A Systematic Study On The Plagiogyria Mett.

Plagiogyria Mett.is the only genus in the family Plagiogyriaceae,Southwest China is considered its geographical distribution center.This study made full use of specimens and spores from the Herbarium of Pteridophyta Yunnan University(PYU)and specimens collected in the field,the phylogenetic relationships of Plagiogyria and the relationships between the various species were discussed based on the evidence from morphology,palynology and molecular phylogeny.The main findings are as follows:1.morphologyShape of stipe above can be divided into three types: Tetragonal,triangular and cylindrical.Adnate location of sterile pinnae can be divided into three types: base and above,middle and above,apex.The number of pinnae varies greatly among different species,some have more than 40 pairs,while others are only about 10 pairs.The shape of sterile frond's apex can be divided into four types(with pinnatilobed segment,with triangular segment,Plagiogyria japonica,P.euphlebia).Indumentum on stipe and rachis is an important characteristics of Plagiogyria maxima and Plagiogyria lanuginose.2.PalynologySpores of 27 species(including varieties)of Plagiogyria were observed under scanning electron microscopy(SEM).The spores of Plagiogyria are tetrahedral and radially symmetrical.Triangular in polar view,hemispherical or subhemispherical in equatorial view.Trilete,the laesura is almost as long as the equatorial axis.Spores with perispore.The spore size is about 16.42~42.89(25.83)× 26.28~61.33(39.81)?m.Length of laesura is(14.37-29.87)?m,thickness of leasura is(0.74-3.55)?m.The spore ornamentation can be divided into three types: tuberculate,verrucate and rodlets.3.Molecular phylogenyBased on the phylogenetic tree constructed by 6 cpDNA sequences(atpA,atpB,rbcL,rps4,psbA and trnL-F),the topological structure of the phylogenetic tree obtained by the two methods of maximum parsimony method(ML)and Bayesian method(BI)was consistent.All the materials of the genus Plagiogyria used in this study constitute a monophyletic group.The phylogenetic tree can be divided into 6 main branches: Clade A-Clade F.Among them,Clade A(Including Plagiogyria matsumureana and P.pectinate)is the earliest differentiated branch,which is the basal group of the genus Plagiogyria.4.Ancestral character reconstructionThe results of ancestral character reconstruction showed that the recent common ancestor's main spore ornamentation is tuberculate and granular is a symplesiomorphy of Plagiogyria and outgroups.Adnate location of sterile pinnae is base and above,shape of stipe above is tetragonal,the number of pinnae can exceed 40 pairs and apex of lamina pinnatifid are the ancestral state,the remaining characters are derived characters.5.Taxonomic treatmentIn this study,Plagiogyria matsumureana Makino,P.pectinata(Liebmann)Lellinger,P.dunnii Cop.,P.assurgens Christ,P.taliensis Ching,P.virescens(C.Chr.)Ching,P.stenoptera(Hance)Diels,P.maxima C.Chr.,P.koidzumii Tagawa,P.japonica Nakai,P.angustipinna Ching,P.hainanensis Ching are recognized independent species;P.sp.(Voucher: ZXM1267;ZL3169)is considered a new species.We support the merging treatment of P.glaucescens Ching and P.media Ching into P.glauca(Blume)Mett.,the merging treatment of P.euphlebia(Kunze)Mett.and P.grandis Cop.into P.euphlebia(Kunze)Mett.,the merging treatment of P.adnata(Bl.)Bedd.,P.distinctissima Ching and P.yunnanensis Ching into P.adnata(Blume)Bedd..The taxonomic status of other species involved in this study remains to be studied.