Abstract: Objective　To characterize a species of the genus Tricula and parasitized trematodes in schistosomiasis?endemic areas of Yunnan Province using a molecular analysis, so as to understand their taxonomic positions. Methods　Tricula spp. and Oncomelania snails were collected from Xiangyun County, Yunnan Province, and cercaria parasitizing snails were observed using crushing followed by microscopy. Cercaria parasitizing Tricula snails at various morphologies were sampled using a shedding method. Genomic DNA was extracted from snail soft tissues and cercariae, and the 16S rRNA, COI, 28S rDNA genes in snails and the ND1 and 28S rDNA genes in cercariae were amplified using a PCR assay and sequenced. The species of Tricula snails and their parasitized trematodes was characterized using sequence alignment and phylogenetic analysis. Results　Among 382 Tricula snails detected, there were three types of trematode cercariae found, including the non?forked (20.94%, 80/382), double?forked (3.40%, 13/382) and swallow shapes (7.07%, 27/382). Sequence and phylogenetic analyses showed that the 16S rRNA, COI and 28S rDNA gene sequences of this species of Tricula had high homology to those in Delavaya dianchiensis, and were clustered in a branch. Sequencing analysis of the ND1 and 28S rDNA genes revealed that the non?forked cercariae belonged to the family Pleurogenidae, the swallow?shaped cercariae belonged to the family Opecoelidae, and the double?forked cercariae belonged to another species of the genus Schistosoma that was different from S. sinensium and S. ovuncatum. Conclusion　The species and taxonomy of Triculla spp. and their parasitized trematodes?are preliminarily determined in schistosomiasis?endemic areas of Yunnan Province; however, further studies are required to investigate the more definite taxonomy and pathogenicity.

Key words: Tricula spp., Oncomelania snail, Trematode, Cercaria, 16S rRNA gene, COI gene, 28S rDNA gene, ND1 gene, Schistosomiasis, Yunnan Province

摘要： 目的　对云南省血吸虫病流行区的一种拟钉螺及其寄生吸虫进行分子生物学鉴定，了解其种属分类地位。方法　采集云南省祥云县拟钉螺和钉螺，压碎镜检采集螺软体腹足部组织，并观察其体内尾蚴寄生情况。采用逸蚴法采集拟钉螺寄生的不同形态尾蚴，螺体组织和尾蚴样本分别提取基因组DNA，采用PCR法扩增螺体内16S核糖体RNA（16S rRNA）、细胞色素c氧化酶I （COI）、28S核糖体DNA（28S rDNA）基因及其体内寄生吸虫尾蚴的NADH脱氢酶亚基 1（ND1）、28S rDNA基因，对扩增产物进行测序，并通过序列比对及系统进化分析鉴定样本螺和寄生吸虫种属。结果　共检测拟钉螺样本382只，发现无叉形、双叉形、燕子形等3种形态吸虫尾蚴，阳性率分别为20.94%（80/382）、3.40%（13/382）、7.07%（27/382）。基于16S rRNA、COI、28S rDNA基因的分子进化分析显示，该拟钉螺与滇池德拉维螺（Delavaya dianchiensis）同源性较高、聚在同一个分支。基于ND1、28S rDNA基因的序列分析显示，无叉形尾蚴吸虫属侧殖吸虫科，燕子形尾蚴吸虫属孔肠科，双叉形尾蚴吸虫可能为不同于中华血吸虫（Schistosoma sinensium）和勾形卵血吸虫（Schistosoma ovuncatum）的另一种血吸虫。结论　初步了解了云南省血吸虫病流行区拟钉螺及其寄生吸虫种属分类，但更明确的分类关系和危害性等尚有待深入研究。

关键词: 拟钉螺, 钉螺, 吸虫, 尾蚴, 16S rRNA基因, COI基因, 28S rDNA基因, ND1基因, 血吸虫病, 云南省