Systematic Taxonomy Studies On Ophiorrhiza Japonica,Ophiorrhiza Cantoniensis And Their Related Taxa

Ophiorrhiza(Rubiaceae)comprises approximately 70 Ophiorrhiza species in China.Among them,O.japonica and O.cantoniensis have widest distribution.At present,for the two species and their related taxa,some taxonomic and systematics problems are still not well resolved.This work aimed to clarify taxonomic confusion and reconstruct phylogenetic relationship between 12 species of Ophiorrhiza by three methods,including statistical analysis of 22 quantitative traits,comparative study of leaf epidermis and seed micromorphology and analysis sequence variation information of ribosomal gene ITS and chloroplast DNA atpB-rbcL.Result is following:1.Quantitative taxonomic analysis:(1)leaves,bracts,corolla and calyx were the key traits to distinguish these related taxa.O.japonica and O.cantoniensis could be distinguished by bracts and calyx,but it was difficult to distinguish them from their four relative taxa respectively.(2)O.nigricans is significantly different from other groups in leaves,calyx,sepals and corolla traits.(3)O.paniculiformis has a large difference in leaf growth,bracts and inflorescence growth patterns from other groups.2.The comparative study of micromorphology have some certain reference value.Leave surface comparison showed that stoma morphology,density and size of leaf epidermis can be used to identified several species.Seeds surface comparison showed that shape of leaf epidermal cells,the vertical wall pattern and the convex pattern and distribution characteristics of seed epidermal cells have classification value.The shape of leaf epidermal cells of O.longipie and O.chingii,and the pattern of seed surface protrusion of O.paniculiformis were different from other groups.3.Molecular phylogenetic studies:(1)O.cantonensis and its related groups,O.filibracteolata,O purpureonervis and O.salicifolia,formed a branch with high statistical support rate.(2)O.japonica and its related groups,O.laoshanica,O.lignose and O.petrophila constitute a branch with high statistical support rate,and the latter three intersperse and nest in O.japonica.(3)The developmental trees showed that O.nigricans and O.paniculiformis were in different branches with O.japonica and O.cantonensis respectively,which did not support the previous synonyms treatment of O.nigricans as O.japonica and O.paniculiformis as of O.cantonensis4.Based on all results,it can be supported that:(1)O.laoshanica,O.lignosa and O.petrophila probably were synonyms of O.japonica;(2)O.salicifolia,O.filibracteolata and O.purpureonervis were probably synonymous with O.cantoniensis;(3)taxonomy status of O.nigricans and O.paniculiformis does not reach the significant level.;(4)two newly species,Ophiorrhiza revolutus and Ophiorrhiza goui,were discovered.Moreover,the relationship between O.longipie and O.chingii and other groups needs to be further study.