1. Species Castagnea chordariaeformis (P.L.Crouan & H.M.Crouan) Thuret, 1888 accepted as Sauvageaugloia divaricata (Clemente) Cremades, 1990 (synonym)
2. Species Castagnea contorta Thuret, 1863 accepted as Cladosiphon contortus (Thuret) Kylin, 1940
3. Species Castagnea crassa (Suringar) Kuckuck, 1929 accepted as Tinocladia crassa (Suringar) Kylin, 1940 accepted as Eudesme crassa (Suringar) Okamura, 1935 accepted as Tinocladia crassa (Suringar) Kylin, 1940 (synonym)
4. Species Castagnea cylindrica Sauvageau accepted as Cladosiphon cylindricus (Sauvageau) Kylin, 1940
5. Species Castagnea divaricata (C.Agardh) J.Agardh, 1882 accepted as Sphaerotrichia divaricata (C.Agardh) Kylin, 1940
6. Species Castagnea filum (Harvey) Kuckuck, 1929 accepted as Cladosiphon filum (Harvey) Kylin, 1940
7. Species Castagnea fistulosa (Zanardini) Derbés & Solier, 1851 accepted as Cladosiphon mediterraneus Kützing, 1843
8. Species Castagnea griffithsiana (A.W.Griffiths ex Harvey) J.Agardh, 1882 accepted as Sauvageaugloia divaricata (Clemente) Cremades, 1990
9. Species Castagnea howei W.R.Taylor, 1928 accepted as Nemacystus howei (W.R.Taylor) Kylin, 1940
10. Species Castagnea ikomae Narita, 1936 accepted as Mesogloia ikomae (Narita) H.Kawai & T.Hanyuda, 2019
11. Species Castagnea irregularis Sauvageau accepted as Cladosiphon irregularis (Sauvageau) Kylin, 1949
12. Species Castagnea mediterranea (Kützing) Hauck accepted as Cladosiphon mediterraneus Kützing, 1843 (synonym)
13. Species Castagnea polycarpa Derbès & Solier, 1851 accepted as Cladosiphon mediterraneus Kützing, 1843 (synonym)
14. Species Castagnea ramosissima (Zanardini) Nasr, 1947 accepted as Myriogloea ramosissima (Zanardini) Papenfuss, 1968 (synonym)
15. Species Castagnea tuberculosa (Hornemann) J.Agardh, 1882 accepted as Stilophora nodulosa (C.Agardh) P.C.Silva, 1996
16. Species Castagnea vermicularis (Harvey) Kuckuck, 1929 accepted as Cladosiphon vermicularis (J.Agardh) Kylin, 1940
17. Species Castagnea virescens (Carmichael ex Harvey) Thuret, 1863 accepted as Eudesme virescens (Carmichael ex Berkeley) J.Agardh, 1882
18. Species Castagnea zosterae (J.Agardh) Thuret, 1863 accepted as Cladosiphon zosterae (J.Agardh) Kylin, 1940
19. Species Castagnea zosterae (Lyngbye) Thuret, 1863 accepted as Eudesme virescens (Carmichael ex Berkeley) J.Agardh, 1882
20. Species Castagnea pontica Woronichin, 1908 (uncertain, uncertain taxonomic status subjected to verification)

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