• Capsicarpella elongata Bory de Saint-Vincent, 1923
• Capsicarpella speciosa Kjellman, 1872 accepted as Haplospora globosa Kjellman, 1872
• Capsicarpella sphaerospora (Carmichael ex Harvey) Bory de Saint-Vincent accepted as Isthmoplea sphaerophora (Carmichael) Gobi, 1878
• Ectocarpidium caliacrae Celan
• Ectocarpidium pitraeanum Sperk, 1869
• Ectocarpus abbreviatus Kützing, 1843 accepted as Ectocarpus fasciculatus var. abbreviatus (Kützing) Sauvageau, 1892
• Ectocarpus acanthophorus Kützing
• Ectocarpus acuminatus De A.Saunders, 1898 accepted as Feldmannia acuminata (De A.Saunders) Hollenberg & I.A.Abbott, 1966
• Ectocarpus acuto-ramulis Noda, 1969 accepted as Hincksia acutoramulis (Noda) R.X.Luan, 2009
• Ectocarpus acutus Setchell & N.L.Gardner, 1922
• Ectocarpus acutus var. acutus Setchell & Gardner, 1922 accepted as Ectocarpus fasciculatus Harvey, 1841
• Ectocarpus acutus var. haplogloiae Doty, 1947
• Ectocarpus adriaticus Ercegovic, 1955
• Ectocarpus adriaticus f. maior Ercegovic, 1955
• Ectocarpus aecidioides Rosenvinge, 1893 accepted as Laminariocolax aecidioides (Rosenvinge) A.F.Peters, 1998
• Ectocarpus affinis Setchell & N.L.Gardner, 1922
• Ectocarpus aleuticus Kützing, 1860
• Ectocarpus amicorum Harvey accepted as Ectocarpus indicus Sonder, 1854 accepted as Feldmannia indica (Sonder) Womersley & A.Bailey, 1970
• Ectocarpus amphibius Harvey, 1848 accepted as Ectocarpus siliculosus var. subulatus (Kützing) T.Gallardo, 1992 accepted as Ectocarpus siliculosus var. dasycarpus (Kuckuck) Gallardo, 1992
• Ectocarpus antillarum Grunow, 1868 accepted as Bachelotia antillarum (Grunow) Gerloff, 1959
• Ectocarpus approximatus Kützing, 1849 accepted as Ectocarpus flagelliformis Kützing, 1843
• Ectocarpus approximatus var. ceratoides (Kützing) Grunow, 1867 accepted as Ectocarpus flagelliformis Kützing, 1843
• Ectocarpus approximatus var. flagelliformis (Kützing) Grunow, 1867 accepted as Ectocarpus flagelliformis Kützing, 1843
• Ectocarpus arabicus Figari & De Notaris, 1853 accepted as Feldmannia irregularis (Kützing) Hamel, 1939
• Ectocarpus arabicus Kützing, 1855 accepted as Feldmannia irregularis (Kützing) Hamel, 1939
• Ectocarpus arachnoideus Zanardini (uncertain)
• Ectocarpus arctus Kützing, 1843 accepted as Ectocarpus siliculosus var. arctus (Kützing) Gallardo, 1992
• Ectocarpus auratus Bory de Saint-Vincent ex Kützing, 1849
• Ectocarpus balakrishnanii V.Krishnamurthy, 2000
• Ectocarpus barbadensis Kuckuck, 1963
• Ectocarpus battersii Bornet ex Sauvageau, 1895 accepted as Kuetzingiella battersii (Bornet ex Sauvageau) Kornmann, 1956
• Ectocarpus battersii var. mediterranea Sauvageau accepted as Kuetzingiella battersii var. mediterranea (Sauvageau) Gómez & Ribera, 1992
• Ectocarpus battersiides Ercegovic, 1955 accepted as Feldmannia battersiides (Ercegovic) Cormaci & G.Furnari, 1987
• Ectocarpus battersiides f. maior Ercegovic, 1955 accepted as Feldmannia battersiides f. maior (Ercegovic) Antolic & Span, 2010
