(Montagnes & Taylor) Petz, Song & Wilbert (1995: 139, fig. 41)
Strobilidium neptuni Montagnes & Taylor (1994: 572, figs 1–3)
In vivo 35–60 µm diameter. Body bowl-shaped, posteriorly broadly rounded. Somatic kineties 5; kineties 1 and 3–5 ±longitudinal; kinety 2 forms an arc on posterior left-lateral side beginning and ending at kinety 1. Adoral zone of membranelles composed of 36–40 external and 1 or 2 internal membranelles in a closed spiral. Macronucleus horseshoe-shaped; micronuclei 2. Movement: very fast, sometimes jumping, remains stationary in-between and rotating about main body axis, appears helicopter-like in top view.
Ross Sea, in the region 68.98°–76.60°S and 162.43°–164.85°W, in the plankton (Petz, unpublished data); Weddell Sea (Petz et al., 1995); North Pacific (Montagnes & Taylor, 1994).