Acinetospora Bornet, 1891 (basis of record)
Acinetospora crinita (Carmichael) Sauvageau, 1899 (basis of record)
Acrochaete N.Pringsheim, 1862 accepted as Ulvella P.L.Crouan & H.M.Crouan, 1859 (basis of record)
Acrochaete leptochaete (Huber) R.Nielsen, 1983 accepted as Ulvella leptochaete (Huber) R.Nielsen, C.J.O'Kelly & B.Wysor, 2013 (basis of record)
Acrochaete viridis (Reinke) R.Nielsen, 1979 accepted as Ulvella viridis (Reinke) R.Nielsen, C.J.O'Kelly & B.Wysor, 2013 (basis of record)
Acrochaete wittrockii (Wille) R.Nielsen, 1983 accepted as Ulvella wittrockii (Wille) R.Nielsen, C.J.O'Kelly & B.Wysor, 2013 (basis of record)
Acrosiphonia J.Agardh, 1846 (basis of record)
Acrosiphonia arcta (Dillwyn) Gain, 1912 (basis of record)
Acrosiphoniaceae S. Jónsson, 1959 (additional source)
Alsidium C.Agardh, 1827 (basis of record)
Alsidium corallinum C.Agardh, 1827 (basis of record)
Antithamnion Nägeli, 1847 (basis of record)
Antithamnion cruciatum (C.Agardh) Nägeli, 1847 (basis of record)
Antithamnion heterocladum Funk, 1955 (basis of record)
Antithamnion tenuissimum (Hauck) Schiffner, 1915 (basis of record)
Arthrocladia Duby, 1830 (basis of record)
Arthrocladia villosa (Hudson) Duby, 1830 (basis of record)
Arthrocladiaceae Chauvin, 1842 (basis of record)
Bangia Lyngbye, 1819 (basis of record)
Bangiaceae Duby, 1830 (basis of record)
Blastophysa Reinke, 1889 (basis of record)
Blastophysa rhizopus Reinke, 1889 (basis of record)
Blidingia Kylin, 1947 (basis of record)
Blidingia marginata (J.Agardh) P.J.L.Dangeard ex Bliding, 1963 (basis of record)
Blidingia minima (Nägeli ex Kützing) Kylin, 1947 (basis of record)
Bolbocoleon Pringsheim, 1863 (basis of record)
Bolbocoleon piliferum Pringsheim, 1862 (basis of record)
Boodleaceae Børgesen, 1925 (basis of record)
Bornetia Thuret, 1855 (basis of record)
Bornetia secundiflora (J.Agardh) Thuret, 1855 (basis of record)
Brongniartella Bory de Saint-Vincent, 1822 (basis of record)
Brongniartella byssoides (Goodenough & Woodward) F.Schmitz, 1893 accepted as Vertebrata byssoides (Goodenough & Woodward) Kuntze, 1891 (basis of record)
Bryopsidaceae Bory de Saint-Vincent, 1829 (basis of record)
Bryopsis J.V.Lamouroux, 1809 (basis of record)
Bryopsis adriatica (J.Agardh) Frauenfeld, 1854 accepted as Bryopsis cupressina var. adriatica (J.Agardh) M.J.Wynne, 2005 (basis of record)
Bryopsis cupressina J.V.Lamouroux, 1809 (basis of record)
Bryopsis duplex De Notaris, 1844 (basis of record)
Bryopsis hypnoides J.V.Lamouroux, 1809 (basis of record)
Bryopsis plumosa (Hudson) C.Agardh, 1823 (basis of record)
Callithamnion Lyngbye, 1819 (basis of record)
Callithamnion corymbosum (Smith) Lyngbye, 1819 (basis of record)
Callithamnion granulatum (Ducluzeau) C.Agardh, 1828 (basis of record)
Capsosiphon Gobi, 1879 (basis of record)
Capsosiphon fulvescens (C.Agardh) Setchell & N.L.Gardner, 1920 (basis of record)
Capsosiphonaceae V.J. Chapman, 1952 (basis of record)
Caulerpa J.V.Lamouroux, 1809 (basis of record)
Caulerpa prolifera (Forsskål) J.V.Lamouroux, 1809 (basis of record)
Caulerpaceae Kützing, 1843 (basis of record)
Caulerpales (basis of record)
Ceramiaceae Dumortier, 1822 (basis of record)
Ceramiales (basis of record)
Ceramium Roth, 1797 (basis of record)
Ceramium ciliatum (J.Ellis) Ducluzeau, 1806 (basis of record)
