中国淡水鱼类寄生碘泡虫（粘体动物）的系统分类学研究

Myxosporea are an economically important group of microscopic metazoan endoparasites, especially infecting the cultured and wild fish. Myxobolus clade, the largest group of Myxosorea,has more than 800 species in the world, and more than 330 species in China.In past,criteria used for classification among myxosporeans include spore morphology, characteristcis of developmental stages,and host and tissue specificity.Especially in China, spore morphology was often used as a sole criterion for Myxobolus species.Therefore, there maybe exist many plausible and mistaken species. It will be great significant for the basic biology and fish disease prevention and control to study the systematic and parasitic specifity of piscine Myxobolus spp.In order to elucidate the species diversity and their phylogenetic relationships, we will take myxobolus species from freshwater fish of China as main object and study them from four aspects including morphology,molecular biology,phylogeny and parasitic specificity.In this program, the research on classical morphology will be perfected,Myxosporea named only by morphological characters will be examined with molecular data to ascertain whether they are valid, some plausible and mistaken species will be effectively identified and some new species,cryptic species or new records will be found,at the same time,the exact location of parasitic will be determined.Moreover,we will analyses the coevolution pattern between Myxobolus species and their hosts,evaluate host specificity, organ specificity or tissue tropism, and explore ways and means of parasite infection of fish Myxobolus spp.The completion of the project will greatly enrich Myxosporea species resources,and provide the strong theoretical basis for correct evaluation of the phylogenic relationship of Myxobolus species from China and even from genus Myxobolus and enhance the international taxonomic status of Chinese fish Myxosporea. At the same time,it will be beneficial to provide theoretical basis for rational evaluation on Myxosporidiosis of Chinese important aquatic economic animals and establish relevant strategy of prevention and control.

碘泡虫是粘体动物的主要类群，也是鱼类重要的后生动物寄生虫，研究碘泡虫的系统分类学和寄生特异性，在其基础生物学和鱼类粘体动物病害防控方面均具有重要意义。本项目以我国淡水鱼类寄生碘泡虫为主要对象，从形态学、分子生物学、寄生特异性和系统发育等方面，开展鱼类碘泡虫的系统分类学与寄生特异性研究。本研究旨在完善碘泡虫的经典形态学研究，用分子数据佐证形态分类学，探明虫体确切寄生部位，厘清误定种和疑难物种，理清碘泡虫分类学的问题，发现新种、挖掘隐存种或新记录；同时，分析碘泡虫与宿主之间的协同进化模式，评价碘泡虫的宿主或器官特异性以及组织向性，探讨碘泡虫的感染途径和方式。本项目的完成将极大丰富鱼类碘泡虫的物种资源，为正确评价我国碘泡虫乃至整个碘泡虫属的系统进化模式和提升我国鱼类碘泡虫在国际上的分类地位提供有力的理论依据，并为我国重要水产经济动物碘泡虫病害的合理评估和相应防治策略的制定提供理论依据。

碘泡虫是鱼类常见的后生动物寄生虫，部分物种寄生能导致鱼体死亡，造成重大经济损失。本项目调查了长江中下游、华北和华南等地区碘泡虫的物种资源，从形态学、分子生物学和系统发育等方面开展了其系统分类学研究，主要结果如下：（1）发现和描述了仙桃碘泡虫等碘泡虫5新种，厘定了1物种，发现新记录和未定种各1个；（2）补充描述了23个物种；（3）以丑陋圆形碘泡虫为模型解析了单产孢型的孢子发生模式和原质体-宿主组织复合体的结构模式，发现丑陋圆形碘泡虫对宿主真皮层具有明显的组织向性；（4）研究了瓶囊碘泡虫等10余种粘体动物的种内形态变异规律，发现来源于不同地区的、同一个宿主不同孢囊以及同一孢囊内的粘体动物广泛存在形态变异，表明仅依据孢子形态特征分类可能导致了大量同名异物种和同物异名种出现，引入寄生特性和分子数据后，分类的准确性得到了极大提升；（5）不同保存方式对孢子形态的存在一定影响，发现5%甲醛能在短期内适用于孢子形态固定；（6）获得了50条碘泡虫核糖体序列，建立了与形态学对应的 DNA 条形码数据库；（7）发现碘泡虫和尾孢虫的尾突是由两个壳瓣的基部延伸而形成，形态上具有同源性。系统发育分析发现尾孢虫属与碘泡虫属均为非单系类群，祖征重溯结果表明尾突特征在碘泡虫分化的过程中多次独立起源，并最终形成现有尾孢虫类群，尾孢虫祖先并不具有尾突结构。尾孢虫属是一个无效属，我们建议将其种类并入碘泡虫属和单极虫属的分类关系；（8）研究了碘泡虫和单极虫的极囊起源与进化，发现单极虫是多系起源，从两个极囊物种演化而来，至少经历了4次独立的分化过程及3种演化模式。本研究丰富了我国碘泡虫的物种资源，补充了分类学数据，解析了粘体动物的系统发育关系，理清了碘泡虫、单极虫和尾孢虫的关系，为碘泡虫病的精准诊断奠定了理论基础。发表本项目标注文章14篇，其中第一标注论文9篇，授权发明专利1项，培养博士5名，硕士2名。