Fungus Gnats (Diptera: , Mycetophilidae, Mycetophilinae)

This Royal Entomological Society Handbook to British Insects covers the subfamily Mycetophilinae of the family Mycetophilidae, commonly known as the fungus gnats. Most 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. They may be found throughout the year, their relative abundance affected by prevailing weather conditions and the consequent effect on the availability of fungus hosts.

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, 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.

Fungus gnats belong to the large group of two-winged flies that comprise the Lower Diptera (often known as Nematocera). This group shares a range of primitive characters, of which the most obvious is their more or less elongate multi-segmented antennae. It includes the craneflies and mosquitoes, as well as several families that are variously termed as gnats and midges. While many other Lower Diptera are aquatic as larvae, fungus gnats belong among those families that are terrestrial in their developmental stages. They include species developing in rotten wood, in bryophytes and in bird’s nests, but the majority are mycophagous (= fungivorous) and develop in fungi.

Handbooks for the Identification of British Insects is a series of books produced by the Royal Entomological Society (RES). The Handbooks provide identification keys to the insects of Britain, along with concise morphological, biological and distributional information. All books contain line drawings. The most recent also feature colour photographs. RES Handbooks are suitable for experienced users. Many out-of-print Handbooks are now available for free download from the RES.