Abstract:Samples of Hydractinia collected from the Taiwan Strait at 20.85°N -27.06°N, 114.92°E -121.24°E during January and July 2007, and Beibu Bay at 17.06°N -21.57°N, 107.40°E -110.10°E during July 2006 to April 2007. Two new species of Hydractinia spiralis sp. nov. and Hydractinia recurvatus sp. nov. are described in the present paper based on the type specimens from the Taiwan Strait and Beibu Bay. The specific diagnosis of the two species is as follows: Hydractinia spiralis sp. nov. Umbrella without apical projection; manubrium cylindrical, about 2/3 of length of manubrium; oral arms simple, each with one terminal cnidocyst cluster; gonads very large, ellipticlike, covering whole interradial on manubrium, no medusa bud; with 6 tentacles, 4 perradial, 2 opposite interradial, all basal bulbs elongate conical, equal size without abaxial pigmented patch, tentacles very long, in the upper 2/3 of the proximal part of tentacle, thick and stout, evenly covered cnidocysts, and suddenly in the 1/3 of distal part of tentacles, tapered thin, with encircling spiral nematocysts. Hydractinia recurvatus sp. nov. Umbrella without apical projection; manubrium short and small, quadraticshaped with a conspicuous gastric peduncle, about 1/2 of length of manubrium; mouth with 4 perradial lips elongated to form very short, recurvate oral arms, each with terminal cnidocyst cluster; with 4 oval gonads interradial on manubrium wall, and about 1/2 of gonads ovalshaped attached on interradial position of manubrium at the place between recurvate oral arms, no medusa; up to 16 solid marginal tentacles with swollen, conical basal bulbs, and approximately from the same size, no ocelli; tentacle very long, evenly covered ring endocysts and a distinct terminal knob.