The adult morphology of Mycetophilidae (s.str.), with a tentative phylogeny of the family (Diptera, Sciaroidea)

The external, adult morphology of the Mycetophilidae is outlined. Thirty-nine genera representing all commonly recognised subfamilies and tribes have been studied, with emphasise on genera not included in the two tribes Mycetophilini and Exechiini. Characters supposed to be of systematical importance are emphasised, and such characters have, above all, been found in the structure of the head, mouth parts, thoracic sclerites and in the highly complex genital apparatus in male and females. A secondary fission of the gonocoxites apparently has taken place in several genera, in both sexes. The survey reveals the 10th abdominal segment to be mon: important in the composite structure of the male terminalia than recognised by most authors. Derivatives of this segment may be traced as lobes posteriorly of the epandrium, or possibly as accompanying appendages of the gonostylus. In females the presence of a pair of gonocoxites and a pair of gonapophyses on each of the 8th and 9th abdominal segments, together with a well. developed sternite 10 is demonstrated A tentative phylogenetic analysis based on the studied genera is presented. The analysis strongly rejects the common practice of ranking Edwards' (1925) tribes as subfamilies. Neither, does it support the maintenance of the three commonly recognised subfamilies. Pending further studies it is recommended to treat the entire group as one family, and retain a modified tribal classification.