I regularly find Notosolenus mediocanellatus in the uppermost mud layer in the Simmelried. I have not yet been able to find this species in my other sampling sites.

Notosolenus mediocanellatus was originally described as Petalomonas mediocanellata by Stein (1878). He overlooked the trailing flagellum in the ventral groove and therefore placed it in the genus Petalomonas. Later authors (e.g. Lemmermann, 1913) also overlooked the trailing flagellum. Only Schroeckh et al. (2002) were able to identify the trailing flagellum, which is difficult to recognize in the ventral groove. Accordingly, Schroeckh et al. placed the species into the genus Notosolenus and named it Notosolenus mediocanellatus.

I was also able to detect the trailing flagellum in my population (s. figs. 1 b and 2 c). According to my observations, it is also longer than a fourth of the body length, as described by Schroeckh et al. In fact, the trailing flagellum is very hard to recognize because the ventral groove, in which the trailing flagellum lies, narrows towards the anterior end. As a result, the flagellum is obscured by the overlapping edges of the groove. In my population, the specimens were between 15–22 µm long. I could not detect a dorsal groove, as described by Stein. Thus my observations agree with those of Schroeckh et al.