Taxonomy Of Fossil Ephemeroptera From Late Mesozoic In China, With Comments On Succession Of Aquatic Insect Community

Eastern Inner Mongolia and Western Liaoning are located in the northeast part of China. Its non-marine sedimentary strata, especially in Jiulongshan Formation of Middle Jurassic and Yixian Formation of Early Cretaceous, yield a mass of notable fossils including abounded insects which providing important evidence for study of the origin and early evolution of insects.In present dissertation, the geological age of the strata fossil Ephemeroptera of Northeast China and same representative geological sections are introduced. A brief history and actuality of the research on fossil Ephemeroptera, geological history and paleoecology of it are given. The morphology and phylogenetic study of mayfly are reviewed. A comprehensive taxonomic work on fossil mayflies from western Liaoning, eastern Inner Mongolia and north Hebei is presented. 4 families 11 genera and 14 species are reported, including 5 new genera,2 new record genera (Siberiogenites and Foliomimus) and 14 new species. The family Siphlonuridae s. l. includes 2 new genua and 3 new species (Multramificans ovalis gen. et sp. nov.; Jurassonurus amoenus gen. et sp. nov.; Mogzonurella bellatulus sp. nov.). Hexagenitidae includes 1 new genua and 3 new species (Epicharmeropsis hexavenulosus gen. et sp. nov.; Epicharmeropsis quadrivenulosus sp. nov.; Siberiogenites branchicillus sp.nov.). Mesonetidae includes 5 new species (Mesoneta bracteiformis sp. nov.; Furvoneta viriosus sp. nov.; Furvoneta raucus sp. nov.; Clavineta excavatus sp. nov.; Clavineta brevinodia sp. nov.). Epeoromimidae includes 1 new species- Foliomimus latus sp. nov. Furthermore, there are 2 new genera and 2 new species that their station are uncertain at the family level, namely Primigeuus muticus gen. et sp. nov. and Eurythoracalis mirabilis gen. et sp. nov. In addition, 3 new genera and 4 new species (Multramificans ovalis Huang, Liu & Sinitshenkova, 2007; Jurassonurus Huang, Ren & Sinitshenkova , 2008; Epicharmeropsis hexavenulosus Huang, Ren & Shih, 2007; Epicharmeropsis quadrivenulosus Huang, Sinitshenkova & Ren, 2007) ) have been published. The diagnosis of genus Mogzonurella and genus Furvoneta is emended. Epeoromimidae is first recorded from China.Based on the publications reported, aquatic insects with associated animals and plants from Jiulongshan Formation and Yixian Formation are enumerated. According to their biological and ecological characteristics, hypothetical structure and energy flow of aquatic ecosystem on the above two strata are elementarily established, and their environmental settings are reconstructed. By comparison, the climate of the two regions at the time of disposition was all warm and humid, while there was seasonal arid and semi-arid climate in some small places; there were lentic lakes and swamps, in the vicinity of which there were alpines and mountain streams. They are difference as followed. In Jiulongshan Formation, species diversity of aquatic insects was high; aquatic ecosystem was relatively unstable and it may be in the early stage of this community; there were in a small and shallow water environment. While in Yixian Formation, species diversity of aquatic insects was relatively low; food web was intricacy, aquatic ecosystem was comparatively stable and mature; water area was large and deep.The conchostracan Eosestheria, nymphal mayfly"Ephemeropsis"and fish Lycoptera are three typical representatives of Jehol Biota. However, after we studied about one hundred fossil mayfly specimens from Yixian Formation of the Jehol Biota, we believe previously-described specimens from the Yixian Formation, the so-called Ephemeropsis trisetalis, were put into error place of taxonomy and should be transferred into the new genus Epicharmeropsis. In addition, the definition, stratigraphic correlation, geographical distribution of the Jehol Biota and river system during Late Mesozoic are discussed.All the type specimens of the new species are preserved at the Key Laboratory of Insect Evolution & Environment Change, Capital Normal University in Beijing, China.