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

Six new species of Coelostoma Brulle, 1835 are described from China: Coelostoma bannanicum 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. Coelostoma surkhetensis Hebauer, 2002 is a new record from China (Xizang). Coelostoma huangi Jia, Aston & Fikacek, 2014 is reported from Yunnan, C. hajeki Jia, Aston & Fikacek, 2014 from Hunan, C. jaechiJia, Lin, Chan, Skale & Fikacek, 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. Coelostoma transcaspicum Reitter, 1906 is excluded from Chinese fauna. Coelostoma sulcatum 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.