1. Genus Halecium Oken, 1815
2. Genus Nemalecium Bouillon, 1986
3. Genus Baleum Billard, 1929 accepted as Halecium Oken, 1815
4. Genus Diplocyathus Allman, 1888 accepted as Hydrodendron Hincks, 1874 (unaccepted > junior subjective synonym, synonym)
5. Genus Endothecium Fraser, 1935 accepted as Halecium Oken, 1815 (preoccupied by Endothecium Koker,1924 [Anthozoa])
6. Genus Georginella Hadzi, 1914 accepted as Hydranthea Hincks, 1868 (synonym)
7. Genus Haloikema Bourne, 1890 accepted as Halecium Oken, 1815 (synonym)
8. Genus Ophiodes Hincks, 1866 accepted as Ophiodissa Stechow, 1919 accepted as Hydrodendron Hincks, 1874 (preoccupied by several other names, e. g. Ophiodes Wagler, 1824 [reptiles])
9. Genus Ophiodissa Stechow, 1919 accepted as Hydrodendron Hincks, 1874 (synonym)
10. Genus Phylactotheca Stechow, 1913 accepted as Hydrodendron Hincks, 1874 (synonym)
11. Genus Sacculina Bale, 1919 accepted as Saaba Stechow, 1923 (invalid junior homonym of Sacculina Thompson, 1836 [Crustacea])
12. Genus Sagamihydra Hirohito, 1995 accepted as Halecium Oken, 1815
13. Genus Scoresbia Watson, 1969 accepted as Hydrodendron Hincks, 1874 (synonym)
14. Genus Thoa Lamouroux, 1816 accepted as Halecium Oken, 1815 (synonym)
15. Genus Hemitheca Hilgendorf, 1898 (uncertain > nomen dubium)
16. Genus Hydrella Goette, 1880 (uncertain > taxon inquirendum)
17. Genus Saaba Stechow, 1923 (uncertain > taxon inquirendum, replacement name for preoccupied Sacculina Bale, 1919)

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