Cohn (1866: 280, figs 8–11)
Kahl (1930: 199); Petz et al. (1995: 55)
In vivo 150–250 × 45–80 µm. Body narrowly to broadly lanceolate; frontal portion bent dorsally, contractile; body laterally flattened, right side flat, left distinctly vaulted; undernourished specimens with 2–5 inconspicuous ridges on left side. Trichocyst warts on dorsal side, with a rope-like structure; rope-like structure also along ventral margin and posteriorly a short distance on dorsal side in the area of the cytostome. Right somatic kineties 11–21, densely ciliated (very few anteriorly shortened), 5–7 left kineties, 2 dorsolateral kineties. Brosse in anterior half of body, with bristle-like cilia. Perioral kineties 3, along entire ventral margin; row 2 also extends a short distance onto dorsal side. Extrusomes (trichocysts) rod-shaped, straight to gently curved, 13–16 µm long, along ventral margin and dorsally in warts. Macronuclear nodules 2; micronucleus 1. Contractile vacuole subterminal. Movement: slowly gliding.
Ross Sea, in the region 66.95°–74.77°S and 134.85°–165.02°W, in sea-ice (Petz, unpublished data); Weddell Sea (Petz et al., 1995); North Atlantic (Hamburger & Buddenbrock, 1911); White Sea (Mereschkowsky, 1879); North Sea (Kahl, 1930); Mediterr-anean Sea (Massutí Alzamora, 1929); Caspian Sea (Agamaliev, 1971); Arabian Gulf (Al-Rasheid, 1997); Pacific (Song, 1993).