Genus: Marginal cirri not confluent at rear; oral cavity wide, expansive; caudal cirri (usually 3) prominent (Illustrated Guide, 1985). Cell body ovoid to elongate, inflexible; large AZM supported anteriorly by a collar; two rows of marginal cirri not confluent posteriorly; strongly-developed frontoventral & transverse cirri present; three long, stiff caudal cilia; dorsal surface ornamented by short rows of cirri; two macronuclei; cyst stage recorded in some species (Carey, 1992). 8 (3 + 2 + 3) frontal, 5 ventral, 5 transverse, 3 caudal cirri. Species: 100-300 μm long (Kudo, 1966). Elongate, anterior wider than posterior; up to 300 μm long; AZM 1/3 to 1/2 body length; distinctive 3 frontal and 3 long caudal cirri; two ovoid macronuclei (Carey, 1992).

50 μm 100 μm 150 μm; x 400 : 31 μm 63 μm 94 μm; x 640

31 μm 63 μm 94 μm; x 640

Stylonychia mytilus, cell body μm long, μm wide, x 400, x 640, Saitama Pref., Japan 2000, by Y. Tsukii
50 μm 100 μm 150 μm; x 400 : 31 μm 63 μm 94 μm; x 640

Stylonychia mytilus, a conjugating pair, cell body μm long, μm wide, x 400, Saitama Pref., Japan 2000, by Y. Tsukii
50 μm 100 μm 150 μm; x 400