Body elongate obconical, appears screw-like because of interruption of subpellicular platelet layer by equatorial kinety and extrusome girdle ("body whorls"). Macronuclear nodules 36-72 in number. Equatorial kinety composed of monokinetids with short cilia, originates left of oral cavity and spirals around body in 4-5 helical turns towards posterior cell pole. Short ventral kinety usually on dorsal side between equatorial kinety and posterior pole, consisting of 12-15 nonciliated dikinetids. Adoral zone of membranelles discontinuous, composed of 12-18 anterior and 12-22 ventral adoral membranelles. Paroral membrane on right in oral cavity. Girdle of short (exact length not given) extrusomes parallel to equatorial kinety. Swims rather rapidly in zig-zag trajectory. Size of fixed specimens 44-110 x 20-60 µm. Retains functional chloroplasts from algal food and is thus mixotrophic (Laval-Peuto and Rassoulzadegan, 1988).
Ref.: Fauré-Fremiet (1924), Montagnes et al. (1988b), Lynn and Gilron (1993).