Valbonesi & Luporini (1990b: 50, figs 8–12)
In vivo 60–100 × 40–60 µm. Body broadly ellipsoidal, with a small spur-like projection on anterior right in c. 50% of specimens, 1 or 2 conspicuous ventral and 6–9 dorsal ridges, dorsoventrally flattened; pellicle rigid. Cirri: 10 frontoventral, 5 or 6 transverse, 2 or 3 left-marginal, 2 or 3 caudal. Dorsal kineties 11 (or 12) (13–21 dikinetids in mid-dorsal rows). Adoral membranelles 26–35. Macronucleus horseshoe- to C-shaped, rarely inverted J-like; micronucleus 1. Contractile vacuole 1. Dorsal silverline system of double-eurystomus type. Movement: crawling moderately quickly, interrupted by resting. Specimens can encyst rapidly.
Brackish pools on shore of Ross Sea (Valbonesi & Luporini, 1990b).
This species has also been found in freshwater lakes in Victoria Land, in the region 74.33°–74.70°S and 164.12°–165.12°E (Petz & Valbonesi, unpublished data), and on Byers Peninsula, Livingston I. (South Shetland Is.) at about 62°38’S 61°04’W (Petz & Quesada, unpublished data).