Systematics and evolution of the basal lineages of Therevidae (Insecta: Diptera)

The objective of this study was to resolve the relationships among the basal lineages of the family Therevidae (Insecta: Diptera) and to test the monophyly of the family and the two basal subfamilies. A chapter on the morphological features of Phycinae and Xestomyzinae was produced to unify the terms used in this study. A world catalog of Phycinae and Xestomyzinae is provided, which include the names of all described species belonging to these two subfamilies. Keys to the genera of Phycinae and Xestomyzinae are given, together with a diagnosis and distribution map of each genus. Four new species of Xestomyzinae are described from Madagascar. One new genus of Xestomyzinae and three new species from sub-Saharan Africa are described as new to science. All fossil taxa described as Therevidae were examined and revised. From the four fossil species from Florissant, Colorado, only one species belongs to the family Therevidae; from Mexican amber a new genus and species of Xestomyzinae is described; and the Baltic amber fauna consisted of three monotypic Phycinae genera and one monotypic Xestomyzinae genus, of which three genera and one species are described as new. For the phylogenetic study 67 ingroup taxa (Phycinae & Xestomyzinae) and 8 outgroup taxa were scored for 124 morphological characters and 12 of 14 Phycinae genera, as well as 6 of the 10 Xestomyzinae genera were sequenced for the nuclear genes 28S and EF-1alpha. The morphological and the molecular datasets were analyzed both in combination and separately using maximum parsimony and a Bayesian approach to phylogenetic reconstruction. The resulting trees show great congruence in the basal splits but differed in some details in the tip portion of the tree. The results support the monophyly of the family Therevidae, and the subfamilies Phycinae and Xestomyzinae respectively. The subfamily Phycinae is the sister-group to the remaining Therevidae and does not form a monophyletic clade with the Xestomyzinae as hypothesized before. The Xestomyzinae is the sister-group to the remaining Therevidae (with the exclusion of the Phycinae). A divergence time estimate suggested that the basal radiation of the Therevidae was during the time of the Gondwana breakup.