos I made (s. fig. 1 d). I was able to recognize the undulating membrane of the peristome (s. fig. 1 a), but only in the attached state, so that I could not check whether it rises towards the posterior end, as described by Kahl. The macronucleus lies in the anterior third and, according to my observations, is surrounded by several adjacent micronuclei (s. fig. 1 e). The fringe of extrusomes under the pellicle is concise and easy to recognize. These are short rods with a length of about 1.5 µm. In the resting state the cilia are spread out and slightly bent forward (s. fig. 1 f), as is also the case with the related species Ctedoctema acanthocrypta.