Acrochaete parasitica Oltmanns, 1894 accepted as Ulvella parasitica (Oltmanns) R.Nielsen, C.J.O'Kelly & B.Wysor, 2013 (basis of record)
Alaria grandifolia J.Agardh, 1872 accepted as Alaria esculenta (Linnaeus) Greville, 1830 (additional source)
Antithamnion americanum (Harvey) Kjellman, 1883 accepted as Scagelia americana (Harvey) Athanasiadis, 1996 (basis of record)
Antithamnionella pylaisaei (Mont.) Kjellm. accepted as Antithamnion pylaisaei (Montagne) Kjellman, 1883 accepted as Scagelia pylaisaei (Montagne) M.J.Wynne, 1985 (basis of record)
Audouinella spetsbergensis (Kjellman) Woelkerling, 1973 accepted as Meiodiscus spetsbergensis (Kjellman) G.W.Saunders & McLachlan, 1991 (basis of record)
Blidingia chadefaudii (Feldmann) Bliding, 1963 (additional source)
Chaetomorpha atrovirens W.R.Taylor, 1937 accepted as Chaetomorpha picquotiana Montagne ex Kützing, 1849 (basis of record)
Chaetomorpha cannabina (Areschoug) Kjellman, 1889 (basis of record)
Chlorochytrium cohnii E.P.Wright, 1877 (additional source)
Chlorochytrium dermatocolax Reinke, 1889 (additional source)
Chlorochytrium moorei N.L.Gardner, 1917 accepted as Halochlorococcum moorei (N.L.Gardner) Kornmann & Sahling, 1983 accepted as Halochlorococcum moorei (N.L.Gardner) Kornmann & Sahling ex Guiry, 2017 (basis of record)
Choreocolax rabenhorstii Reinsch, 1875 (basis of record)
Cladophora crystallina (Roth) Kützing, 1843 (additional source)
Colaconema membranacea (Magnus) Woelkerling, 1973 (basis of record)
Colaconema polyidis (Rosenvinge) Woelkerling, 1971 accepted as Helminthora divaricata (C.Agardh) J.Agardh, 1852 (basis of record)
Colaconema secundatum (Lyngbye) Woelkerling, 1973 accepted as Acrochaetium secundatum (Lyngbye) Nägeli, 1858 (basis of record)
Cruoria arctica F.Schmitz, 1893 accepted as Turnerella pennyi (Harvey) F.Schmitz, 1893 (basis of record)
Dumontia incrassata (O.F.Müller) J.V.Lamouroux, 1813 accepted as Dumontia contorta (S.G.Gmelin) Ruprecht, 1850 (additional source)
Ectocarpus penicillatus (C.Agardh) Kjellman, 1890 (basis of record)
Ectochaete wittrockii (Wille) Kylin, 1938 accepted as Ulvella wittrockii (Wille) R.Nielsen, C.J.O'Kelly & B.Wysor, 2013 (basis of record)
Elachista lubrica Ruprecht, 1850 accepted as Elachista fucicola (Velley) Areschoug, 1842 (basis of record)
Enteromorpha compressa (Linnaeus) Nees, 1820 accepted as Ulva compressa Linnaeus, 1753 (additional source)
Enteromorpha groenlandica (J.Agardh) Setchell & N.L.Gardner, 1920 accepted as Pseudothrix groenlandica (J.Agardh) Hanic & S.C.Lindstrom, 2008 (additional source)
Entonema aecidioides (Rosenvinge) Kylin, 1947 accepted as Laminariocolax aecidioides (Rosenvinge) A.F.Peters, 1998 (basis of record)
Entonema alariae (Jaasund) Jaasumd, 1965 (basis of record)
Entonema effusum (Kylin) Kylin, 1947 accepted as Punctaria tenuissima (C.Agardh) Greville, 1830 (basis of record)
Entonema polycladum (Jaasund) Jaasund, 1965 (basis of record)
Fucus edentatus Bachelot Pylaie, 1830 accepted as Fucus distichus subsp. edentatus (Bachelot Pylaie) H.T.Powell, 1957 (basis of record)
Gelidium crinale (Hare ex Turner) Gaillon, 1828 (additional source)
Giffordia granulosa (Smith) Hamel, 1939 accepted as Hincksia granulosa (Smith) P.C.Silva, 1987 (basis of record)
Goniotrichium alsidii (Zanardini) M.A. Howe, 1914 accepted as Goniotrichum alsidii (Zanardini) M.A.Howe, 1914 accepted as Stylonema alsidii (Zanardini) K.M.Drew, 1956 (basis of record)
Halosacciocolax lundii Edelstein, 1972 accepted as Rhodophysema lundii (Edelstein) C.W.Schneider & M.J.Wynne, 2019 (basis of record)
Halosaccion ramentaceum (Linnaeus) J.Agardh, 1852 accepted as Devaleraea ramentacea (Linnaeus) Guiry, 1982 (basis of record)
