The Mesozoic Family Eremochaetidae (Diptera: Brachycera) in Burmese Amber and Relationships of Archisargoidea: Brachycera in Cretaceous Amber, Part VIII

All 16 species of the family Eremochaetidae occur from the Late Jurassic to the mid-Cretaceous of eastern and Central Asia. The first species in amber, and the latest occurrence of the family, was recently described as Zhenia xiai, from the mid-Cretaceous of Myanmar, ca. 100 Ma. New observations of a finely preserved specimen allow refinement of the morphological interpretations in the original description. The female of Zhenia, for example, has the distinctive piercing oviscapt of the superfamily Archisargoidea, formed from modified cerci (not tergites 8 and 9 as originally reported). The pretarsus of Zhenia bears an enormous empodial pad and pair of pulvillae, but the claws are highly vestigial (contra Zhang et al., 2016). The fly was almost certainly a parasitoid. A cladistic analysis of 26 binary-state characters and six continuously variable characters, using 47 exemplar Archisargoidea species from most genera and all four families, and five outgroup Brachycera, has very poor support for most clades but confirms the position of Zhenia in Eremochaetidae. Evidence on the relationships of Archisargoidea to other Brachycera is reviewed, and a close relationship to the Nemestrinoidea or Muscomorpha is best supported. A catalog of the species and some higher taxa of Archisargoidea is provided.