Catenula turgida

Catenula turgida (Zacharias, 1902) Fig. 2 A – D Sampling sites. Display case with vegetation – Tanks 2 and 3. Description. A Catenula reaching 400 μm in length. The body shape is conical, with a narrowing posterior part (Fig. 2 A). The head is clearly separated from the rest of the body, with a slight tripartition (Fig. 2 A). In our specimens, we could not observe a statocyst. At the base of the head, a ring of cilia is present (Fig. 2 D) with four furrows on the ventral side. The ciliated ring is followed by a small triangular mouth opening and a long pharynx with cilia arranged like a comb (Fig. 2 B). The gut does not reach the posterior end of the body, which is blunt, without a tail. The protonephridial canal is visible throughout the whole length of an animal and ends in the caudal region. In the epidermis, around 3 μm long rod-shaped rhabdoids occur, grouped into sets of a few (Fig. 2 C). The animal is covered by a uniform layer of cilia, with longer, stiffer ones distributed sparsely but evenly around the body (Fig. 2 B). The worms can be cultured with some difficulty on Chalkley’s Medium with wheat grain at 20 ° C. In the cultures, they swim freely in the water column or crawl in the sediment at the bottom of the dish and prey on unidentified bacteria. Distribution. Germany, Sphagnum in moorland near Plön (Zacharias 1902); Brazil, bromeliads and stream in São Paulo (Marcus 1945); Finland, raised bog in Tvärminne (Luther 1960); Sweden, Sphagnum from various locations (Larsson and Willems 2010); Brazil, wetland in Rio Grande do Sul (Braccini et al. 2017) – however, the general body shape of the last is more reminiscent of C. sawayai.