Genus: Body blunt at rear; kineties spiralled when body contracts (Illustrated Guide, 1985).
1-3 mm long (without expansion or attenuation); peristome 2/3 body length; macronucleus moniliform; size and the length of the peristome separate this species from S. intermedium (600 μm long , peristome1/2 the body length) (Carey, 1992).

S. ambiguum x 100	S. intermedium in prep.	S. teres x 100