广西报春苣苔属一新种及其系统位置(英文)

报春苣苔是一类生长在石灰岩基质上的多年生草本植物,目前已知的种类160余种,主要分布在我国南部和越南北部的石灰岩地区。该属植物许多种类分布极其狭域,往往仅零星分布在某个或少数几个地点。近年来,该属植物许多新种类不断地被发现和报道,预示着该属植物可能有更加丰富的多样性。该研究报道了在广西博白县发现的该属植物一新种。从形态上判断,该新种属于广义报春苣苔属,其具有的一些特别的形态特征,如花冠下唇比上唇长得多,上唇内部具有两个近圆形斑点(其它多数种类具有条形斑点),而易于与本属其它物种区分。而且,基于叶绿体mat K基因序列重建的系统发育关系表明,该新种的确属于报春苣苔属且广义报春苣苔属是单系类群。该新种与钟冠报春(P.swinglei)和疏花报春(P.laxiflora)最为近缘,其mat K基因与后两者分别有5个和11个碱基差异,暗示这些物种间经历了较长时间的独立演化或mat K基因在这些物种中具有较高的碱基替换速率。另外,该新种只生长在丹霞岩石上,而其近缘种以及同属大多数其它种类都生长在石灰岩基质上,暗示该新种获得了特殊的适应能力以及与其它近缘种间存在生态隔离。该新种以及近年来本属许多其它新种类的发现,进一步增加了对该属植物多样性的认识,以及该属植物的演化与多样性分化之谜。这些物种所具有的高度区域或局域特有性和稀有性,以及形态上的特殊性和遗传上的独立性,进一步强化了对该属植物开展保护的重要性。

Primulina bobaiensis, a new species of Gesnericaeae from Guangxi, China and its phylogenetic placement revealed by the chloroplast matK gene

Primulina(Gesneriaceae)is an enigmatic group of lithophytic plants, which encompass over 160 species mainly distributed in the limestone region of southern China and nothern Vietnam. A majority of species of the genus have very narrow distribution, which have been found in only one or a few proximate localities. It seems that this genus could even possess much more diversity than presently known as lots of new species have recently been and are being discribed,particularly from its distributional center. In the presnt study, a new species of Gesneriaceae, P. bobaiensis from Guangxi, China is described and illustrated. We intuitively judged the higher taxonomic unit,i.e. genus,that the assumed new species should belong to; compared the morphologies of this assumed new species with all other recognized species previously discribed in the genus and deduced possible close relatives of the new species based on morphological similarity. Then we tested its affinities to other sampled species from the same large region and the divergence of DNA sequences between the assumed new species and its closest relatives. Morphologically,this new species is assumed to belong to the genus Primulina and can be easily distinguished from all other Gesneriaceae species by its special floral appearance,e.g. lower lip is much longer than upper lip and it has spotted marks on the inside of the upper lip(the majority of other species have striped marks on the inside(s)of the lower and/or upper lips). Subsequently,the taxonomic treatment of being attibuted to Primulina and the monophyly of the recircumscribed genus Primulina s.l. are also corroborated by the molecular evidence based on the plastid matK gene. Within the genus the new species is suggested to be the sister of a lineage comprising P. swinglei and P. laxiflora. Further examination of the matK sequences indicated 5 and 11 base differences of P. bobaiensis separating from P. swinglei and P. laxiflora, respectively, implying potential long period of isolation from these species or high substitution rate of the matK gene in these taxa. Moreover, the new species is restricted on Danxia rocks while its closest relatives as well as most of its congeners are confined on limestone rocks,suggesting possible specific edaphic adaptation and isolation of the new species. Further, the high endemism with low abundance and usually morphological and molecular distinctiveness of this and many other species of Primulina would also superimpose the importance of conservation of these rare species.