We provide the first molecular phylogeny of Keroplatidae and Lygistorrhinidae, families of fungus gnats (Diptera: Bibionomorpha: Sciaroidea). Phylogenies reconstructed by Maximum Likelihood and Bayesian methods, based on four nuclear and four mitochondrial gene markers (5106 base pairs) sequenced for 75 genera and 105 species, show Keroplatidae as monophyletic only with the family Lygistorrhinidae included, herewith treated as the subfamily Lygistorrhininae stat. nov. The subfamily Arachnocampinae is retained in the family, although lowering its overall support. An early branching clade, comprising species of Platyura Meigen, 1803 and Paleoplatyura melanderi Fisher, 1941, forms subfamily Platyurinae Loew, 1850 stat. nov. The subfamilies Sciarokeroplatinae and Macrocerinae grouped together with three genera considered here as Keroplatidae incertae sedis. Subfamily Lygistorrhininae forms a sister clade to subfamily Keroplatinae, both retained monophyletic with high support. The traditional division of the subfamily Keroplatinae into the tribes Orfeliini and Keroplatini appears as outdated, resting largely on adaptive characters prone to parallel evolution. We find support for an alternative tribe corresponding to the Cloeophoromyia–Asindulum genus group, but a tribal reclassification of the Keroplatinae is left for future studies. The genus Heteropterna Skuse, 1888 is considered as identical with Ctenoceridion Matile, 1972 syn. nov.

A new species of Keroplatidae (Diptera: Sciaroidea), Macrocera rohaceki sp. nov., is described from the island of Mallorca (Spain). A further remarkable species, Paleoplatyura johnsoni Johannsen, 1910, hitherto only known from the Nearctic Region, is recorded from Sicily (Italy). New records of Isoneuromyia czernyi (Strobl, 1909) and I. pseudochracea (Landrock, 1925) from Slovakia are provided, including figures of the male terminalia. Their relationships to the widely distributed European species, I. semirufa (Meigen, 1818), are reconstructed using three mitochondrial DNA markers (12S, COI, cytb). A key to the European species of Isoneuromyia Brunetti, 1912 is also provided.

New records of Anisopodidae, Bibionidae, Cecidomyiidae, Keroplatidae and Mycetophilidae (Diptera) are presented from Muránska planina National Park (Slovakia) and the Czech Republic. The material was obtained mainly in the years 2009-2015 by means of Malaise traps and individual collecting. Three species are new to the Czech Republic, 1 to Bohemia, 3 to Moravia & Silesia and 10 to Slovakia. Several additional rare species are also recorded although they do not represent additions to the local faunas.