Taxonomic Revision On Key Taxa Of The Arachniodes Bl.from China

The fern genus Arachniodes Blume is a large genus in Dryopteridaceae.The important classification characteristics that different from other genera of Dryopteridaceae is its rhizomes shape are usually creeping(long or short),ascending or rarely erect.and its most species of lamina are usually 3-4 pinnate,a few species are 2,5 pinnate,and its leaves shape are triangular or pentagonal,and its sori on the veinlets of the ultimate pinnules,indusia brown,entire.This study through specimen collection in the field,specimen inspection and identification,literature research,experimental study and so on to study its rhizome morphology,scale shape,leaf shape,spore ornamentation,the geograghic distribution and to classify and revise the 19 species of Arachniodes Blume,among them,18 species have been observed on its scale,12 species have been scanned and compared its spore powder,5 species have been published.1.RhizomeSo far,there is no data completely recorded its rhizome morphology.This study have compared the rhizome morphology of the 19 species of Arachniodes Bl.based on the field observation,reviewing specimen literature and morphological observation.The results showed that the main rhizome morphology of Arachniodes Bl.are creeping,ascending or rarely erect that can be used as the main characteristics of species classification identification.2.ScaleThe characters of scale of 18 species of Arachniodes Bl.were examined by means of light microscopy.It was shown that 5 shape types:lanceolate,narrow-lanceolate,linear-lanceolate,wide-lanceolate,subulate;and 2 colors:brown,black and some intergradations.Scales on the rhizome and the base of stipe could be used to distinguish some species.3.PalynologyThe spore morphology of 12 species of Arachniodes Bl.were investigated by scanning electron microscopy.The shape of the spores were monolete,bilaterally symmetrical.There are total five ornamentation types,including lophate,lamellate,tuberculate,enestrate,auriculate,and there is a transition type between all kinds of types.The ornamentation of spores is relatively stable that can provide important basis for differentiating the species in Arachniodes Blume.3.Lamina morphologyThe morphological characteristics of Arachniodes Bl.includes lateral vane,apical vane,basal vane,the vane whether have petiole,vane edges and lobes.The leaf top of the most Arachniodes Bl.have apical vane with petiole,and its apex are pinnatifid and acuminate.The apical vane of a few Arachniodes Bl.sharp shrink into caudate or triangle.There are different types of basal vane,such as triangle,pentagon,ovoid or broadly ovoid.And its most species of leaves are usually 3-4 pinnate,a few species are 2-5 pinnate.We can distinguish the similar species according to the above characteristics and combined with the feature of rhizomes and spores ornamentation.4.Taxonomic revisionAll species in Arachniodes Bl.were made classification through verified and researched the specimen and type specimen that stored in herbaria(PYU,PE,KUN),and combined with field collection and observation.As a result,Arachniodes aristata(Forster)Tindale,Arachniodes exilis(Hance)Ching,Arachniodes reducta Y.T.Hsieh et Y.P.Wu,Arachniodes japonica(Sa.Kurata)Nakike?Arachniodes leuconeura Ching are recognized independent species.The key to species,the citing of specimen,the profile introduction of characteristic,photograph of field or specimen,geographical distribution and elevation range of Arachniodes Bl.are provided in this paper.