Body almost rectangular, posteriorly rounded to slightly tapering, anteriorly distinctly convex, spur-like protrusion each on right and left side; usually 1 spine each dorsally near anterior end of dorsal kineties. Deeply caved in region of transverse and left marginal cirri. Pellicle rigid. Two macronuclear nodules connected by short funiculus, 1 micronucleus. Contractile vacuole anterior and right of transverse cirri. Six frontoventral, 4-5 transverse, 3 left marginal and 3 strong caudal cirri. Six dorsal kineties. Adoral zone of membranelles bipartite, 11 anterior and 5 posterior adoral membranelles. Undulating membrane almost surrounding very large oral area. Movement usually jumping and swimming very fast, rests with adoral membranelles and cirri rigidly spread; swims also slow and wobbly. Size in vivo usually 80-110 x 50-65 µm. Specimens having a nodulated C- or horseshoe-shaped macronucleus very likely belong to Uronychia heinrothi Buddenbrock, 1920 (for improved diagnosis see Petz et al., 1995a).
Ref.: Kahl (1932), Curds and Wu (1983), Hill (1990), Petz et al. (1995a).