• Cystoseira C.A. Agardh, 1820
• Cystoseira abies-marina (S.G. Gmelin) C. Agardh, 1820
• Cystoseira abrotanifolia (Linnaeus) C. Agardh, 1820 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830
• Cystoseira acanthophora Schiffner, 1926 accepted as Cystoseira schiffneri G. Hamel, 1939
• Cystoseira adriatica Sauvageau, 1912 accepted as Cystoseira spinosa Sauvageau, 1912
• Cystoseira algeriensis Feldmann, 1945
• Cystoseira amentacea (C. Agardh) Bory de Saint-Vincent, 1832
• Cystoseira articulata J.G. Agardh, 1848 accepted as Hormophysa cuneiformis (J.F. Gmelin) P.C. Silva, 1987
• Cystoseira aurantia Kützing, 1843 accepted as Cystoseira concatenata (Linnaeus) C. Agardh, 1820 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830
• Cystoseira australis C. Agardh
• Cystoseira axillaris (Turner) C. Agardh
• Cystoseira baccata (S.G. Gmelin) P.C. Silva, 1952
• Cystoseira balearica Sauvageau, 1912 accepted as Cystoseira brachycarpa J.G. Agardh, 1896
• Cystoseira banksii (Turner) C. Agardh, 1820 accepted as Hormosira banksii (Turner) Decaisne, 1842
• Cystoseira barbata (Stackhouse) C. Agardh, 1820
• Cystoseira barbatula Kützing, 1860
• Cystoseira billardieri (Bory) Endlicher
• Cystoseira boryana (Kützing) Meneghini
• Cystoseira bosphorica Sauvageau, 1912 accepted as Cystoseira crinita Duby, 1830
• Cystoseira brachycarpa J.G. Agardh, 1896
• Cystoseira brownii (Turner) C. Agardh, 1820 accepted as Cystophora brownii (Turner) J.G. Agardh, 1848
• Cystoseira caespitosa Sauvageau, 1912 accepted as Cystoseira brachycarpa J.G. Agardh, 1896
• Cystoseira canariensis Sauvageau, 1912 accepted as Cystoseira humilis Schousboe ex Kützing, 1860
• Cystoseira caudata C. Agardh
• Cystoseira cephalornithos (Labill.) C. Agardh
• Cystoseira compressa (Esper) Gerloff & Nizamuddin, 1975
• Cystoseira concatenata (Linnaeus) C. Agardh, 1820 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830
• Cystoseira corniculata (Turner) Zanardini, 1841
• Cystoseira crassipes (Mertens ex Turner) C. Agardh, 1821
• Cystoseira crinita Duby, 1830
• Cystoseira crinitophylla Ercegovic, 1952
• Cystoseira decipiens (R. Brown ex Turner) C. Agardh, 1821 accepted as Sargassum decipiens (R. Brown ex Turner) J.G. Agardh, 1873
• Cystoseira discors (Linnaeus) C. Agardh, 1828 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830
• Cystoseira divaricata Kützing
• Cystoseira dorycarpa (Turner) C. Agardh
• Cystoseira douglasii Harvey, 1840 accepted as Stephanocystis osmundacea (Turner) Trevisan, 1843 accepted as Cystoseira osmundacea (Turner) C. Agardh, 1820
• Cystoseira dubia Valiante, 1883
• Cystoseira dumosa Greville ex Sonder, 1846 accepted as Cystophora dumosa (Greville ex Sonder) J.G. Agardh, 1870
• Cystoseira elata Kützing
• Cystoseira elegans Sauvageau, 1912
• Cystoseira ensifolia C. Agardh, 1824 accepted as Sargassum ensifolium (C. Agardh) J.G. Agardh, 1873
• Cystoseira epiphytica Schiffner ex Gerloff & Nizamuddin, 1976
• Cystoseira ercegovicii Giaccone, 1973 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830
• Cystoseira erica-marina (S.G. Gmelin) Naccari, 1828 accepted as Cystoseira spinosa Sauvageau, 1912
• Cystoseira ericoides (Linnaeus) C. Agardh, 1820 accepted as Cystoseira tamariscifolia (Hudson) Papenfuss, 1950
