Genus: Body long to ovoid; apex fan-shaped; txicysts evenly distributed along edge of apex (Illustrated Guide, 1985).
Body elongate, circular in cross section; antrerior obliquely truncated, surmounted by an unciliated apical ridge,
which is lined with trichocysts; cytostome slit-like (Carey, 1992).
Very many species (Corliss, 1979).
Species: Cell body ovoid, rotund, 255 μm long, with a well-developed anterior (apical ridge thick), macronucleus ellipsoidal (Carey, 1992).
Images of collecting locality:
Yasuragi-no-ike (pond), Oura central park, Oura town, Gunma Pref., Japan, February 2006 by Y. Tsukii
S. syrtis Lepsi, 1964: Cell body ovoid, rotund, 255 μm long, with a well-developed anterior (apiccal ridge thick), macronucleus ellipsoidal (Carey, 1992).
S. extensum Kahl, 1933: cell body long and tubular, 200-250 μm long, anterior truncate and expanded, posterior rounded, trichocyst present in the anterior, macronucleus long and moniliform (Carey, 1992).