1. Species Spermothamnion antillarum Stegenga & Vroman, 1987
2. Species Spermothamnion cymosum (Harvey) De Toni, 1903
3. Species Spermothamnion echigoense Noda, 1972
4. Species Spermothamnion endophytica Okamura, 1934
5. Species Spermothamnion flabellatum Bornet, 1876
6. Species Spermothamnion gymnocarpum M.A.Howe, 1920
7. Species Spermothamnion intricatum (C.Agardh) De Toni, 1903
8. Species Spermothamnion investiens (P.L.Crouan & H.M.Crouan) Vickers, 1905
9. Species Spermothamnion irregulare (J.Agardh) Ardissone, 1883
10. Species Spermothamnion johannis Feldmann-Mazoyer, 1941
11. Species Spermothamnion macromeres F.S.Collins & Hervey, 1917
12. Species Spermothamnion miniatum Huisman, 1985
13. Species Spermothamnion nonatoi A.B.Joly, 1957
14. Species Spermothamnion orientale Weber-van Bosse, 1923
15. Species Spermothamnion pinnatum E.M.Gordon, 1972
16. Species Spermothamnion repens (Dillwyn) Magnus, 1873
17. Species Spermothamnion strictum (C.Agardh) Ardissone, 1883
18. Species Spermothamnion barbatum (C.Agardh) Bornet, 1892 accepted as Ptilothamnion pluma (Dillwyn) Thuret, 1863 (synonym)
19. Species Spermothamnion capitatum Bornet, 1892 accepted as Tiffaniella capitata (Bornet) Doty & Meñez, 1960
20. Species Spermothamnion cladophorae Yamada & T.Tanaka, 1934 accepted as Ptilothamnion cladophorae (Yamada & T.Tanaka) G.Feldmann-Mazoyer, 1941
21. Species Spermothamnion codicola Yamada & T.Tanaka, 1934 accepted as Tiffaniella codicola (Yamada & T.Tanaka) Doty & Meñez, 1960
22. Species Spermothamnion cymodoceae Børgesen, 1952 accepted as Tiffaniella cymodoceae (Børgesen) E.M.Gordon, 1972
23. Species Spermothamnion feldmanniae P.Huvé, 1972 accepted as Tiffaniella feldmanniae (P.Huvé) Gillis & Coppejans, 1982
24. Species Spermothamnion gorgoneum (Montagne) Bornet, 1896 accepted as Tiffaniella gorgonea (Montagne) Doty & Meñez, 1960
25. Species Spermothamnion mesocarpum (Carmichael) Chemin accepted as Ptilothamnion pluma (Dillwyn) Thuret, 1863 (synonym)
26. Species Spermothamnion phycophilum W.R.Taylor, 1945 accepted as Tiffaniella phycophila (W.R.Taylor) E.M.Gordon, 1972
27. Species Spermothamnion pusillum Okamura & Segawa, 1936 accepted as Ptilothamnion pusillum (Okamura & Segawa) Itono, 1977
28. Species Spermothamnion roseolum (C.Agardh) Pringsheim, 1862 accepted as Spermothamnion repens (Dillwyn) Magnus, 1873
29. Species Spermothamnion saccorhiza (Setchell & N.L.Gardner) Feldmann-Mazoyer, 1942 accepted as Tiffaniella saccorhiza (Setchell & N.L.Gardner) Doty & Meñez, 1960
30. Species Spermothamnion schmitzianum E.S.Barton, 1893 accepted as Tiffaniella schmitziana (E.S.Barton) Bolton & Stegenga, 1987
31. Species Spermothamnion snyderae Farlow, 1899 accepted as Tiffaniella snyderae (Farlow) I.A.Abbott, 1971
32. Species Spermothamnion speluncarum (F.S.Collins & Hervey) M.A.Howe, 1920 accepted as Ptilothamnion speluncarum (F.S.Collins & Hervey) D.L.Ballantine & M.J.Wynne, 1998 (synonym)
33. Species Spermothamnion suyehioroi (Okamura) Okamura, 1934 accepted as Tiffaniella suyehioroi (Okamura) Kaneko, 1976
34. Species Spermothamnion tamamiru Segawa, 1938 accepted as Tiffaniella tamamiru (Segawa) E.M.Gordon, 1972
35. Species Spermothamnion turneri (Mertens ex Roth) Areschoug, 1845 accepted as Scagelothamnion turneri (Mertens ex Roth) Athanasiadis, 2016 (synonym)
36. Species Spermothamnion yonakuniensis Yamada & T.Tanaka, 1938 accepted as Gordoniella yonakuniensis (Yamada & T.Tanaka) Itono, 1977
37. Species Spermothamnion boergesenii V.Krishnamurthy, 1998 (uncertain)
38. Species Spermothamnion inordinatum (Zanardini) Hauck, 1885 (uncertain, uncertain taxonomic status subjected to verification)
39. Species Spermothamnion umamaheswarae V.Krishnamurthy, 1998 (uncertain)

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