Lithophyllum corallinae (P.Crouan & H.Crouan) Heydrich, 1897 (basis of record)
Melobesia farinosa J.V.Lamouroux, 1816 accepted as Hydrolithon farinosum (J.V.Lamouroux) Penrose & Y.M.Chamberlain, 1993 (basis of record)
Melobesia lejolisii Rosanoff, 1866 accepted as Pneophyllum fragile Kützing, 1843 (additional source)
Monostroma pulchrum Farlow, 1881 accepted as Protomonostroma undulatum f. pulchrum (Farlow) M.J.Wynne, 1986 (basis of record)
Myriotrichia filiformis Harvey, 1841 accepted as Myriotrichia clavaeformis Harvey, 1834 (basis of record)
Ochlochaete ferox Huber, 1893 accepted as Ochlochaete hystrix var. ferox (Huber) R.Nielsen, 1978 (basis of record)
Pantoneura baerii (Ruprecht) Kylin, 1924 accepted as Pantoneura fabriciana (Lyngbye) M.J.Wynne, 1997 accepted as Membranoptera fabriciana (Lyngbye) M.J.Wynne & G.W.Saunders, 2012 (additional source)
Petrocelis hennedyi (Harvey) Batters, 1890 accepted as Haemescharia hennedyi (Harvey) K.L.Vinogradova & Yacovleva, 1989 (basis of record)
Petrocelis middendorfii (Ruprecht) Kjellman, 1883 (basis of record)
Phyllophora traillii Holmes ex Batters, 1890 accepted as Erythrodermis traillii (Holmes ex Batters) Guiry & Garbary, 1990 (basis of record)
Phyllophora truncata (Pallas) A.D.Zinova, 1970 accepted as Coccotylus truncatus (Pallas) M.J.Wynne & J.N.Heine, 1992 (additional source)
Phymatolithon rugulosum W.H.Adey, 1964 (basis of record)
Pilinia endophytica F.S.Collins, 1908 accepted as Ulvella repens (Pringsheim) R.Nielsen, C.J.O'Kelly & B.Wysor, 2013 (basis of record)
Platoma bairdi (Farlow) Kuckuck, 1912 accepted as Platoma bairdii (Farlow) Kuckuck, 1912 accepted as Tsengia bairdii (Farlow) K.C.Fan & Y.P.Fan, 1962 (basis of record)
Polysiphonia novae-angliae W.R.Taylor, 1937 accepted as Melanothamnus harveyi (Bailey) Díaz-Tapia & Maggs, 2017 (additional source)
Polysiphonia urceolata (Lightfoot ex Dillwyn) Greville, 1824 accepted as Polysiphonia stricta (Mertens ex Dillwyn) Greville, 1824 (additional source)
Pseudendoclonium submarinum Wille, 1901 (additional source)
Pseudopringsheimia fucicola (Rosenvinge) Wille, 1909 accepted as Pseudendoclonium fucicola (Rosenvinge) R.Nielsen, 1980 (additional source)
Ralfsia bornetii Kuckuck, 1894 accepted as Stragularia clavata (Harvey) Hamel, 1939 (additional source)
Ralfsia clavata (Carmichael ex Harvey) P.Crouan & H.Crouan, 1867 accepted as Stragularia clavata (Harvey) Hamel, 1939 (basis of record)
Rhodophyllis dichotoma (Lepechin) Gobi, 1878 accepted as Fimbrifolium dichotomum (Lepechin) G.I.Hansen, 1980 (additional source)
Solieria tenera (J.Agardh) M.J.Wynne & W.R.Taylor, 1973 accepted as Solieria filiformis (Kützing) P.W.Gabrielson, 1985 (basis of record)
Sphacelaria britannica Sauvageau, 1901 accepted as Sphacelaria nana Nägeli ex Kützing, 1855 accepted as Sphacelorbus nanus (Nageli ex Kützing) Draisma, Prud'homme & H.Kawai, 2010 (basis of record)
Sphacelaria furcigera Kützing, 1855 accepted as Sphacelaria rigidula Kützing, 1843 (basis of record)
Spongomorpha spinescens (Kützing) Kützing, 1854 accepted as Acrosiphonia spinescens (Kützing) Kjellman, 1893 (basis of record)
Streblonema immersum Levring, 1937 accepted as Microspongium immersum (Levring) P.M.Pedersen, 1984 (basis of record)
Streblonema oligosporum Strömfelt, 1884 accepted as Litosiphon laminariae (Lyngbye) Harvey, 1849 (additional source)
Ulothrix pseudoflacca Wille, 1901 accepted as Ulothrix flacca (Dillwyn) Thuret, 1863 (basis of record)
Ulvaria oxysperma (Kützing) Bliding, 1969 accepted as Gayralia oxysperma (Kützing) K.L.Vinogradova ex Scagel et al., 1989 (basis of record)