Family: Body ellipsoidal, uniformly ciliated; hypostomial frange short; prominent cytopharyngeal apparatus
Genus: Oral aperture small, oval (Carey, 1992).
cell body μm long, μm wide,
with three or more contractile vacuoles,
x 640, Inari Park, Toyama city, Toyama Pref., Japan, September 2002, by Y. Tsukii
Nassula ornata Ehrenberg, 1833: 250 μm long, 180 μm wide (Kahl, 1931). Ovoid, 250 μm long; frange presents; a single contractile vacuole lie in the mid-body region; macronucleus with at least three micronuclei; many trichocysts present (Carey, 1992).
* Nassula aurea Ehrenberg, 1833: 250 μm long; L/W=2 (Kahl, 1931). Ovoid or elliptical, 250 μm long; reduced frange presents; long cytopharyngeal apparatus "cyrtos" presents; macronucleus with 2 to 4 micronuclei; a single contractile vacuole; trichocysts absent (Carey, 1992).
Nassula terminalis Ozaki & Yagiu, 1941: Ovoid, flattened and flexible; 150-210 μm long; anterior quarter narrower than the rest of the body; cytopharyngeal opening very long; macronucleus ovoid; single micronucleus; single contractile vacuole terminal; trichocysts absent (Carey, 1992).