Page 179 - 《水产学报》2025年第12期

2025, 49(12): 129414 JOURNAL OF FISHERIES OF CHINA

DOI: 10.11964/jfc.20250515001

Morphological and molecular characterization of
Thelohanellus xiushanensis n. sp. infecting the gill

filament of Carassius auratus

第一作者：张金叶，副教授、硕士生
导师，从事鱼类寄生黏孢子虫的分类
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ZHANG Jinye , WANG Miaomiao , WANG Yueru , LIU Hongyan , 学，分子系统学，病理学，免疫学等
相关研究，E-mail：yjz0916@163.com；
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ZHANG Yiwen , ZHAO Yuanjun 1* 王苗苗，从事鱼类寄生黏孢子虫分类
1. Chongqing Key Laboratory of Conservation and Utilization of Freshwater Fishes, 学及病理学研究，E-mail：1213775365@
qq.com
Chongqing Normal University, Chongqing 401331; 2. Animal Biology Key Laboratory
of Chongqing Education Commission, Chongqing Normal University, Chongqing 通信作者：赵元莙，教授，长期致力
于鱼类寄生虫的分类学、分子系统学、
401331 进化生物学及病害学等相关研究，E-
mail：zhaoyuanjuncqnu@126.com

资助项目：国 家 自 然 科 学 基 金
Abstract: The exploration and understanding of myxosporean, one of the crucial stressors
(31970409)；重庆市科技局重点项目
causing fish disease, have always been highly regarded. The present study aims to fully (cstc2021jcyj-msxmX0731)

understand a novel myxobolid species, Thelohanellus xiushanensis n. sp. infecting the gill 收稿日期：2025-05-20
修回日期：2025-07-01
filaments of Carassius auratus from Chongqing, China, as well as the associated patholo-
文章编号：
gical impacts. A multifaceted analysis at various levels and perspectives was carried out 1000-0615(2025)12-129414-12
中图分类号：S 941.5
by the approach integrating morphology, molecular systematics, histopathology, com-
文献标志码：A

bined host and habitat, as well as SSU rDNA data. The results indicated that its mature
作者声明本文无利益冲突
myxospores displayed a tapering anterior and a blunt-rounded posterior, with a drop-
© 《水产学报》编辑部(CC BY-NC-ND 4.0)
shape in front view and melon-seed shape in sutural view in morphology. The outer sur- Copyright © Editorial Office of Journal of
Fisheries of China (CC BY-NC-ND 4.0)
face was covered with a transparent membrane sheath in valve view. The dimensions of
myxospores were average (19.2 ± 1.1) (17.1-21.0) × (10.0 ± 0.7) (8.7-12.1) × (9.7 ± 0.5)
(9.1-10.8) μm. An elliptical polar capsule, containing four to five turns of single polar fila-
ment, measures (8.0 ± 0.6) (6.9- 9.1) × (6.6 ± 0.3) (6.1-7.1) μm. Its SSU rDNA sequence
demonstrated the closest similarity (99.95%) with an actinosporean Neoactinomyxum sp.
NEO-7. Histopathological results indicated that numerous myxoplasmodia of T. xiushan-
ensis n. sp. were located in the tips of the gill filaments, resulting in deformation and rup-
ture of partial gill filaments. Furthermore, severely infected gill lamellae exhibited hyper-
plasia and fusion, accompanied by infiltration of numerous eosinophils. In addition,
regenerated gill filaments were observed at the bases of partially ruptured gill filaments,
indicating that the host’s gill tissue has the innate capacity to shed diseased tissues and
regenerate new ones. This study has proved the present species and Neoactinomyxum sp.
NEO-7 belong to the same myxosporean species but corresponding to different develop-
mental stage, designated as a new species. This novel species is a potential pathogen for
the host, which should not be ignored. This study not only enriches myxobolid biod-
iversity and demonstrates a potentially pathogenic agent, but also provides a valid dia-
gnosis for the gill myxoboliosis caused by the present pathogen in aquaculture.

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