Additional fauna of Coelostoma Brullé, 1835 from China, with re-establishment of Coelostomasulcatum Pu, 1963 as a valid species (Coleoptera, Hydrophilidae, Sphaeridiinae)

Six new species of Coelostoma Brullé, 1835 are described from China: Coelostomabannanicum Mai & Jia, sp. nov., C.dactylopunctum Mai & Jia, sp. nov., C.fortunum Mai & Jia, sp. nov., and C.pseudomartensi Mai & Jia, sp. nov. from Yunnan; C.mixtum Mai & Jia, sp. nov. from Fujian; and C.nankunshanense Mai & Jia, sp. nov. from Guangdong. Coelostomasurkhetensis Hebauer, 2002 is a new record from China (Xizang). Coelostomahuangi Jia, Aston & Fikáček, 2014 is reported from Yunnan, C.hajeki Jia, Aston & Fikáček, 2014 from Hunan, C.jaechi Jia, Lin, Chan, Skale & Fikáček, 2017 from Guangdong, C.turnai Hebauer, 2006 from Fujian, Guizhou and Chongqing, and C.wui Orchymont, 1940 from Shanxi and Zhejiang, all for the first time. Coelostomatranscaspicum Reitter, 1906 is excluded from Chinese fauna. Coelostomasulcatum Pu, 1963 is confirmed as a valid species and its variations of aedeagus are illustrated. The specimens treated as C.wui Orchymont, 1940 by previous authors possibly contain two species. The diversity and habitats of Chinese Coelostoma are discussed. A modified key to the species of Chinese Coelostoma is provided.