An integrative taxonomic treatment of the Mycetophilidae (Diptera: Bibionomorpha) from Singapore reveals 115 new species on 730km 2

Abstract “Open ended” or “dark taxa” are species-rich clades that are so abundant and diverse that conventional taxonomic methods tend to struggle with the onslaught of specimens and species. New approaches based on presorting specimens to putative species with low-cost DNA barcodes may make tackling these taxa manageable. However, this will still require limiting the geographic scope of taxonomic revisions, given that most countries and biogeographic regions will have too many specimens and species for comprehensive coverage. We demonstrate the power of this approach by carrying out a revision of the Mycetophilidae fungus gnats (Diptera) of Singapore. The material revised here was obtained from 496 samples collected with 71 Malaise traps placed at 107 sites in different habitats in Singapore: mangroves, swamp forests, freshwater swamps, primary rainforests, and different types of secondary forests (old, maturing, young, urban). Based on molecular and morphological data for 1,454 specimens, we delimit 120 species of 23 genera. Of these, only five were species previously described. The remaining 115 species are new to science and described here. We name, however, only 98 of these species since 14 species are currently only known from females and we cannot prepare a fully satisfying morphological diagnosis ( Manota spp. A–G and Neoempheria spp. A–G), and three species lack molecular data ( Epicypta sp. A, Epicypta sp. B, and Neoempheria sp. H). To assess congruence between species delimited with DNA barcodes (3% clusters) and morphology, we determined a match ratio and found it to be overall high (95%) with even higher match ratios (99%) observed for MOTUs clustered at 5% with Objective Clustering and MOTUs obtained with ABGD set to (P=0.060). Overall, the ratio of undescribed to described is an astonishing 20:1. Only revising the Singapore fauna increases the number of described species of Oriental Mycetophilidae by about 25%, highlighting the size of the taxonomic impediment for fungus gnats. Most of the Singapore Mycetophilidae diversity belongs to three genera— Neoempheria Osten-Sacken (31 species), Epicypta Winnertz (29 species) and Manota Williston (14 species), but we also describe a new genus— Integricypta , gen. n. , which is the putative sistergroup of Aspidionia Colless—belonging to the Mycetophilinae Mycetophilini based on three species. The species sequenced, illustrated, and named are: Leptomorphus rafflesi , sp. n. ; Monoclona simhapura , sp. n. ; Azana demeijeri , sp. n. ; Azana leekongchiani , sp. n. ( Sciophilinae ); Tetragoneura crawfurdi , sp. n. ; Tetragoneura chola , sp. n. ; Tetragoneura dayuan , sp. n. ; Tetragoneura farquhari , sp. n. ; Ectrepesthoneura johor , sp. n. ( Tetragoneurinae ); Mohelia zubirsaidi , sp. n. ; Allactoneura tumasik , sp. n. ; Allactoneura limbosengi , sp. n. ; Manota banzu , sp. n. ; Manota tantocksengi , sp. n. ; Manota bukittimah , sp. n. ; Manota chiamassie , sp. n. ; Manota danmaxi , sp. n. ; Manota mahuan , sp. n. ; Manota temenggong , sp. n. ; Clastobasis sritribuana , sp. n. ; Clastobasis bugis , sp. n. ; Clastobasis oranglaut , sp. n. ( Leiinae ); Parempheriella mait , sp. n. ; Parempheriella longyamen , sp. n. ; Parempheriella peranakan , sp. n. ; Mycomya sachmatich , sp. n. ; Neoempheria merlio , sp. n. ; Neoempheria sabana , sp. n. ; Neoempheria sangabo , sp. n. ; Neoempheria shicheng , sp. n. ; Neoempheria ujong , sp. n. ; Neoempheria subaraji , sp. n. ; Neoempheria kokoiyeeae , sp. n. ; Neoempheria mandai , sp. n. ; Neoempheria malacca , sp. n. ; Neoempheria sinkapho , sp. n. ; Neoempheria singapura , sp. n. ; Neoempheria xinjiapo , sp. n. ; Neoempheria puluochung , sp. n. ; Neoempheria merdeka , sp. n. ; Neoempheria neesoon , sp. n. ; Neoempheria pulau , sp. n. ; Neoempheria cinkappur ,