I have so far Salpingoeca frequentissima only recorded in the Simmelried, but the species is probably also present in my other sampling sites, as it is a very common species. Salpingoeca frequentissima is best observed when specimens settle on the floating coverslip.

The specimens I found had a length of 14–17 µm (of lorica), which is somewhat longer than stated by Huber-Pestalozzi (1941). However, the shape of the shell corresponds exactly to his description. The hollow stalk of the case is not filled by the cell. The opening of the lorica is widened like a funnel, with the upper edge of the lorica being wider than the center (s. fig. 1 a). The nucleus is located in the upper third with a distinct, spherical nucleolus. The flagellum is surrounded at its base by a ring of fine microvilli, which form a collar. The collar was 8–10 µm high in my specimens (s. fig. 2 a-b).

Salpingoeca frequentissima can be distinguished from the similar species Salingoeca amphoridium and Salpingoeca convallaria by the shape of the lorica. Salpingoeca amphoridium has no stalk and the body is piston-shaped. In contrast, Salpingoeca convallaria has a distinct, thread-like stalk and the opening of the lorica is narrower than the center.