• Ectocarpus battersiides f. sporangiosessilis Ercegovic, 1955 accepted as Feldmannia battersiides f. sporangiosessilis (Ercegovic) Antolic & Span, 2010
• Ectocarpus battersiides f. taoniae Ercegovic, 1955 accepted as Feldmannia battersiides f. taoniae (Ercegovic) Antolic & Span, 2010
• Ectocarpus berteroanus Montagne, 1852
• Ectocarpus bombycinus Kützing, 1849
• Ectocarpus borealis (Kjellman) Kjellman, 1890
• Ectocarpus bornetii Hamel (uncertain)
• Ectocarpus bracchiolus Lindauer, 1949
• Ectocarpus brachiatus (C.Agardh) C.Agardh, 1824 accepted as Pylaiella littoralis (Linnaeus) Kjellman, 1872
• Ectocarpus brachiatus (Smith) S.F.Gray, 1821 (uncertain)
• Ectocarpus brachiatus Harvey, 1841 accepted as Stictyosiphon griffithsianus (Le Jolis) Holmes & Batters, 1890
• Ectocarpus breviarticulatus J.Agardh, 1847 accepted as Asteronema breviarticulatum (J.Agardh) Ouriques & Bouzon, 2000
• Ectocarpus brevicellularis Noda, 1975
• Ectocarpus brevis Sauvageau, 1892 accepted as Streblonema breve (Sauvageau) De Toni, 1895
• Ectocarpus bryantii Setchell & N.L.Gardner, 1924 accepted as Hincksia bryantii (Setchell & N.L.Gardner) J.N.Norris, 2001
• Ectocarpus caespitulus J.Agardh, 1842 accepted as Feldmannia lebelii (Areschoug ex P.Crouan & H.Crouan) Hamel, 1939
• Ectocarpus caespitulus Kjellman, 1872 accepted as Feldmannia kjellmanii Kylin, 1947
• Ectocarpus caliacrae Celan, 1938
• Ectocarpus capensis Kützing, 1849
• Ectocarpus caspicus A.Henckel, 1909
• Ectocarpus castaneus Kützing (uncertain)
• Ectocarpus ceratoides Kützing, 1849 accepted as Ectocarpus flagelliformis Kützing, 1843
• Ectocarpus chalybeus (Roth) Lyngbye, 1819 accepted as Audouinella chalybaea (Roth) Bory de Saint-Vincent, 1823
• Ectocarpus chantransioides Setchell & N.L.Gardner, 1922
• Ectocarpus chapmanii Lindauer, 1960
• Ectocarpus chiloensis Reinsch (uncertain)
• Ectocarpus chitonicola De A.Saunders, 1898 accepted as Feldmannia chitonicola (De A.Saunders) Levring, 1960
• Ectocarpus chnoosporae Børgesen, 1924
• Ectocarpus chordariae Farlow, 1881 accepted as Streblonema chordariae (Farlow) De Toni, 1895
• Ectocarpus cladosiphoniae Noda, 1969
• Ectocarpus clandestinus (P.Crouan & H.Crouan) Sauvageau, 1892 accepted as Myriactula clandestina (P.Crouan & H.Crouan) Feldmann, 1945
• Ectocarpus clavifer J.Agardh, 1854
• Ectocarpus columellaris Børgesen, 1936 accepted as Feldmannia columellaris (Børgesen) Islam, 1976
• Ectocarpus commensalis Setchell & N.L.Gardner, 1922
• Ectocarpus commixtus Noda, 1972
• Ectocarpus compactus (Roth) C.Agardh, 1828 accepted as Pylaiella littoralis (Linnaeus) Kjellman, 1872
• Ectocarpus compactus var. densissimus C.Agardh, 1828 accepted as Pylaiella littoralis (Linnaeus) Kjellman, 1872
• Ectocarpus confervoides Harvey, 1855
• Ectocarpus confervoides Le Jolis, 1863 accepted as Ectocarpus siliculosus (Dillwyn) Lyngbye, 1819
• Ectocarpus confervoides f. arctus (Kützing) Kjellman, 1872 accepted as Ectocarpus siliculosus (Dillwyn) Lyngbye, 1819
• Ectocarpus confervoides f. crassus Kjellman, 1890 accepted as Ectocarpus siliculosus var. dasycarpus (Kuckuck) Gallardo, 1992
