Genus: Postoral kineties usually to left of oral poykinetids (Illustrated Guide, 1985). Left edge is more curved than right edge; cytopharynx with numerous strong fibrils; ectoplasm with numerous fusiform trichocysts; macronucleus oval; one to several micronulei (Kudo, 1966). Species: 150-600 μm long; ventrally flattened; dark colored; buccal cavity close to anterior end (How to know the protozoa, 1979). Elongate 150-600 μm long; anterior is not wider than posterior; cytostome small with well defined pre- and postoral suture; a large macronucleus with three micronuclei; single contractile vacuole with 12 radiating canals; many trichocysts (Carey, 1992). Cell body 150-600 μm long (Kahl, 1930).

100 μm 200 μm 400 μm; x 100 ; 50 μm 100 μm 200 μm; x 200

16 μm 32 μm 63 μm; x 640

Frontonia leucas, stock Cos-1, stained with Azure C, macronucleus ellipsoidal, 70-72 μm long, 35 μm wide, elongated type 87 μm long, 26 μm wide, micronuclei spindle-shaped, 7 μm long, 1.8-2.2 μm wide, DV images, x 640, Omachi natural park, Ichikawa city, Chiba Pref., Japan, September 2001 by Y. Tsukii
16 μm 32 μm 63 μm; x 640

PhotoCD images
Frontonia leucas, stock Cos-1, macronucleus ellipsoidal, 90 μm long, 52 μm wide, micronuclei spindle-shaped, 7 μm long, 3 μm wide, x 640, Japan, 2002 by Y. Tsukii
31 μm 63 μm 94 μm; x 640