Tregouboviopsis perradialis

Material examined. Holotype. 1 male, BG 001, Beibu Gulf, st. S 30 (17 ° 30 ' N, 107 ° 30 ' E), depth 70 m, 6 July 2008, coll. Xin Liang (SFRI). Other material. 1 female, SFI 002, central of South China Sea, st. ZI 8 (16 ° 31 ' N, 113 ° 21 ' E), depth 1395 m, sampling depth 240 – 0 m, 31 July 2014, coll. Lianggen Wang (SFRI). Diagnosis. Umbrella globular, mesoglea fairly thick; with 16 exumbrellar didermic centripetal tracks; mouth with 4 simple, long oral tentacles, arising above mouth rim, without terminal clusters and with ring nematocysts; 4 gonads very large, long and mass-like, almost covering perradial part along the whole length of manubrium; without marginal bulbs and tentacles. Description. Umbrella 6 mm high, 5.0 – 5.5 mm wide, globular, mesoglea fairly thick, marginal portion near as thick as apical portion; without free tentacles; along bell margin a ring of thickened tissue with nematocysts from which originate 16 didermic centripetal tracks (4 perradial, 4 interradial, 8 adradial) running meridionally on the surface of the exumbrella towards aboral pole, reaching maximally to mid umbrella; manubrium large and voluminous, reaching to level of velum, base square to cross-shaped, about 4 / 5 as long as subumbrella cavity, with 4 interradial subumbrella projections upper the manubrium; mouth quadratic with 4 simple, long oral tentacles, arising above mouth rim, unarmed terminal nematocyst clusters, but with ring nematocysts; four relatively thick radial canals and circular canal wide; mesenteries long, about 1 / 2 the length of manubrium connected to the radial canals by mesenteries; four gonads very large, long and mass-like, almost covering perradial part along the whole length of manubrium, well separated interradially, female with numerous very large eggs, without isolated pits of adradial series, but male with isolated pits of adradial series; without ocelli; velum wide. Distribution. Central and northern of South China Sea. Remarks. The species is rare as only two specimens were collected so far. The holotype male, collected from the northern South China Sea (Beibu Gulf), has following characters: 16 exumbrella didermic centripetal tracks present; mouth with 4 perradial oral tentacles arising above mouth rim, without terminal clusters and with ring nematocysts; 4 gonads in perradial position of manubrium, each with 2 adradial series of 4 – 5 isolated pits (male specimen) and no marginal tentacles (Figs 6 – 7). The female, another specimen collected from the central of South China Sea, has similar structures as the holotype but has 4 large, smooth gonads without isolated pits in longitudinal series (Figs 8 – 12) (see genus remarks).