【作者】 柳阳；

【导师】 聂品； 顾泽茂；

【作者基本信息】 华中农业大学 ， 水产养殖， 2014， 博士

【摘要】 粘体动物(Myxozoa)是一类世界性分布的后生动物寄生虫,主要寄生于鱼类,能导致鱼类重大病害的发生,并造成严重的经济损失和生态污染。碘泡虫(Myxobolus)是粘体动物的最大类群,全世界报道850多种,我国记录320多种。本文运用形态学、组织学及分子生物学方法,研究了碘泡虫属的分类地位,系统整理了我国的碘泡虫种类,并对采集到的12种碘泡虫进行了鉴定和补充描述。主要结果如下：一、碘泡虫属与尾孢虫属的分类关系研究：(1)本文发现丑陋圆形碘泡虫(Myxobolus turpisrotundus)、苍梧碘泡虫(M. tsangwuensis)、贝壳碘泡虫(M. musseliusae)、口腔碘泡虫(M. oralis)的部分孢子具有与尾孢虫类似的尾突。孢子发生研究显示碘泡虫的尾突与尾孢虫的尾突均由壳瓣基部延伸形成,说明碘泡虫尾突与尾孢虫尾突具有共同的来源和发育过程。(2)利用碘泡虫、尾孢虫及相近种属的18S rDNA序列作为分子标记进行系统发育分析,发现碘泡虫与尾孢虫在系统发育树上交替聚在一起没有形成独立的分支,说明碘泡虫属和尾孢虫属均非单系类群。(3)进化分析发现碘泡虫与尾孢虫的祖先种类不具有尾突,尾突是在后来的进化过程中出现的,并且尾突分化事件在整个进化过程中独立发生了多次。同时,本文发现祖先种类分化出尾突之后还可以在后来的进化过程中再次失去尾突重新形成无尾的种类。综上所述,尾突并非尾孢虫特有的形态特征亦不能代表尾孢虫之间的亲缘关系,无法作为区分碘泡虫属和尾孢虫属的分类指标。经典分类学依据尾突建立的尾孢虫属是一个无效属,加之其与碘泡虫具有极近的亲缘关系又无其他形态差异,应将其并入碘泡虫属。二、中国碘泡虫物种的整理：(1)完善我国碘泡虫物种名录：将我国记录的30种尾孢虫、8种粘体虫修订入碘泡虫属；通过对我国碘泡虫物种进行系统梳理,厘定11物种,其中同名异物9种,同物异名1种,无效种1种,取消41种中国无效记录。(2)明确每个物种的典型宿主和寄生部位：根据首次描述时的宿主为典型宿主的原则明确了我国每个碘泡虫种类的典型宿主和寄生部位。根据上述结果建立了中国碘泡虫名录,包括326个碘泡虫种类,寄生于中国115种淡水鱼类,1种海水鱼类,其中寄生鲫、鲤的碘泡虫种类最多,分别为52种和25种。三、12种碘泡虫的鉴定与补充描述：(1)厘定寄生异育银鲫体表、鳃、鳍条的碘泡虫为丑陋圆形碘泡虫(M. turpisrotundus)而非圆形碘泡虫(M. rotundus)。(2)厘定寄生我国鲤鳃丝的碘泡虫为贝壳碘泡虫(M. musseliusae)而非异型碘泡虫(M. dispar)。(3)鉴定寄生异育银鲫咽部的碘泡虫为洪湖碘泡虫新种(M. honghuensis sp.n.)。(4)鉴定寄生异育银鲫口腔上颌的碘泡虫为口腔碘泡虫新种(M. or alis sp. n.)。(5)依据本文采集种群对山东碘泡虫(M. shantungesis)、野鲤碘泡虫(M. koi)、鲤肠碘泡虫(M. cyprinicola)、吴李碘泡虫(M. wulii)、瓶囊碘泡虫(M.ampullicapsulatus)、倪李碘泡虫(M. nielii)、多涅茨碘泡虫(M. doneci)、鳜碘泡虫(M. sinipercus)等8种碘泡虫的孢子形态、超微结构、寄生特性及18S rDNA序列进行了补足性重描述。更多还原

【Abstract】 Myxozoans are an economically important group of metazoan endoparasites infecting various fish throughtout the world. The diseases caused by them have resulted in mass mortality or loss of economic value of the cultured and wild fish. Myxobolus Butschli,1882is the genera with the greatest number of described species, with over850species identified throughout the world and320species reported in China. In the present paper, we investigated the taxonomy of Myxobolus, made a systematic revisions on Myxobolus species in China, and identified12Myxobolus species by morphological, histological, and molecular methods. The main results are as follows.Taxonamy of Myxobolus and Henneguya:(1) In the present study, the spores of Myxobolus turpisrotundus, M. tsangwuensis, M. musseliusae and M. oralis were observed intermixed with atypical spores bearing caudal appendages. Ultrastructural observation showed that the caudal appendages on both Myxobolus and Henneguya spores came from the elongation of the posterior of the valves.(2) Phylogenetic analysis based on all the available ribosomal DNA sequence data of Myxobolus and Henneguya species still did not support a separation of these two genera.(3) Tracing the history of caudal appendages evolution showed that the morphology of the ancestral species of Myxobolus and Henneguya did not possess the caudal appendages and that caudal appendages have arisen on multiple occasions independently during the evolution. It is worth noting that some Henneguya-type species could lose their caudal appendages to form Myxobolus-type species. The above results indicated that caudal appendages were not a valid character to separate Myxobolus-type and Henneguya-type species into two separate genera. Genus Henneguya is not valid and its species should be assigned to genus Myxobolus.Systematic revisions on the Myxobolus species in China:(1) Revisons on the list of Myxobolus species in China:30Henneguya and8Myxosoma species described in China were assigned to Myxobolus;9homonyms,1synonym,1invalid species, and41invalid Chinese records were identified and removed from the Chinese Myxobolus list.(2) Identification of the type host and the site of infection:the type host and the site of infection of the Myxobolus species in China were identified according to the original descriptions. In conclusion, the list of Myxobolus species in China includes326normal species infecting115different freshwater fish,1marine fish. Among them,52and25species were identified from gold fish and common carp, respectively. Identification and redescription of12Myxobolus species collected in China:(1) The species infecting the skin, gills and fins of gibel carp Carassius auratus gibelio was identified as M. turpisrotundus.(2) The species infecting the gills of common carp Cyprinus carpio was identified as M. musseliusae.(3) The species infecting the pharynx of gibel carp was identified as M. honghuensis sp. n.(4) The species infecting the palate in the mouth of gibel carp was identified as M. oralis sp. n.(5) M. shantungesis, M. koi, M. cyprinicola, M. wulii, M. ampullicapsulatus, M. nielii, M. doneci, and M. sinipercus were redescribed by their morphological, ultrastructural, histological and molecular characteristics.更多还原