A Taxonomical Revision Of The Aneuraceae Of China

The Aneuraceae belonging to Metzgeriales of Jungermanniopsida is the largest family of thalloid liverworts.Aneuraceae is cosmopolitan and it is one of the main components of bryophyte communities in moist habitats,especially in subtropical and tropical regions.Five genera are currently recognized in Aneuraceae:Afroriccardia,Aneura,Lobatiriccardia,Riccardia and Verdoornia.Of which genus Riccardia(approximately 300 taxa)occupies more that 90%of this family.Since the family was established by Klingger in 1858,the study of species delimitations and infragenetic taxonomy has never been less challenging due to the substantial morphological overlap and high morphological plasticity of closely resembling species.Challenges in taxonomic revision of the Chinese Aneuraceae include small size of the samples,thereby resulting in difficult identification and sample collection as most species occur on moist gulley and cliff,as well as having unable to retain oil bodies in dried materials.Therefore,the revision of Chinese Aneuraceae's taxonomy has an important significance in revealing the byroflora of China and the world.The limitation of taxonomic characters in morphology and the lack of molecular phylogenetic studies made Ricccardia doubtful in species delimitation,molecular phylogeny and relationship among genera.In the last decade,the application of molecular methods to the taxonomy of liverworts has clarified some taxonomic problems.The molecular study substitutes the deficiency of traditional morphological studies to produce a more effective research which has greatly promoted the understanding of different taxa.In the present study,a taxonomical revision of Aneuraceae of China was carried out based on morphological-anatomical and molecular phylogenetic analyses.The morphological-anatomical investigation was based on 800 specimens of the family including 62 specimens of Aneura,8 specimens of Lohatiriccardia and over 700 specimens of Riccardia.A total of 38 specimens in four genera of Aneuraceae were studied using molecular analyses in which the outgroup exhibiting five species of Metzgeria and Pleurozia.Two chloroplast regions(rbcL,trnL-F)and nuclear ribosomal internal transcribed spacers 1 with the intervening 5.8S ribosomal subunit(nrITS)were used for maximum parsimony(MP),maximum likelihood(ML)and Bayesian inference(BI)phylogenetic analyses.The results are as followed:1.The study confirmed 40 taxa(36 species,1 subspecies and 3 varieties)in three genera(Aneura,Lobatiriccardia and Riccardia)of Aneuraceae in China.Most species of Riccardia are distributed in the southern China,particularly tropical and subtropical regions,such as Guangxi Hainan,Taiwan,Yunnan,The highest number of species occurs in Yunnan where 25 species(69.44%)of three genera are known.The second species diversity center is in Hainan where 18 species(50%)of three genera were confirmed.2.Riccardia multifida and R.chamedryfolia stood out by their commonly wide distribution in almost every province.In Riccardia 11 species are newly reported for Yunnan,followed by Hainan(1 subgenus and 9 species),Fujian(1 genus and 7 species),Guangxi(9 species),Xizang(3 species),Sichuan(3 species),Anhui(2 species),Zhejiang(2 species)and Guizhou(1 species).3.In addition,Riccardia hainanensis and R.yunnanensis are new to science.Meanwhile,R.glauca Furuki,R.planiflora,R.vitrea,and R.inconspicua are firstly reported for China whereas R.flavovirens,R.marginata.R.pusilla.and R.pumila are reported for mainland China for the first time.4.The specific rank of Riccardia latifrons var.miyakeana is resurrected based on the molecular and morphological analysis.