Taxonomic review of Rheocricotopus Brundin, 1956 (Diptera: Chironomidae: Orthocladiinae) from East Asia, with descriptions of twelve new species

East Asian species of Rheocricotopus are reviewed and 12 species are illustrated and described as new to science in the subgenus Psilocricotopus Sæther: R. (P.) albulus sp. nov., R. (P.) bannaensis sp. nov., R. (P.) beibengensis sp. nov., R. (P.) binotatus sp. nov., R. (P.) chinogodavarius sp. nov., R. (P.) fasciolatus sp. nov., R. (P.) hanmiensis sp. nov., R. (P.) masarui sp. nov., R. (P.) monovittatus sp. nov., R. (P.) nippobifasciatus sp. nov., R. (P.) protuberans sp. nov., and R. (P.) yunnanensis sp. nov. Additionally, the female adult, pupa and larva of R. (P.) togakuroasi (Sasa & Okazawa, 1992), the female adult and pupa of R. (P.) orientalis Wang, 1995, the larva of R. (s. str.) tamahumeralis Sasa, 1981, and the female adult, pupa and larva of R. (s. str.) togapeniculus Sasa & Okazawa, 1992 are described for the first time. In total, 28 new synonyms are given: Rheocricotopus nudisquamus Makarchenko & Makarchenko, 2009, R. brochus Liu, Lin & Wang, 2014 and R. longiligulatus Yamamoto & Yamamoto, 2017 are listed as junior synonyms of R. amamipubescius (Sasa, 1990), R. bifasciatus Wang & Zheng, 1991 and R. oiraprimus Sasa, 1991, respectively; R. chalybeatus bicoloratus Caspers & Reiss, 1989, R. emeiensis Wang & Zheng, 1989, R. nigrus Wang & Zheng, 1989, R. okifoveatus Sasa, 1990, R. tedorisecundus Sasa, 1994, R. isigadeeus Sasa & Suzuki, 2000, R. yakulemeus Sasa & Suzuki, 2000, R. inaquereus Sasa, Kitami & Suzuki, 2001, R. inaxeyeus Sasa, Kitami & Suzuki, 2001, R. taiwanensis Wang, Yan & Maa, 2004, R. heterochros Liu, Song & Wang, 2014, and R. nemoacrostichalis Chaudhuri & Sinharay, 1983 are treated as junior synonyms of R. chalybeatus (Edwards, 1929); R. akagisecundus Kikuchi & Sasa, 1994 and R. gotocedeus Sasa & Suzuki, 2001 are treated as junior synonyms of R. togakuroasi (Sasa & Okazawa, 1992); R. baishanensis Wang & Zheng, 1991 and R. himalayenis Chaudhuri & Sinharay, 1983 are treated as junior synonyms of R. effusus (Walker, 1856); R. reduncusoides Namayandeh & Beresford, 2018 and R. shofukusecundus Sasa, 1998 are treated as junior synonyms of R. reduncus Sæther & Schnell, 1988 and Paracladius akansextus Sasa & Kaminura, 1987, respectively; R. kamimonji Sasa & Hirabayashi, 1993 and R. kurocedeus Sasa, 1996 are treated as junior synonyms of R. togapeniculus Sasa & Okazawa, 1992; Parorthocladius negoroi Yamamoto, 2011 and Orthocladius piloculatus Kobayashi, 2012 are treated as junior synonyms of Parorthocladius intermedius (Tokunaga, 1939) comb. nov.; R. tobatervicesimus Kikuchi & Sasa, 1990, Paratrichocladius unabrevis Sasa, 1996 and R. rotundus Liu, Lin & Wang, 2014 are treated as junior synonyms of Paracricotopus irregularis Niitsuma, 1990. In addition, two new combinations, Parorthocladius intermedius (Tokunaga, 1939) comb. nov. and Paracricotopus brachypus (Wang & Zheng, 1991) comb. nov. are proposed here. To accommodate these species, generic and subgeneric diagnoses are emended. A key to the known male adults from East Asia is provided.