An evolutional special case in the lower Orthorrhapha: some attractive fossil flies from the Middle Jurassic of China (Insecta: Diptera: Brachycera)

摘要

More than ten extinct Lower Brachycera families have been discovered throughout the world. These fossil records are of great significance in piecing together jigsaw puzzles of evolution for the Order Diptera. However, the distinct systematic relationships of the Diptera, one of the four largest orders, remain obscure. Herein, we erect a new family to enhance our systematic understanding of the Diptera. The Uranorhagionidae fam. nov. is a bewildering new extinct family comprising two new genera, Uranorhagio gen. nov. and Strenorhagio gen. nov., and five new species, Uranorhagio daohugouensis sp. nov., Strenorhagio deviatus sp. nov., Strenorhagio grimaldi sp. nov., Strenorhagio asymmetricus sp. nov., and Strenorhagio conjugovenius sp. nov., from the Middle Jurassic of China. Members of the new family are moderate to large in size and robust in shape. This family possesses a peculiar shape of vein R2+3, the basal part of which is strongly fornical and nearly geniculate, and has the crossvein r-m at variable position. Furthermore, the Uranorhagionidae fam. nov. exhibits a mixture of distinct characters of two families in two disparate superfamilies, i.e. Rhagionemestriidae (Nemestrinoidea) and Rhagionidae (Tabanoidea), thus suggesting that this family might be in an inclusive position in dipteran phylogeny. We tentatively place this new family as a member of Tabanoidea, pending the discovery of more fossil specimens and further study. The comparison between the new family and other relative families will be discussed.