• Cystoseira expansa C. Agardh, 1824 accepted as Stephanocystis osmundacea (Turner) Trevisan, 1843 accepted as Cystoseira osmundacea (Turner) C. Agardh, 1820
• Cystoseira fibrosa (Hudson) C. Agardh, 1820 accepted as Cystoseira baccata (S.G. Gmelin) P.C. Silva, 1952
• Cystoseira filicina Bory de Saint-Vincent accepted as Cystoseira compressa (Esper) Gerloff & Nizamuddin, 1975
• Cystoseira filifolia (C. Agardh) C. Agardh
• Cystoseira fimbriata Bory de Saint-Vincent, 1832 accepted as Cystoseira compressa (Esper) Gerloff & Nizamuddin, 1975
• Cystoseira flabellata Schousboe
• Cystoseira flaccida Kützing, 1843
• Cystoseira foeniculacea (Linnaeus) Greville, 1830
• Cystoseira fucoides Ercegovic, 1952 accepted as Cystoseira dubia Valiante, 1883
• Cystoseira funkii Schiffner ex Gerloff & Nizamuddin, 1976
• Cystoseira geminata C. Agardh, 1824
• Cystoseira gerloffi Nizamuddin, 1978 accepted as Cystoseira spinosa Sauvageau, 1912
• Cystoseira gerloffii Nizamuddin
• Cystoseira gibraltarica (Sauvageau) P. Dangeard, 1949 accepted as Cystoseira mauritanica Sauvageau, 1911
• Cystoseira glomerata Kützing
• Cystoseira gracilis Kützing
• Cystoseira graeca Schiffner ex Gerloff & Nizamuddin, 1975 accepted as Cystoseira barbatula Kützing, 1860
• Cystoseira granulata C. Agardh, 1820
• Cystoseira grevillei C. Agardh ex Sonder, 1846 accepted as Cystophora grevillei (C. Agardh ex Sonder) J.G. Agardh, 1848
• Cystoseira hakodatensis (Yendo) Fensholt, 1952
• Cystoseira helvetica Heer, 1877
• Cystoseira hoppii C. Agardh, 1820 accepted as Cystoseira barbata (Stackhouse) C. Agardh, 1820
• Cystoseira humilis Schousboe ex Kützing, 1860
• Cystoseira hyblaea Giaccone, 1985
• Cystoseira hypocarpa Kützing, 1854
• Cystoseira indica (Thivy & Doshi) Mairh, 1968
• Cystoseira jabukae Ercegovic, 1952
• Cystoseira latifrons (Kützing) De Toni, 1895 accepted as Hormophysa cuneiformis (J.F. Gmelin) P.C. Silva, 1987
• Cystoseira lepidium Ruprecht, 1850
• Cystoseira leptocarpa Kützing
• Cystoseira linearifolia Schousboe
• Cystoseira macrocarpa Kützing, 1854
• Cystoseira masoudii M. Nizamuddin, 1995
• Cystoseira mauritanica Sauvageau, 1911
• Cystoseira mediterranea Sauvageau, 1912
• Cystoseira melanothrix (Kützing) Piccone, 1884
• Cystoseira microcarpa Kützing
• Cystoseira montagnei J.G. Agardh, 1842
• Cystoseira mucronata (Turner) Gaillon
• Cystoseira muricata C. Agardh, 1820 accepted as Cystoseira trinodis (Forsskål) C. Agardh, 1820
• Cystoseira myrica (S.G. Gmelin) C. Agardh, 1820
• Cystoseira myriophylloides Sauvageau, 1912 accepted as Cystoseira humilis Schousboe ex Kützing, 1860
• Cystoseira neglecta Setchell & N.L. Gardner, 1917
• Cystoseira nigra Bory de Saint-Vincent
• Cystoseira nodicaulis (Withering) M. Roberts, 1967
• Cystoseira nodularia (Mertens) C. Agardh, 1820 accepted as Hormophysa cuneiformis (J.F. Gmelin) P.C. Silva, 1987
• Cystoseira occidentalis Gardner, 1923
• Cystoseira oligacantha (Kützing) Harvey
• Cystoseira oligacantha Kützing
• Cystoseira opuntioides Bory de Saint-Vincent ex Montagne, 1846 accepted as Cystoseira zosteroides C. Agardh, 1820
• Cystoseira ornithocephala Sprengel
• Cystoseira osmundacea (Turner) C. Agardh, 1820
• Cystoseira paniculata (Turner) C. Agardh
• Cystoseira pappafaviana Zanardini
• Cystoseira paradoxa (Turner) C. Agardh