(®gures 1h, 2m)
Description. Cell outline usually elliptical, 4±7 Mm long, 2±4 Mm wide. With two unequal ¯agella emerging from a subapical pocket. Cells are ¯exible. The anterior ¯agellum is about the length of the cell or slightly shorter and curves back over the rostrum. The anterior ¯agellum wraps around the anterior part of the cell and the mouth is pressed against food particles when the cell is feeding. The acronematic posterior ¯agellum is about 2±4 times the length of the cell and has a sinuous pro®le in swimming cells. Cells rotate around their longitudinal axes when swimming. The nucleus is located near the middle of the cell. Common.
Remarks. Cell length was previously reported to be from 7 to 15 Mm. This species has been reported from marine sites in Antarctica, North Atlantic, subtropical and tropical Australia, Brazil, Denmark, Fiji, Gulf of Finland, Greenland, Hawaii, and Panama (Larsen and Patterson, 1990; Vùrs, 1992a, 1992b, 1993a; Patterson et al., 1993; Ekebom et al., 1996; Patterson and Simpson, 1996; Tong, 1997a; Tong et al., 1997, 1998). Generally, our observations are consistent with those of previous authors. Bodo designis has also been found in several freshwater sites. It appears to be cosmopolitan. Sometimes, this species occurs in large numbers. It has been characterized by the rotating behaviour of swimming cells, but B. cygnus reported by Patterson and Simpson (1996) and B. platyrhynchu s also have a rotating swimming movement. Bodo designis sometimes co-occurs with B. cygnus, but B. cygnus can be distinguished because it has a spiral groove.