中国介螅水母属二新种(丝螅水母目,介螅水母科)

Two new species of genus Hydractinia from China(Filifera,Hydractiniidae)

记述了台湾海峡及其邻近海区介螅水母科Hydractiniidae L.Agassiz,1862介螅水母属Hydractinia van Beneden,1841二新种,即螺旋介螅水母,新种Hydractinia spiralis sp. nov.和反曲介螅水母,新种Hydractinia recurvatus sp.nov.,兹将二新种主要鉴别特征描述于下:螺旋介螅水母,新种:伞无顶突;垂管长圆柱形,约为内伞腔深度2/3;口腕简单,末端具成束刺胞;生殖腺很大,呈椭圆形,几乎覆盖整个垂管间辐位,无水母芽;缘触手6条,4条主辐位,另2条仅在相对间辐位,基球延长锥状,同样大小,无眼点,触手长,近端2/3粗壮,远端1/3变细,具螺旋状刺胞。反曲介螅水母,新种:伞无顶突;垂管短小,呈方形;胃柄显著,约为垂管长度1/2;口有4个主辐位口唇,延长成向上反曲的短口腕,末端具成丛刺胞;4个卵圆形生殖腺,附在二个反曲口腕之间的垂管间辐位,无水母芽;缘触手16条,触手基球膨大,呈锥状,同样大小,整条触手具环状刺胞,末端略膨大,呈椭圆形。

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, elliptic-like, 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, quadratic-shaped 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 oval-shaped 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.