Moth flies (Diptera: Psychodidae) of the western Hercynian mountains, Sokolov open-cast coal mines and dumps (Czech Republic).-Acta Mus. Siles. Sci. Natur., 67: 193-292, 2018. Abstract: New faunistic data of Psychodidae (Diptera) from Western Bohemia are presented (266 sites explored in 1993-2010, incl. literary data). Altogether 96 species of moth flies (adults) of 36 genera (55 % of all species ... [Show full abstract] of the family known from the Czech Republic are known to occur in the western Hercynian mountains, Sokolov open-cast coal mines, dumps and adjacent localities. 26 of these species were classified in the national Red List 2005 of threatened invertebrates. Critically endangered species CR (14), endangered species EN (4), vulnerable species VU (8) and without a Red status so far are two species nationally scarce NS. An extreme water chemistry of some mine localities (pH, alkalinity, N-NH4 + , N-NO3-, N org., total N, total P, Na, K, Ca, Mg, Fe, Cl-, SO4 2-, Mn and conductivity) in a relation to collected adults were studied. The relationship between site altitude of all localities and the number of species as well as critically endangered species is accounted.