• Ectocarpus confervoides f. dasycarpa (Kuckuck) Rosenvinge & Lund accepted as Ectocarpus siliculosus var. dasycarpus (Kuckuck) Gallardo, 1992
• Ectocarpus confervoides f. dasycarpus (Kuckuck) Rosenvinge & Lund, 1941 accepted as Ectocarpus siliculosus var. dasycarpus (Kuckuck) Gallardo, 1992
• Ectocarpus confervoides f. hiemalis P.Crouan & H.Crouan ex Kjellman, 1872 accepted as Ectocarpus siliculosus var. hiemalis (P.L.Crouan & H.M.Crouan) Gallardo, 1992
• Ectocarpus confervoides f. irregularis F.S.Collins, 1906 accepted as Ectocarpus siliculosus (Dillwyn) Lyngbye, 1819
• Ectocarpus confervoides f. parvus Setchell & Gardner, 1922 accepted as Ectocarpus parvus (De A.Saunders) Hollenberg, 1971 accepted as Ectocarpus commensalis Setchell & N.L.Gardner, 1922
• Ectocarpus confervoides f. penicillatus (C.Agardh) Kjellman, 1872 accepted as Ectocarpus penicillatus (C.Agardh) Kjellman, 1890
• Ectocarpus confervoides f. pygmaeus (Areschoug) Kjellman, 1890 accepted as Ectocarpus siliculosus var. pygmaeus (Areschoug) Gallardo, 1992
• Ectocarpus confervoides f. siliculosus (Dillwyn) Kjellman, 1872 accepted as Ectocarpus siliculosus (Dillwyn) Lyngbye, 1819
• Ectocarpus confervoides f. spalatinus (Kützing) Kjellman, 1872 accepted as Ectocarpus siliculosus (Dillwyn) Lyngbye, 1819
• Ectocarpus confervoides f. subulatus (Kützing) Stechell & N.L.Gardner, 1922 accepted as Ectocarpus siliculosus var. subulatus (Kützing) T.Gallardo, 1992 accepted as Ectocarpus siliculosus var. dasycarpus (Kuckuck) Gallardo, 1992
• Ectocarpus confervoides f. variabilis D.A.Saunders, 1898 accepted as Ectocarpus commensalis Setchell & N.L.Gardner, 1922
• Ectocarpus confervoides f. variabilis Saunders, 1898
• Ectocarpus confervoides var. arctus (Kützing) Lily Newton, 1931 accepted as Ectocarpus siliculosus (Dillwyn) Lyngbye, 1819
• Ectocarpus confervoides var. brumalis Holden accepted as Ectocarpus siliculosus (Dillwyn) Lyngbye, 1819
• Ectocarpus confervoides var. corticulatus (Saunders) Saunders, 1901 accepted as Ectocarpus corticulatus De A.Saunders, 1898
• Ectocarpus confervoides var. crouaniorum (Thuret) A.Cardinal, 1964 accepted as Ectocarpus crouaniorum Thuret, 1863
• Ectocarpus confervoides var. hiemalis (Foslie) Farlow
• Ectocarpus confervoides var. longipes Harvey
• Ectocarpus confervoides var. pygmaeus (Areschoug) Rosenvinge, 1893 accepted as Ectocarpus siliculosus var. pygmaeus (Areschoug) Gallardo, 1992
• Ectocarpus confervoides var. siliculosus (Dillwyn) Farlow, 1881 accepted as Ectocarpus siliculosus (Dillwyn) Lyngbye, 1819
• Ectocarpus confusiophyllus Noda, 1969
• Ectocarpus congestus P.L.Crouan & H.M.Crouan, 1867 accepted as Ectocarpus fasciculatus var. congestus (P.L.Crouan & H.M.Crouan) Batters, 1902
• Ectocarpus congregatus Zanardini
• Ectocarpus conifer Børgesen, 1914 accepted as Hincksia conifera (Børgesen) I.A.Abbott, 1989
• Ectocarpus coniger Børgesen, 1935 accepted as Feldmannia irregularis (Kützing) Hamel, 1939
• Ectocarpus coniger var. arabicus Nasr, 1941 accepted as Feldmannia irregularis (Kützing) Hamel, 1939