Key to the genera of Bythotiaridae medusae of South China Sea. 1. Centripetal canals present, blindly ending or joining base of manubrium............................................................................................2 Without centripetal canals.................................................................................................................................................................... 3 2. All tentacles hollow; cnidocysts only in the terminal knob........................................................................... Calycopsis Fewkes, 1882 Two kinds of tentacles, large, hollow, with rings of cnidocysts and a terminal knob, and small, solid dwarf tentacles without terminal knob ................................................................................................................................................ Eumedusa Bigelow, 1920 3. Radial canals simple, unbranched ........................................................................................................................................................4 Radial canals branched; gonads folded or smooth ...............................................................................................................................6 4. Gonads smooth adradial ............................................................................................................................ Pseudotiara Bouillon, 1980 Gonads smooth interradial ...................................................................................................................................................................5 5. 8 radial canals; marginal tentacles with abaxial basal ocelli ........................................................................... Bythocellata Nair, 1951 4 radial canals; no ocelli............................................................................................................................. Protiaropsis Stechow, 1919 6. Radial canals branching repeatedly at various levels ........................................................................................... Sibogita Maas, 1905 Radial canals simple or bifurcated .......................................................................................................................................................7 7. 4 radial canals simple or bifurcated; gonads interradial, with transverse furrows; marginal bulbs absent ..... Bythotira Günther, 1903 2 simple and 2 bifurcated radial canals; gonads smooth perradial; marginal tentacles with basal swellings embedded in mesoglea .... ..................................................................................................................................................... Gymnogonium Xu & Huang, 1994

Published as part of Zhenzu Xu, Jiaqi Huang, Mao Lin, Donghui Guo & Chunguang Wang, 2016, Taxonomic notes on Hydroidomedusae (Cnidaria) from South China Sea II: Family Bythotiaridae (Anthomedusae), pp. 149-157 in Zoological Systematics 41 (2) on page 151, DOI: 10.11865/zs.2016013, http://zenodo.org/record/270289