Some new Hydroidomedusa (Cnidaria) from the northern South China Sea Author Wang, Xuefeng College of Fisheries, Guangdong Ocean University, Zhanjiang 524088, China Author Lin, Kun College of Fisheries, Guangdong Ocean University, Zhanjiang 524088, China Author Xu, Zhenzu College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China Corresponding author, E-mail: guodh @ xmu. edu. cn Author Guo, Donghui College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China Corresponding author, E-mail: guodh @ xmu. edu. cn Author Huang, Jiaqi College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China Corresponding author, E-mail: guodh @ xmu. edu. cn text Zoological Systematics 2019 44 3 191 205 journal article 10.11865/zs.201923 2095-6827 5366458 DC69BC63-5B4D-4851-9A40-715353079BFC Family Eucodoniidae Schuchert, 1996 Eucodoniidae Schuchert, 1996: 88–89 ; Bouillon et al. , 2006: 147 ; Lin et al. , 2016: 49 . Diagnosis. The family is diagnosed by: medusae without apical projection; umbrella bell-shaped; no exumbrellar cnidocyst tracks; manubrium on conical gastric peduncle; mouth quadrangular, with 4 inconspicuous cnidocyst-armed lips; with 4 radial canals and circular canal; gonads completely surrounding manubrium; medusae budding from stomach; without mesenteries; 2 or 4 perradial marginal bulbs and 2 or 4 tentacles with or without terminal swelling; no ocelli. Remarks. The family Eucodoniidae was erected by Schuchert (1996) . Schuchert (1996) and Bouillon et al. (2006) provided a generic diagnosis for the monotypic family Eucodoniidae by having four tentacles and four marginal bulbs, based on Eucodonium brownei Hartlaub, 1907 . Contrasting to E. brownei , Lin et al. (2016) reported another 3 new species of Eucodonium in the South China Sea by having only two tentacles, two marginal bulbs, and other two opposite rudimentary bulbs. Therefore, the diagnosis of the family was modified.