A comparative SEM study of the eggs of the Sepsidae (Diptera) with a cladistic analysis based on egg, larval and adult characters

Abstract

AbstractThe eggs of 21 species in 12 genera of Sepsidae were studied using scanning electron microscopy. All but the eggs of Ortalischema have respiratory filaments which aid in gas exchange. Judged by positional differences and the lack of a central canal, the two filaments of Orygma are not homologous to the single filament of most remaining sepsids. Hinton's hypothesis that egg filaments are plesiomorphic for the Sepsidae is therefore rejected. Three egg characters are added to an existing data set comprising 58 taxa and 85 larval and adult characters. The egg characters allow the unambiguous placement of Lasionemopoda, for which the larval and adult data set had suggested two different positions on equally parsimonious trees. Based on the position of Lasionemopoda, the evolution of the fore femora of the Sepsidae is briefly discussed. The egg morphology of the Sepsidae is also compared to the morphology of drosophiline eggs which also have egg filaments.