Taxonomic Study On Coniogramme Ser. Fraxineae And Its Allies

Coniogramme Fée,which comprises ca.50 species,which belongs to subfamily Cryptogrammoideae in Pteridaceae.It is a perennial herbaceous fern genus.It is mainly distributed in the tropical and subtropical regions of Asia.Morphologically,C.ser.Fraxineae is characterized by pinnules with entire margins and comprises ca.10 species.Based on specimen inspection and extensive field observation,the author researched 10 species of C.ser.Fraxineae and its allies in the number of sporangium annulus cells,hydathodes,scales,morphological of fronds,spore micromorphology and molecular systematics.The results are summarized as follows:(1)The number of sporangium annulus cells is highly valuable in taxonomic revision in C.ser.Fraxineae based on population sampling.Based on the number of sporangium annulus cells,the species were categorized into three groups: the species with the lowest number of sporangium annulus cells within the range of 10-11;the species with a median number of sporangium annulus cells of13-15;the species have the highest number of sporangium annulus cells,within the range of 16-18.(2)The morphology and placement of hydathodes were found to be continuously varied between populations,thus the morphology of hydathodes should not be overemphasized in delimiting species.(3)The morphology of rhizome scales in C.ser.Fraxineae is consistent,lanceolate,with entire margins and fine meshes.(4)There are three types of pinnate splitting,1-pinnate fronds,2-pinnate fronds and complete2-pinnate fronds.The morphologic variation of the apex of the pinnules is large and has no taxonomic value.Three kinds of indumentum are found in the series: glabrous,short hairs and long hairs.The indumentums type is stable within the series,while density of indumentums is greatly influenced by environment.In addition,different types of indumentums can provide evidence for species division.(5)There is little difference in the morphology of spores which are tetrahedral,have obvious corners,three cracks and radiative symmetry.The superficial ornamentation of spores is irregular granular(wrinkled).(6)Molecular phylogenetic analysis indicated that C.ser.Fraxineae is a paraphyletic group,C.macrophylla(Blume)Hieronymus?C.macrophylla var.coplandi(Christ)Hieronymus and C.merrillii are sisters to the rest species of Coniogramme.Furthermore,phylogenetic reconstruction showed that C.procera is closely related to C.venusta and C.petelotii.(7)Based on macromorphology,micromorphology and molecular systematics,nine species are recognized in C.ser.Fraxienae and its allies.C.lanceolata,C.falcata(Don)Salomon and C.fraxinea(Don)Diels f.connexa are reduced as the synonym of C.fraxinea.C.merrillii and C.macrophylla var.copelandi are reduced as the synonym of C.macrophylla.C.javanica are resurrected.