Page 214 - 《水产学报》2026年第01期

1 期 水 产 学 报 50 卷

Morphological, histopathological, and molecular phylogenetic analysis of
Myxobolus acinosus from Cyprinus carpio var. koi

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GUAN Xitao , ZHANG Xiaoyi , DING Peng , ZHOU Fan , MIAO Xiangjun , LIU Yang 1*
(1. School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao 266109, China;
2. Yunnan Academy of Fishery Science, Kunming 650034, China)
Abstract: Myxozoans are important parasitic pathogens of koi carp. In the present study, a Myxobolus species was found to
infect gills of Cyprinus carpio var. koi. In order to identify this Myxobolus species, it was comprehensively described by mor-
phological, histological and molecular methods, and its phylogenetic relationship was inferred as well. We found that the
present Myxobolus species infected the gills of koi carp and formed a number of white plasmodia in all gills. Compared with all
reported Myxobolus species, the present Myxobolus species was morphologically indistinguishable from M. acinosus. Histolo-
gical analysis showed that the plasmodia of the present Myxobolus species developed in gill lamella of host, causing significant
epithelial cell proliferation and congestion in the gills. Its parasitic characteristics are consistent with those of M. acinosus.
BLAST search showed that SSU rDNA sequence of the present Myxobolus species was identical to M. acinosus (Accession
numbers: KX810021-KX810022, MW821466-MW821468). Thus, the morphological, histological and molecular analysis
demonstrated that the present Myxobolus species was conspecific with M. acinosus. Phylogenetic analysis revealed that the
majority of myxozoans infecting the same host and organ formed independent lineages. However, myxozoans infecting differ-
ent hosts and the same organ formed larger independent branches, indicating that sites of infection provide a stronger driving
force for the evolution of myxozoans compared to host group.
Key words: Cyprinus carpio var. koi; Myxosporea; species identification; phylogenetic analysis

Corresponding author: LIU Yang. E-mail: liuyangqzh@qau.edu.cn
Funding projects: National Nature Science Foundation of China (32073012)

https://www.china-fishery.cn 中国水产学会主办 sponsored by China Society of Fisheries
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