Two new species of Platynectes Régimbart, 1879 from China with notes on other Chinese members of the genus, including a key to species (Coleoptera: Dytiscidae: Agabinae).

Two new Platynectes species, P. maizuqii sp. nov. from Guangdong and P. pangu sp. nov. from Yunnan, are described. New records are provided for the following species: P. davidorum Hájek, Alarie, Stastný & Vondrácek, 2019 from Jiangxi, P. dissimilis (Sharp, 1873) from Guangxi, P. gemellatus Stastný, 2003 from Hunan and Zhejiang, P. kashmiranus lemberki Stastný, 2003 from Xizang and P. nanlingensis Stastný, 2003 from Jiangxi. Additional records are also given for most other Chinese species. Platynectes kashmiranus kashmiranus J. Balfour-Browne, 1944 is removed from the Chinese fauna. The habitus of all and the male genitalia of most species are illustrated. An updated key to all Chinese species of Platynectes is provided.

A review of Copelatus Erichson, 1832 of Mainland China, with description of ten new species from the japonicus complex (Coleoptera: Dytiscidae: Copelatinae).

The species of the genus Copelatus Erichson, 1832 from China Mainland are reviewed. 22 species are recorded in total. Ten new species: C. dentatipenis sp. nov. (Fujian, Hunan, Jiangxi), C. diversistriatus sp. nov. (Yunnan; Laos, Myanmar, Thailand), C. felicis sp. nov. (Yunnan), C. miaowangi sp. nov. (Guizhou), C. mopanshanensis sp. nov. (Yunnan), C. nanlingensis sp. nov. (Guangdong), C. puzhelongi sp. nov. (Yunnan; Laos, Vietnam), C. rosulae sp. nov. (Yunnan), C. tengchongensis sp. nov. (Yunnan), and C. xiniudong sp. nov. (Guizhou) are described. Copelatus chinensis Rgimbart, 1899 is reinstituted as a valid species with Copelatus collocallosus Falkenstrm, 1932 and C. collocallosus Falkenstrm, 1933 as its junior subjective synonyms. One species from Hongkong remains unidentified since it is so far known only from a limited number of females. Additional records are provided for the known species; three species: C. bacchusi Wewalka, 1981, C. malaisei Guignot, 1954 and C. parallelus Zimmermann, 1920 are recorded from China for the first time. Copelatus takakurai Sat, 1985 is withdrawn from the Chinese fauna. All species are diagnosed, and their habitus and male genitalia are illustrated. An updated identification key to Chinese Copelatus is provided.