Hydractinia (Stylactis) ingolfi Kramp, 1932 accepted as Hydractinia ingolfi (Kramp, 1932)
Hydractinia allmanii Bonnevie, 1898 accepted as Schuchertinia allmanii (Bonnevie, 1898)
Hydractinia angusta Hartlaub, 1904
Hydractinia arctica (Jäderholm, 1902)
Hydractinia claviformis (Bouillon, 1965) accepted as Hydractinia proboscidea (Hincks, 1868)
Hydractinia cytaeiformis Vervoort, 2006
Hydractinia galeai Calder & Watling, 2021
Hydractinia gorgonoides (Nutting, 1906)
Hydractinia ingolfi (Kramp, 1932)
Hydractinia proboscidea (Hincks, 1868)
Hydrodendrium gorgonoides Nutting, 1906 accepted as Hydractinia gorgonoides (Nutting, 1906)
Latebrahydra schulzei Calder & Watling, 2021
Schuchertinia allmanii (Bonnevie, 1898)
Stylactis arctica Jäderholm, 1902 accepted as Hydractinia arctica (Jäderholm, 1902)
Stylactis claviformis Bouillon, 1965 accepted as Hydractinia claviformis (Bouillon, 1965) accepted as Hydractinia proboscidea (Hincks, 1868)
Stylactis vermicola Allman, 1888 accepted as Stylactella vermicola (Allman, 1888)