Handbooks for the identification of British insects: Fungus gnats (Diptera Mycetophilidae Mycetophilinae)

Description

This handbook covers the British species of the subfamily Mycetophilinae of family Mycetophilidae, commonly known as the fungus gnats. Most fungus gnats are found in forests and other wooded habitats, as might be expected since the larval development of many species is dependent on saproxylic or mycorrhizal fungi. Fungus gnats may be found throughout the year, their relative abundance affected by prevailing weather conditions and the consequent effect on the availability of fungus hosts. While there is a range of larval habitats among fungus gnats as a whole, members of subfamily Mycetophilinae appear to be exclusively mycophagous; about half the British species of this subfamily have been reared and a systematic list of the known fungus hosts is provided. In the British fauna, fungus gnats comprise 574 species in five families: Bolitophilidae, Diadocidiidae, Ditomyiidae, Keroplatidae and Mycetophilidae, with the majority (501 species) in Mycetophilidae. How to recognise fungus gnats from other Diptera and how to distinguish these five families are described. An earlier handbook (Hutson et al. 1980) covered all except the largest subfamily Mycetophilinae, which is treated here. Keys are provided to the subfamilies of Mycetophilidae and to the 27 genera and 334 species in the British fauna of subfamily Mycetophilinae. Recognition of species depends on the complex structure of their male genitalia, which are illustrated by photographs for all species. Females are not identifiable in some genera; where there are characters that enable them to be identified, this is indicated. Three species are newly added to the British list: Brevicornu canadense Zaitzev, 1988 (previously recorded as an unnamed species near B. arcticum), Trichonta subterminalis Zaitzev & Menzel, 1996 and an unnamed species of Cordyla, while the British Isles species previously identified as Brevicornu arcticum (Lundström, 1913) is now considered to be an undescribed species. These unnamed species are due to be formally described by other authors.