Octocannoididae Bouillon, Boero & Seghers, 1991

Wang, Xuefeng, Lu, Liyi, Zhang, Shenzeng, Lin, Linkun, Xu, Zhenzu, Guo, Donghui & Huang, Jiaqi, 2021, Two new species of hydromedusa (Cnidaria) from the Leizhou Bay, the northern South China Sea, Zoological Systematics 46 (3), pp. 193-199 : 197

Family Octocannoididae Bouillon, Boero & Seghers, 1991

Octocannoididae Bouillon, Boero & Seghers, 1991: 399–407 ; Bouillon et al., 2006: 359; Xu et al., 2007: 687–688; Xu et al., 2014: 631; Xu et al., 2019: 144–145, 160–161.

Diagnosis. Manubrium with or without gastric peduncle; mouth with 4 or 8 simple lips; 4 or 8 simple radial canals present; 4 or 8 marginal tentacles and 16–32 short club-shaped tentaculae present, all with black pigmented spots in marginal; without excretory papillae; gonad consisting of two lateral halves; with numerous statocysts; without ocelli.

Remarks. The family Octocannoididae was erected by Bouillon et al. (1991) based on Octocannoides ocellata Menon, 1932 , which had been placed in the families Phialuciidae or Malagazziidae ( Kramp, 1961; Bouillon, 1984). Based on the diagnosis of Octocannoididae, Xu et al. (2007, 2019 ) erected another two genera, i.e. Tetracannoides and Pedunculus , and modified the diagnosis of the family. However, the scientific name “ Pedunculus ” was preoccupied by an insect group ( Townes, 1969). Thus, a new name, Stylogastria Xu, Huang & Guo , nom. nov. is erected to replace Pedunculus Xu, Huang & Guo, 2019 . And the monotype of the genus was combined as Stylogastria polycystis (Xu, Huang & Guo, 2019) comb. nov. The scientific name of the genus refers to the gastrostyle on manubrium.

At present time, the family Octocannoididae medusa comprises three genera: Octocannoides Menon, 1932 , Tetracannoides Xu, Huang & Guo, 2007 and Stylogastria Xu, Huang & Guo , nom. nov.

Key to the genera of Octocannoididae medusa.

1. Manubrium with gastric peduncle; 8 radial canals, 8 marginal tentacles and 16–24 short club-shaped tentaculae present; 8 gonads developed near base of gastric peduncle .......................................................................... Stylogastria Xu, Huang & Guo , nom. nov. Manubrium without gastric peduncle................................................................................................................................................... 2

2. With 8 radial canals; manubrium with or without 8 radial lobes; 8 gonads on the radial canals and 8 simple oral lips present............. ............................................................................................................................................................... Octocannoides Menon, 1932 With 4 radial canals; manubrium with 4 radial lobes; 4 gonads present on each side of radial lobe; 4 oral lips short bifurcated, without terminal knob of cnidocysts ................................................................................................ Tetracannoides Xu, Huang & Guo, 2007