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).
Staining by A. Kihara
Stylonychia, cysts, x 100, x 400, x 640, April 1999, by Y. Tsukii