Study On Permineralized Noeggerathialean Leaves From The Xuanwei Formation Of Late Permian Of Fuvuan,Yunnan

Noeggerathiales is an extinct plant group,which fossils are distributed in the early Carboniferous to Triassic strata in Europe,North America,and East Asia and flourished from the Late Carboniferous to the Early Permian.It is also an important component in the Euramerica and Catheysia flora during the periods.Its taxonomical position had remained uncertain for long times.In this paper,a detailed study was conducted on three fossils from the Xuanwei Formation of the Late Permian in Qingyun Coal Mine,Fuyuan County,Yunnan,which preserved both the morphological features and anatomical structures.By the comparing and the discussion,two new species was established:Paratingia qingyunensis sp.nov.and Paratingia fuyuanensis sp.nov.The evolutionary relationship was preliminary raised in the paper.P.qingyunensis sp.nov.was preserved a length of the compound leaf.Pinnules anisophyllous,arranged in four rows,margin entire,radial veins.Dorsal pinnules are larger,elliptic,ratio of long and length 3.3.The epidermal structure was preserved partly on a pinnule,epidermal cells are rectangular or longitudinally polygonal in shape.Stomata oval and no specialized subsidiary cells,random distributed.trichomes are densely attached on the rachis and have rib-liked bulge on the abaxial surface of the dorsal pinnules.Ventral pinnules are smaller,alternative.The rachis preserved the structure of the epidermis,fundamental tissues,vascular bundles and vascular bundle sheaths,the epidermis has undulated and no trichome were obsearved.The vascular bundle consists of a continuous inverted ?-shaped xylem strand and phloem is not preserved.The two specimens of P.fuyuanensis sp.nov.were both preserved a length of the compound leaf.Pinnules dimorphic,arranged in four rows,margin entire,radial veins.Dorsal pinnules larger,elliptic,ratio of long and length 2–2.4.Ventral pinnules are smaller,alternative.Costate tuber were observed on the abaxial surface of both two types of pinnules obviously on cross sections.The rachis preserved the fundamental tissues,vascular bundles and vascular bundle sheaths,the vascular bundle consists of a continuous inverted ?-shaped xylem strand and phloem is not preserved.Trichomes were density attached on the surface of rachis and abaxial surface of the dorsal pinnules.This is the first record of Paratingia in South China,which is the typical genus of Permian Cathaysia flora in the North China,is the latest record of the genus and expanded the time and geographical distribution of the genus.The discovery of new species reflect the consistency between the flora of North China and South China.The paper tried to discuss the evolution relationship of the new species with the other related genera of Noeggerathiales,by comparing the epidermal structure of P.qingyunensis sp.nov.with the previous studies on the epidermal structure of Noeggerathia foliosa and Tingia carbonica,combined with the comparison of geography and geological periods,we preliminarily believe that these three genera may follow Noeggerathia? Tingia?Paratingia evolution sequence.Noeggerathia is the basal lineage and Paratingia is the more derived genus.