The taxonomic status of the genus Stylactaria Stechow, 1921 (Hydroidomedusae, Anthomedusae, Hydractiniidae), with the description of a new species

The status of all the species ascribed in the literature to Stylactaria is discussed, that nominal genus is considered a congener of Hydractinia and a new species (Hydractinia calderi n. sp.) is described. The medusae of the medusabased genera Hansiella and Tregoubovia, formerly ascribed to the Hydractiniidae, are shown to be more like the medusae of Thecocodium, a genus having ptilocodiid hydroids. Both Hansiella and Tregoubovia are thus transferred to the Ptilocodiidae. With their removal from the Hydractiniidae, a redefinition of both families is provided. The genus Fiordlandia is considered as synonym of Clavactinia.