目的 鉴定鄱阳湖区救护死亡的1只白琵鹭十二指肠分离的10条吸虫种类，分析线粒体DNA（mtDNA）中细胞色素C氧化酶Ⅰ亚基（cox1）和核糖体DNA（rDNA）内转录间隔区（ITS）序列特征及遗传进化亲缘关系。方法 光学显微镜下观察白琵鹭十二指肠分离到的吸虫虫体形态结构，挑取3条虫体进行盐酸卡红染色，显微镜下根据形态初步鉴定属种。另挑取3条提取虫体DNA，PCR扩增cox1基因和ITS序列并测序。在GenBank数据库中与类似序列进行同源性检索比对，进行DNA重复计算和碱基含量分析，以日本血吸虫为cox1基因和ITS序列的外群，计算种内/种间遗传距离，邻接法构建系统进化树。结果 分离到的10条吸虫虫体肥厚，淡红色，长度为（14.75 ± 1.89）mm，头领呈明显双叶状，且宽于虫体，头棘末端为钝杆状。盐酸卡红染色结果显示，虫体头棘数量为58~59枚，角棘数量为4枚。3条虫体cox1基因和ITS序列长度为426、985 bp。cox1基因序列碱基组成中，A + T的含量（61.74%）高于C + G含量（38.26%），呈AT偏好性；ITS碱基组成中，A + T的含量（46.10%）低于C + G含量（53.90%），呈GC偏好性。虫体cox1基因、ITS1和5.8SrRNA基因序列无重复序列，ITS2序列有10 bp反向重复序列。cox1基因与冠缝属吸虫（GenBank：OQ606520）同源性为92.86%，遗传距离最近，为0.079；ITS序列与二叶冠缝吸虫（GenBank：ON141921）同源性为98.57%，遗传距离最近，为0.014。在系统进化树上该虫与冠缝属吸虫处在同一小分支，处于棘口科大分支。结论 结合形态学和分子生物学鉴定结果，确认白琵鹭体内分离的吸虫为二叶冠缝吸虫。

Objective To identify the species of 10 trematodes isolated from a dead adult Platalea leucorodia that had been rescued in the Poyang Lake area, and to analyze the sequence characteristics and genetic and evolutionary relationships of mitochondrial DNA (mtDNA)-encoded cytochrome C oxidase subunit I (cox1) gene and ribosomal DNA (rDNA)-encoded internal transcribed spacer (ITS) sequence. Methdos A trematode worm body-shaped structure isolated from the duodenum of P. leucorodia was observed under an optical microscope, and three worms were selected for hydrochloric acid carmine staining and preliminary identification of genus and species under a microscope. In addition, genomic DNA was extracted from another three selected worm samples for PCR amplification of cox1 and ITS sequences, and the amplification products were sequenced. Sequence alignment and homology search were performed in the GenBank database, and repetitive DNA and base content were estimated. Schistosoma japonicum cox1 and ITS sequences were selected as outgroups to estimate intraspecies and interspecies genetic distances, and to build phylogenetic trees with the neighbor-joining (NJ) method. Results Isolated ten trematode worms were fleshy and thick in shape and pale red in color, with a mean length of (14.75 ± 1.89) mm. The cephalic collar was distinctly bilobed and wider than the worm body, and the head spines had blunt rod-shaped ends. Hydrochloric acid carmine staining revealed that the worm body had 58 to 59 head spines, and 4 angular spines. The cox1 gene and ITS sequences of the three trematodes have lengths of 426 and 985 bp, respectively. In the base composition of the cox1 gene sequence, the content of A + T (61.74%) was significantly higher than that of C + G (38.26%), indicating a marked AT bias. Conversely, in the base composition of the ITS gene sequence, the content of A + T (46.10%) was lower than that of C + G (53.90%), showing a GC preference. No repetitive sequences were detected in the cox1, ITS1, or 5.8S rRNA gene sequences of the trematodes, whereas a 10 bp inverted repetitive sequence was identified in the ITS2 gene sequence. The cox1 gene sequence of the trematode exhibited a 92.86% homology and the closest genetic distance (0.079) with Patagifer (GenBank accession number: OQ606511), and the ITS sequence of the trematode showed a 98.57% homology and the closest genetic distance (0.014) with P. bilobus (GenBank accession number: ON141921). The trematode shared the same small clade with trematodes of the genus Patagifer within the large clade of Echinostomatidae. Conclusion Morphological and molecular biological identification confirms the trematode isolated from P. leucorodia as P. bilobus.