S. shangckuanu sp. nov. is characterized by its stout primary branches, flattened below and cylindrical above, very narrow leaves, generally entire at the margins, female receptacles compressed and two to three times bifurcate. This species is closely related to S. henslowianum, differing in its primary branches flattened below its receptaclar branchlets not indefinitely elongated, and its slightly compresed female receptacle.

S. frutescens sp. nov. is characterized by its conical holdfast, giving rise to four to eight caespitose main axes, each of which gives rise to one to three primary branches, each primary branch gives rise to numerous nearly equal secondary branches, thus giving the whole frond a characteristic bushy appearace; its small racemosely arranged receptacles are also characteristic. It is closely related to S. henslowianum and S. paniculatum differing in its female receptacles racemosely arranged similar to S. henslowianum, its male receptacles paniculately arranged on the fructiferous branchlets, similar to S. paniculatum, but its buchy habit differs with the two species.

S. fruticulosum sp. nov, is characterized by its flattened primary branches, glandular branchlets, and receptacles that are warty, cylindrical, and profusely paniculately arranged on the branchlets. This new species appears to be related to S. acinaria (Turn.) C. Agardh, especially in the report by Grunow of S. acinaria var. crassiuscula Grunow in the China Sea (Grunow 1915). In the arrangement of the receptacles, however, the present species has a typical racemose to subpaniculate inflorescence and is thus a member of siliquosae. These are complicated by the inflorescence, somewhat cymosely arranged in its younger stage.

S. guangdongu sp. nov. is characterized by its coarse frond, its losely branched, primary branches compressed below and cylindrical above, its very much larger basal leaves, and its shorter receptacular branchlets and absence of young receptacles on elongated axes. These characteristics make it easy to differentiate from other closely related species such as S. kenslowianum C. Agardh.

S. agaviforme sp. nov. is characterized by its primary branch arising from the axes and full of receptacular branchlets reminding one of the land plant agave with its flowering branches, hence the name “agaviforme”. The young basal leaves are commonly pinnatifid or forked. Each of the leaves has a slender, long stalk similar to that of S. kuetzingu but shorter; these characteristics make it easy to differentiate from closely related species such as S. kuetzingu.

S. leizhouense sp. nov, is characterized by its large basal dissected leaves, with upper leaves usually equal in length; the receptacles are subpaniculately arranged, the male ones elongated and iwarty, and the budlike structures arising from the upper parts on the main axes. It is close to S.paniculatum but differs in its dissected lower leaves, its copiously branched frond, and its compressed lower parts of the primary branches.