Petz (1995: 134, fig. 40)
In vivo 50–65 × 40–55 µm. Body cornucopia-shaped, covered by a posteriorly open hyaline ‘lorica’. Somatic kineties 4, short, longitudinally radiating from near posterior pole, without a cytoplasmic flap. Adoral membranelles 19–21 external, continuous with 4 or 5 distinct internal membranelles in a closed spiral; rightmost internal membranelle enlarged. Macronuclear nodules 2; micronuclei 2. Contractile vacuole in posterior third of body. Movement: slow to moderately fast, rarely very rapid, rotating about main body axis, often swimming backwards. Secretes a mucous thread at antapical end when undisturbed and attaches to substratum, remains rotating on the spot; disturbed individual immediately detaches from thread and darts away.
Ross Sea, in the region 68.98°–76.60°S and 162.43°–164.85°W, in surface plankton (Petz, unpublished data); Weddell Sea (Petz et al., 1995).