So far I have found Microthorax bidentatus exclusively in the Simmelried. However, I have found only a few specimen over the years. The last time I found the species in November 2019 and in December 2022. I may have missed it earlier, as the two characteristic teeth at the posterior end are only visible at higher magnifications. In the literature I have found only the very short description by Kahl, who also gives only a single drawing from the right side (s. drawing above). The individuals in my population differ partly from the description of Kahl. He gives a size of 16 µm, while my individuals were 28 – 31 µm long. The ciliation of the right side Kahl only drew without giving any further description on it. On his drawing one can recognize a continuous dorsal row of cilia, which runs parallel to the dorsal margin. He also draws two other short rows, approximately in the middle of the cell. According to my observations, the dorsal row is interrupted in the middle and the two rows beginning approximately in the middle of the cell find a continuation in the posterior third after an interruption (s. fig. 2 a-b).