Carapace large, 0.7-0.94 mm long, subquadrate to subreniform. Dorsal margin weakly convex with straight anterior, central and posterior sections, ventral margin weakly sinuous, anterior and posterior margins broadly rounded. Greatest height well behind mid-length. Fused zone relatively narrow. Male smaller and relatively a little higher posteriorly than female. Distal process of male copulatory appendage relatively large, subtriangular (S. bradyi 3 ).
Rudjakov (1962) established S. bradyi for S. contortus sensu Brady (1868b), which he believed to be conspecific with his own specimens from the White Sea. Athersuch & Horne (1987) demonstrated that Brady's and Rudjakov's forms were not conspecific, and named the White Sea species S. rudjakovi ; both species do occur in British waters.
S. bradyi may be distinguished from other British species by its large size and rather quadrate carapace outline; S. whatleyi has a similar outline but is more produced anteriorly.
Known only from British waters (NE England, Firth of Clyde and the Shetland Islands).