Ceramium cimbricum H.E.Petersen, 1924 (basis of record)
Ceramium circinatum (Kützing) J.Agardh, 1851 (basis of record)
Ceramium codii (H.Richards) Mazoyer, 1938 accepted as Stirkia codii (H.Richards) Barros-Barreto & Maggs, 2023 (basis of record)
Ceramium deslongchampsii Chauvin ex Duby, 1830 (basis of record)
Ceramium diaphanum (Lightfoot) Roth, 1806 (basis of record)
Ceramium echionotum J.Agardh, 1844 (basis of record)
Ceramium flaccidum (Harvey ex Kützing) Ardissone, 1871 accepted as Gayliella flaccida (Harvey ex Kützing) T.O.Cho & L.J.McIvor, 2008 (basis of record)
Ceramium gaditanum (Clemente) Cremades, 1990 (basis of record)
Ceramium rubrum C.Agardh, 1811 accepted as Ceramium virgatum Roth, 1797 (basis of record)
Ceramium secundatum Lyngbye, 1819 (basis of record)
Ceramium siliquosum (Kützing) Maggs & Hommersand, 1993 (basis of record)
Ceramium tenerrimum (G.Martens) Okamura, 1921 accepted as Pseudoceramium tenerrimum (G.Martens) Barros-Barreto & Maggs, 2023 (basis of record)
Chaetomorpha Kützing, 1845 (basis of record)
Chaetomorpha aerea (Dillwyn) Kützing, 1849 (basis of record)
Chaetomorpha crassa (C.Agardh) Kützing, 1845 (basis of record)
Chaetomorpha gracilis Kützing, 1845 (basis of record)
Chaetomorpha ligustica (Kützing) Kützing, 1849 (basis of record)
Chaetomorpha linum (O.F.Müller) Kützing, 1845 (basis of record)
Chaetomorpha zernovii Woronichin, 1925 (basis of record)
Chaetopeltis Berthold, 1878 (basis of record)
Chaetopeltis orbicularis Berthold, 1878 (basis of record)
Chaetophoraceae Greville, 1824 (basis of record)
Chaetosiphonaceae Blackman & Tansley, 1902 (basis of record)
Chondria C.Agardh, 1817 (basis of record)
Chondria boryana (De Notaris ex J.Agardh) De Toni, 1903 (basis of record)
Chondria capillaris (Hudson) M.J.Wynne, 1991 (basis of record)
Chondria dasyphylla (Woodward) C.Agardh, 1817 (basis of record)
Chondrophycus (J.Tokida & Y.Saito) Garbary & J.T.Harper, 1998 (basis of record)
Chondrophycus paniculatus (C.Agardh) G.Furnari, 2000 accepted as Chondrophycus thuyoides (Kützing) G.Furnari, 2001 accepted as Palisada thuyoides (Kützing) Cassano, Sentíes, Gil-Rodríguez & M.T.Fujii, 2009 (basis of record)
Chondrophycus papillosus (C.Agardh) D.J.Garbary & J.T.Harper, 1998 accepted as Palisada perforata (Bory) K.W.Nam, 2007 (basis of record)
Chordariaceae Greville, 1830 (basis of record)
Choristocarpaceae Kjellman, 1891 (basis of record)
Choristocarpus Zanardini, 1860 (basis of record)
Choristocarpus tenellus Zanardini, 1860 (basis of record)
Chroothece Hansgirg, 1884 (basis of record)
Cladophora Kützing, 1843 (basis of record)
Cladophora albida (Nees) Kutzing, 1843 (basis of record)
Cladophora coelothrix Kützing, 1843 (basis of record)
Cladophora dalmatica Kützing, 1843 (basis of record)
Cladophora echinus (Biasoletto) Kützing, 1849 accepted as Lychaete echinus (Biasoletto) M.J.Wynne, 2017 (basis of record)
Cladophora fracta (O.F.Müller ex Vahl) Kützing, 1843 (basis of record)
Cladophora hutchinsiae (Dillwyn) Kützing, 1845 (basis of record)
Cladophora laetevirens (Dillwyn) Kützing, 1843 (basis of record)
Cladophora lehmanniana (Lindenberg) Kützing, 1843 (basis of record)
Cladophora liniformis Kützing, 1849 (basis of record)
Cladophora prolifera (Roth) Kützing, 1843 (basis of record)
Cladophora ruchingeri (C.Agardh) Kützing, 1845 (basis of record)