Phylogeny of Sciara
Fig. 1 Sciara, the fungus gnat.Sciara (Fig. 1) is among the largest genus in the world, with over 700 species. It falls within the phylogenetic class Insecta that contains 26 orders of extant insects with ~700,000 species, which is three times as many as all other animal species together. Sciara is a Holometabolous insect (Fig. 2), meaning that it undergoes metamorphosis from larva to pupa and adult. It is in the order Diptera (true flies), which is among the largest radiation of terrestrial eukaryotes (Wiegmann et al. 2003) and is one of the most ecologically diverse and species-rich group of insects. Dipteran flies probably arose in the Permian and the main lineages of flies were already present in the Triassic (Yeates and Wiegmann 1999). Many consider there to be two suborders of Diptera: the lower Diptera (long antennae) are the Nematocera and the higher Diptera (short antennae) are the Brachycera. Sciara are lower Diptera whereas Drosophila are higher Diptera, and they diverged from one another around 220-240 MYA. Several papers on dipteran/insect phylogeny have appeared recently (Wiegmann et al. 2011; Trautwein et al. 2012; Misof et al. 2014; Kjer et al. 2015).
Fig. 2. Dipteran Phylogeny. Some key organisms with sequenced genomes shown in blue.
In his revision of the family Sciaridae, Steffan (1966) proposed that Sciara coprophila be reclassified as Bradysia coprophila. To prevent confusion with the older research literature, most scientists who work with this species still call it Sciara coprophila. The Sciaridae are considered by most to be a distinct family, but previously they were treated as a subfamily of the Mycetophilidae (Steffan 1966).
Sciarid flies are found world-wide. Meigen (1803) first recognized sciarids as a distinct taxon. The first comprehensive study of sciarid flies was undertaken by Winnertz (1867) who described European species. Subsequently, Grzegorzek (1885) presented a key to 236 species of Sciara. Wiedemann (1821) described the first two North American sciarids. This classification was expanded by Johannsen (1912) who described 56 species of Sciara in North America. Brunetti (1912) described 58 species of Sciara from Asia, and Tonnoir and Edwards (1927) described 20 species of Sciara from New Zealand. Rhynchosciara is found in South America.