A Taxonomic Revision Of Smilacaceae In Asia And Phylogeography Of North American Herbaceous Smilax

Smilacaceae is a monocot family with a cosmopolitan distribution, and it is quite difficult taxonomically. Asia is the diversity center of Smilacaceae, with about3/5of the total species and many kinds of morphological variations. But a comprehensive monograph of Asian Smilacaceae has never been published. Based on well-resolved molecular phylogeny, comprehensive literatures and specimens, and extensive fieldworks, here I present a new taxonomic system of Smilacaceae and give a revision for Asian species. A comprehensive study is conducted on the morphology, cytology and molecular phylogeny of a special Smilax population from Yunnan to discuss its systematic position and status. By combining AFLP data and three cpDNA loci, we generate a phylogenetic analysis of herbaceous Smilax species in North America, and use a phylogeographical approach to elucidate the refugial and recolonization history of the eastern North American herbaceous Smilax. The main results are as follows:1. A taxonomic revision of Smilacaceae in AsiaA new taxonomic system for Smilacaceae is proposed, which recognizes one genus, four subgenus and20sections. The genus Heterosmilax is reduced to be a section in the only genus Smilax. In total,124species are recorded and commented for Asian Smilacaceae, with a key to the sections and species. The main taxonomic treatments are listed as below:Four names are treated as synonyms:Smilax jiankunii H.Li as the synonym of S. pottingeri Prain, S. tsinchengshanensis F.T.Wang as the synonym of S. minutiflora A.DC.,5. hypoglauca Benth. as the synonym of S. corbularia Kunth, S. munita S.C.Chen as the synonym of S. myrtillus A.DC.;A new name, Smilax binchuanensis P.Li&C.X.Fu is proposed for Heterosmilax yunnanensis Gagnep.;Nine new combinations are proposed:Smilax chinensis (F.T.Wang) P.Li&C.X.Fu for Heterosmilax chinensis F.T.Wang, S. japonica (Kunth) P.Li&C.X.Fu for H. japonica Kunth, S. longiflora (K. Y.Gun&Noltie) P.Li&CX.Fu for H. longiflora K.Y.Gun&Noltie, S. micrandra (T.Koyama) P.Li&C.X.Fu for H. micrandra T.Koyama, S. paniculata (Gagnep.) P.Li&C.X.Fu for H. paniculata Gagnep., S. polyandra (Gagnep.) P.Li&C.X.Fu for H. polyandra Gagnep., S. seisuiensis (Hayata) P.Li&C.X.Fu for H. seisuiensis (Hayata) F.T.Wang&Tang, S. septemnervia (F.T.Wang&Tang) P.Li&C.X.Fu for H. septemnervia F.T.Wang&Tang, S. sumatrensis (A.DC.) P.Li&C.X.Fu for H. sumatrensis A.DC.(≡H. borneensis A.DC.);Smilax castaneiflora H.Lev.&Vaniot is recognized to be a distint species, of which S. nigrescens F.T.Wang&Tang ex. P.Y.Li is the junior homonym。2. The discovery of Smilax ligneoriparia C.X.Fu&P.LiThe molecular data, together with the morphological and karyotype evidence, demonstrate beyond reasonable doubt that "woody riparia" is a distinct species that combines features from both the woody, perennial, Old World clade and the herbaceous, annually emergent clade of Smilax. Thus, this new species, S. ligneoriparia could be called a "missing link".3. Phytogeny and Phylogeography of North American herbaceous SmilaxS. jamesii from Northern California is found to be a distinct species, and sister to the herbaceous Smilax for Eastern North America; The so-called seven species in Eastern North America are mixing together phylogenetically, so they are better to be treated as as the S. herbacea complex. The divergence between S. jamesii and the Eastern North American herbaceous Smilax is estimated to be2.33-0.74mya, which fits well with the hypothesis that the common ancestor which has a continuous distribution was forced to move south by the Pleistocene glaciers (2.5-0.01mya), then came into two lineages with the isolation of the North American Cordillera.The Eastern North American herbaceous Smilax exhibits an Appalachian Mountain discontinuity, with one lineage found on either side of it。Multiple refugia are hypothesized to exist on both sides of the Appalachian Mountain, and some may be much closer to the glaciers then generally thought to be. The’driftless area’ is identified as a suitable refugium for some temperate species. Our study provides a first example for understory herbs to persist in the ’driftless area’ during the LGM.