On the egg morphology and phylogenetic relationships of Diopsidae (Diptera: Schizophora)

Abstract

The egg morphology of 28 species of Diopsidae is described based on scanning electron microscopy and semi-thin sections for selected species from the following genera: Chaetodiopsis, Cyrtodiopsis, Diasemopsis, Diopsis, Eurydiopsis, Teleopsis, Teloglabrus, Trichodiopsis. Generic descriptions and a key to genera based on egg characters is presented. A data set for phylogenetic analysis is assembled and subjected to the first morphology-based numerical cladistic analysis for the family. The data set consists of 44 adult characters taken from the Diopsidae literature and 10 new egg characters. Cladistic analysis confirms the traditional concept of the family Diopsidae composed of the Centrioncinae (lacking eye stalks) and Diopsinae (with eye stalks) and the Syringogastridae are likely to be the sister group of Diopsidae. Within the Diopsinae, the genus Sphyracephala (including Pseudodiopsis) with its relatively short eye stalks is monophyletic and the sister group of the remaining Diopsinae. The following higher-level phylogenetic hypothesis is proposed (Centrioncinae (Sphyracephala ((Diasemopsis, Trichodiopsis, Chaetodiopsis) ((Teleopsis, Cyrtodiopsis) (Eurydiopsis, Diopsis))))). A high degree of congruence is observed for the morphological data and a recently assembled molecular data set. It is once more confirmed that egg characters provide valuable information for cladistic analysis and identification purposes.