Family: Cyrtos in rear 1/2 of body, hidden by ventral pellicular fold.
Genus: Cytostome in rear 1/3 of body (Illustrated Guide, 1985).
Irregular, almost triangular in shape; anterior pointed; posterior rounded;
distinctly flattened with a delicate keeled armour; somatic ciliation reduced;
ventrally 3 longitudinal cilary rows; cytostome in a depression at posterior ventral region;
tooth-like projection on the left side
(Carey, 1992).