Athersuch & Horne, 1987
Carapace large, 0.7-0.85 mm long, elongate subreniform. Dorsal margin weakly convex with a straight or weakly concave posterior section, ventral margin moderately sinuous, anterior and posterior margins rounded. Greatest height at or a little behind mid-length. Fused zone relatively narrow in female, broad in male. Distal process of male copulatory appendage subquadrate to subtriangular with a broadly rounded anterior free corner and a small protrusion on the posterior free corner (S. rudjakovi 3 ).
Rudjakov (1962) considered his specimens from the White Sea to be conspecific with S. contortus sensu Brady (1868b), which he named S. bradyi , distinguishing it from the true contortus. Athersuch & Horne (1987) showed Rudjakov's species to be distinct from Brady's illustrated form, but conspecific with other specimens in the Brady and Norman collections as well as with S. contortus sensu Elofson (1941) and Wagner (1957), and accordingly named it S. rudjakovi.
S. rudjakovi is closely similar to S. contortus in details of carapace and appendages; S. rudjakovi is less elongate, has a more rounded dorsal margin and a relatively narrower fused zone in both sexes, and the distal process of its male copulatory appendage is relatively narrower.
Southern North Sea to the White Sea.