Molecular Phylogeny Of Lejeunea (Lejeuneaceae)

Lejeunea Lib., the type genus of the family Lejeuneaceae, has a long history of almost200years. According to literature published in1999, up to1749species had been described under the genus. Although most species were transferred to other genera of Lejeuneaceae or treated as synonyms, about400accepted names in Lejeunea are still accepted now. In the past15years,16genera were reduced to synonyms of Lejeunea. This leads to more species included in the genus, and much morphological variation occurs in the genus. As a result, the distinction between Lejeunea and its allies is blurred. Owing to small plant size, abundant species diversity, and great morphological plasticity of the plants, especially the lack of worldwide taxonomic treatments, species identification, generic definition and infrageneric classification are considered to be very difficult. In the last decade, the application of molecular methods to the taxonomy of liverworts has clarified some taxonomic problems in several large genera (e.g. Scapania, Porella, Frullanid) well, compensated for the deficiency of morphological study and promoted our knowledge about these genera.Phylogentic analysis has been preformed based on the ingroups of142accessions from Lejeunea, Harpalejeunea, Metalejeunea, Microlejeunea, Pluvianthus and Taxilejeunea, and five accessions of outgroups from Cheilolejeunea and Rectolejeunea. The phylogenetic relationship between Lejeunea and its allies was reconstructed based on the combined dataset from chloroplast trnL-F, trnG and nuclear ITS with maximum parsimony (MP), maximum likelihood analysis (ML) and Bayesian inference (BI). In order to reveal the systematic position of some species,62accessions belonging to22genera were selected, some of which came from Genbank data. Two chloroplast genes (rbcL and trnL-F) and one nuclear gene ITS were chosen for the phylogenetic reconstruction of Lejeuneoideae. According to both morphological characters and molecular evidence, the main conclusions are as follows:1.The tranditional Lejeunea is a polyphyletic group. Except for the species with ocelli(Lejunea wallichiana, L. moniliata, L. huctumalcensis), Microlejeunea placed previously in Lejeunea and L. minutilibula, the remains of Lejeunea form a monophyletic clade with strong support (MPBS=98, MLBS=100, BIPP=1). Based on our knowledge on the morphology of Lejeunea and the present molecular data, the new Lejeunea is proved to be a group in which ocelli are absent in leaf lobes. Therefore the species with ocelli in traditional Lejeunea should be excluded from the new Lejeunea. The type of oil body (homogeneous type or compound type) and androecia with bracteoles throughout (or present only at based) are the major morphological characteristics of the new Lejeunea.2. The traditional Harpalejeunea is polyphyletic. The species with diverging underleaf lobes group together and form a monophyletic clade with maximum support from MP, ML and BI. Harpalejeunea filicuspis with narrow underleaf lobes should be transferred to Microlejeunea.3. The present molecular evidence and the morphological characters clarified that Microlejeunea is a separated genus. A wider genus concept of Microlejeunea is suggested here.According to morphological similarity and molecular evidence, monospecific genus Pluvianthus endemic to the Neotropic is reduced to synonymy of Microlejeunea. Pluvianthus squarrosa is transferred to Microlejeunea. The species with ocelli in Lejeunea (L. wallichiana, L. moniliata, L. indica) are moved to Microlejeuea.4. Harpalejeunea, Microlejeunea and Lejeunea comprise a new Lejeunea complex. Harpalejeunea is the base clade of this complex, sister to the other two genera. The characters of the complex match those of the tribe Lejeuneae. So the tribe Harpalejeuneae based on the type genus Harpalejeunea is reduced to the tribe Lejeuneae. According to present molecular data, Metalejeunea with pycnolejeuneoid leaf sequence of gynoecial innovation, previously placed in Lejeuneae is excluded from Lejeuneae. The members of new tribe Lejeuneae are distinguished by the underleaf, ocelli in the leaf lobes and the keel of female bract.5. Analyses based on present molecular data and morphological characters supported that Lejeunea minutilobula is moved back to Cheilolejeunea.6. Because of the distinct morphological differences and the support from the present phylogenetic study, Lejeunea huctumalcensis is separated from Physantholejeunea portoricensis as an independent group, therefore, the genus Otigoniolejeunea should be resurrected.7. According to the nomenclature,3new synonyms and6new combinations are proposed.Lejeuneae R.M.Schust., J. Hattori Bot. Lab.91:148.2001.=Harpalejeuneae R.M.Schust., J. Hattori Bot. Lab.91:156.2001; syn. nov.A/icrolejeunea Steph., Hedwigia27:61.1888.=Pluvianthus R.M. Schust.&Schaf.-Verw. in Schuster, J. Hattori Bot. Lab.75:213.1994; syn. nov.Cheilolejeunea minutilobula Amakawa, J. Jap. Bot.35:365.1960.=Lejeunea minutilobula(Amakawa) X.L.He, Acta Bot. Fenn.163:59.1999; syn. nov. Aficrolejeunea saua/rosa (Steph.) Y.M.Wei&R.L.Zhu, comb. nov. Microlejeunea inaVca (Udar&U.S.Awasthi) Y.M.Wei&RX.Zhu, comb. nov. Microlejeunea moniliata(Mizut.) Y.M.Wei&R.L.Zhu, comb. nov. Microlejeunea wallichiana (Lehm.) Y.M.Wei&R.L.Zhu, comb. nov. Microlejeunea filicupsis(Steph.) Y.M.Wei&R.L.Zhu, comb. nov. Otigoniolejeunea huctumalcensis (Lindenb.&Gottsche) Y.M.Wei, R.L.Zhu&Gradst., comb. nov.