Overview
The family Mycetophilidae traditionally encompassed all the 'fungus gnats', although the concept was restricted subsequently to exclude the Sciaridae. Recently, it has become clear that recognition of the Sciaridae rendered the remaining Mycetophilidae paraphyletic (the Sciaridae is the sister group to only a part of the broader concept). Faced with restoring the monophyly by re-incorporating the Sciaridae into an expanded Mycetophilidae, or elevating the rank of several more subfamilies to give each group monophyly, the latter course generally has been accepted. Thus, the superfamily Mycetophiloidea now comprises the families Ditomyiidae, Diadocidiidae, Keroplatinae, Bolitophilidae, Mycetophilidae (sensu stricto), Lygistorrhinidae and Sciaridae (e.g. Matile 1990). This is the approach adopted here.
Even as restricted, the cosmopolitan family Mycetophilidae remains the most species-rich of the Mycetophiloidea, comprising over 3,000 species in some 150 genera.
Adult Mycetophilidae are quite ubiquitous, particularly in damp, shaded woodlands where there are fungi that provide the dominant larval habitat. The larvae are typically mycetophiloid but appear to lack any defining synapomorphies. Many larvae develop within or beneath fungal fruiting bodies (sporophores) particularly soft Basidiomycetes, whereas others spin webs under bark and a few are predatory.
Description
Mycetophilidae are recognisable in the adult stage by the wing veins M and CuA1 being unconnected (i.e. lacking crossvein bm-cu) and all veins complete from the base to the wing margin. This family contains wingless species.