Phylogeny of the Sciaroidea (Diptera) as estimated from 16S and 12S ribosomal RNA sequences

The phylogeny of the superfamily Sciaroidea (Diptera) is estimated from 16S and 12S ribosomal RNA sequences in a series of analyses using various combinations of the sequence data. A historical overview of the classification and phylogeny of the taxon is provided and current hypotheses are discussed. Alignment of the 12S sequences was achieved by constructing models for the secondary structure of the RNA molecule. These models are included in the appendix.; Previous analyses of the Sciaroidea have assumed the Bibionidae to be the taxon's sister group. This assumption was tested by initial analyses in which the non-bibionomorph families Tipulidae, Culicidae, Simuliidae, Anisopodidae, Ragionidae, Empididae, Drosophilidae, and Calliphoridae were included. In these analyses the Bibionidae consistently emerged on the same clade as the sciaroid taxa and in the majority of cases formed the sister group of the Sciaroidea.; A second group of analyses based on the 12S data used the Bibionidae as the outgroup for an investigation of the relationships within the Sciaroidea. The Cecidomyiidae and Ditomyiidae emerge as the basal-most members of the superfamily with the Cecidomyiidae as the sister group of the remaining sciaroid taxa (the fungus-gnat families). The Sciaridae branch next from the main stem of the phylogeny just above the Ditomyiidae, followed in order of sequence by the Keroplatidae, Diadocidiidae, Bolitophilidae, and Mycetophilidae ( sensu stricto).; A third set of analyses using only 12S RNA sequences investigated the phylogenetic relationships within the Mycetophilidae using the Bolitophilidse as the outgroup. The Mycetophilidae has a three-clade structure with one clade consisting of the subfamily Mycetophilidae which further splits into two clades corresponding to the tribes Exechiini and Mycetophilini of present classifications. The Mycomyinae and Sciophilinae emerge together on a common clade, and the third clade includes taxa presently classified in the Gnoristinae and Leiini. The gnoristine-leiine clade splits into three subclades, one of which includes Coelosia, Hadroneura, Synapha (all Gnoristinae) and Leia (Leiinae); a second subclade consists of Gnoriste and Boletina (Gnoristinae) and Docosia (Leiinae): finally Tetragoneura and Acompterella, both genera presently included in the Leiinae, occupy a third subclade.