Halymenia a genus of a macroscopic red algae that grows in oceans worldwide. It includes the following species: * E.Y.Dawson * M.A.Howe * (J.Agardh) De Toni * Gargiulo, de Masi & Tripodi * E.Y.Dawson * S.M.P.B.Guimarães & M.T.Fujii * G.M.Smith & Hollenberg * * C.O.Acleto * I.A.Abbott & Kraft * E.C.Oliveira, Pinheiro-Vieira & R.E.Norris * I.A.Abbott * J.Agardh * Zanardini * Bory de Saint-Vincent * (J.Agardh) Kylin * Bory de Saint-Vincent * F.S.Collins & M.A.Howe * C.Agardh * Bory de Saint-Vincent * Zanardini * F.Schmitz * (Clemente) C.Agardh * J.Agardh * W.R.Taylor * Harvey ex Kützing * (Kylin) P.G.Parkinson * W.R.Taylor * J.Agardh * Hernández-Kantun & A.R.Sherwood * I.A.Abbott * Ercegovic * Dickie * M.A.Howe & W.R.Taylor