中华蛸寄生丛集球虫(顶复亚门:丛集球虫科)新种的形态学与分子生物学研究

MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF A NEW SPECIES OF AGGREGATA(APICOMPLEXA:AGGREGATIDAE)INFECTING OCTOPUS SINENSIS

丛集球虫(顶复亚门:类锥体纲:丛集球虫科)是头足类消化道中一类常见寄生虫,在福建连江海域以及浙江南麂岛周边海域采捕到的中华蛸(Octopus sinensis)盲囊及肠组织内发现一丛集球虫新种,命名为多刺丛集球虫Aggregata octaculeata sp.nov.。光学显微镜和扫描电镜下观察发现,中华蛸体内的多刺丛集球虫存在配子生殖阶段和孢子生殖阶段,其中,孢子生殖阶段成熟卵囊呈近球形或椭球形,长径653.6-806.5μm,短径588.1-787.1μm。孢子囊为卵球形或椭球形,长径22.4-26.1μm,短径20.5-24.6μm,孢子囊壁为双层,外部光滑,内层多刺。孢子囊内子孢子呈卷曲状,数目范围8-13个,子孢子长度为22.2-28.6μm,宽度为3.0-5.0μm。基于18S rRNA基因构建的系统发育树进一步证实该物种隶属于丛集球虫属,并高度支持了属内[(中华丛集球虫A.sinensis+A.octopiana)+A.eberthi]+多刺丛集球虫A.octaculeata的系统发生关系。

Aggregata(Apicomplexa:Conoidasida:Aggregatidae)is one of the commonest parasites that parasitizes in the digestive tract of cephalopods.A new species of parasitic Aggregata,i.e.,Aggregata octaculeata sp.nov.,was identified in Octopus sinensis(Mollusca:Octopodidae)in the waters of Zhejiang and Fujian Provinces based on morphological characters and 18S ribosomal RNA(18S rRNA)gene sequences.Morphological characteristics were described and measured in electron microscopy and light microscopy.Aggregata octaculeata is distinguishable in sporocyst structure(shape,size),number and size of the sporozoites,especially the different forms of sporocyst wall surfaces that possess projections or are spiny.The size of the oocysts is 653.6-806.5μm in length and 588.1-787.1μm in width.Mature sporocysts within oocysts are typically spherical to slightly subovoid and sporocysts are 22.4-26.1μm in length and 20.5-24.6μm in width.Sporozoites are typically spiral within sporocysts.Sporozoites are 22.2-28.6μm in length and 3.0-5.0μm in width.The phylogenetic tree constructed based on 18S rRNA indicates that A.octaculeata belongs to the genus Aggregata.Molecular phylogenetic analyses support the morphological results.Morphological characteristics combined with molecular data show that A.octaculeata is a new species of the genus Aggregata in a host that lives in western Pacific waters.