Carapace medium to large, 0.6-0.75 mm long, elongate subreniform. Dorsal margin weakly convex with almost straight anterior, central and posterior sections, ventral margin moderately sinuous, anterior and posterior margins rounded. Greatest height well behind mid-length. Fused zone relatively broad. Male smaller, relatively higher posteriorly and with a broader fused zone than female. Distal process of male copulatory appendage relatively large, subtriangular, with a broadly rounded anterior free corner (S. contortus 9 ).
S. contortus may be distinguished from similar elongate British species by careful comparison of carapace outlines; S. whatleyi and S. bradyi are both relatively higher and have narrower fused zones, while S. schornikovi is more produced anteriorly and posteriorly. S. rudjakovi more closely resembles S. contortus both in carapace outline and in the shape of the male copulatory appendage, but the former species is slightly less elongate with a more rounded dorsal margin and a rather narrower fused zone, and the distal process of its male copulatory appendage is relatively narrower than that of S. contortus.
British Isles. All previous records of S. contortus must be treated with suspicion; the only undoubted living record is from the Isle of Skye.