Liagora ceranoides, originally described from the Virgin Islands in the Caribbean Sea, has been widely reported from the Indo-Pacific but can easily be confused with other species/genera of the Liagoraceae in the field. In this study, we examined the vegetative and reproductive morphology of L. ceranoides-like specimens from Taiwan and New Caledonia in the western Pacific Ocean and from Western Australia in the eastern Indian Ocean, and we inferred their phylogenetic relationships along with related genera on the basis of rbcL sequence analyses. The molecular analyses demonstrated that the L. ceranoides-like specimens clustered into two distantly related clades that were characterized reproductively: clade I possessed unfused postfertilization carpogonial-branch cells and slightly diffuse gonimoblasts and clade II (including specimens from the type region of L. ceranoides) had fused postfertilization carpogonial-branch cells and compact gonimoblasts. We therefore proposed the new genus and species Yoshizakia indopacifica to include the specimens identified in clade I. Our phylogenetic analyses indicated that Liagoracean genera with relatively long involucral filaments and unfused carpogonial branches were closely related. Yoshizakia was readily separated from related genera by a combination of the behaviour of the carpogonial-branch cells and the development of involucral filaments and gonimoblasts following presumed fertilization. In addition, our rbcL sequence analyses have confirmed the previously suggested occurrence in the northeast Indian Ocean and the southwest Pacific Ocean of Titanophycus setchellii, Neoizziella asiatica and Macrocarpus perennis, all originally described from the northern or central Pacific Ocean.