Page 187 - 《水产学报》2025年第12期

张金叶，等 水产学报, 2025, 49(12): 129414

[25]
sp. NEO-7 (Fig. 1). Therefore, the above molecular tilage, gill arch cartilage and other tissues . Since
and phylogenetic evidence conclusively demon- the physiological roles of different gill regions vary,
strates that the present organism and Neoactin- the harmfulness of gill myxosporidiosis differs
omyxum sp. NEO-7 represent the alternate develop- accordingly these sites. For example, Myxobolus
mental stages of a single myxozoan species, corres- basilamellaris Lom et Monár, 1983 resides between
ponding to the myxosporea (vertebrate-infecting) the afferent and efferent arteries of the gill filament
and actinosporea (annelid-hosted), respectively. base, which potentially blocks blood flow and lead
Moreover, tissue tropism serves as another critical to insufficient blood supply in gill filament, further
[27]
diagnostic criterion for the myxozoan identification, injury the respiratory function of gills . Thereby, it
and lots of results have proved that different is considered with potential pathogenicity to host.
myxosporean species prefer to colony in the spe- Conversely, myxobolids such as Myxobolus meiji-
cific niche, even if parasitizing the same organs and angensis Zhang et al., 2023, Myxobolus dajiangen-
tissues [3, 25-26] . In this study, although both the present sis Wang et al., 2022 and Myxobolus pyramidis
species and T. wangi parasitize gill filaments, the Chen, 1958 inhabiting the gill lamellae, generally
present species infects the tips of C. auratus gill fil- elicit local inflammatory responses, even if bring
aments, while T. wangi infects basolateral of C. out lamellae hyperplasia and fusion [28-30] . Similarly,
gibelio gill filaments (Plate I-2, Plate II-4, Tab. C. gibelio infected by Myxobolus sheyangensis Liu
[19]
1) . According to Molnár’s guidelines and histolo- et al., 2016 exhibits no prominent inflammatory
gic results from the present study, the present Thel- response, despite local proliferation of connective
[31]
ohanellus species categorized the intrafilamental- tissue and collagen fibers . Thus, these myxobol-
[25]
vascular type 2 (Plate II-10 and 11) . Furthermore, ids is recognized harmless to fish hosts. However,
T. hovorkai parasitize in the gallbladder and kidney the facts that not only the deformation and fracture
of the same hosts, besides the gills; in contrast, T. of gill filaments, the hyperplasia and fusion of gill
hokiangensis, T. wuhanensis and T. kitauei are not lamellae, but also the presence of numerous eosino-
the gills, but rather the skin, ureter and intestine [19-20] . phil cells surrounding myxoplasmodia tissues in the
Therefore, the present species share inconsistent fused gill lamellae, can be easily observed in the
parasitic sites compared with other morphological present study. Notably, T. xiushanensis n. sp.
formed large nidus near the tips of the gill filament,
similar species. Lastly, divergent host specificity is
exhibited between the present species and these which directly compressed and deformed the affer-
ent/efferent artery, obscured the original gill lamel-
compared Thelohanellus species (Tab. 1). In short,
all these results indicate that the present species and lae structure, finally decreased the gas exchange and
weaken the gill respiratory function. Consequently,
Neoactinomyxum sp. NEO-7 are the same organism,
the harmfulness was notable enhanced compared to
which is distinct from the others and recognized
the infections by M. dajiangensis, M. sheyangensis
herein as a new species, named T. xiushanensis n. sp..
and M. pyramidis [28, 30-31] . Therefore, like M. basil-
This new species has been registered in ZooBank
amellaris, T. xiushanensis n. sp. is considered as a
(http://zoobank.org/), with the ZooBank LSIDs
potential harmful pathogen, which should pay more
(Life Science Identifiers) for this publicationbeing:
attention.
1116B7E3-78C4-42FC-BA59-A1A03 D183CAD.
Fish gill myxosporidiosis is the prevalent and
4 CONCLUSION
exemplary case of myxosporidiosis, elicited by the
[1]
gill-parasitizing myxosporean pathogens . The This study presents sufficient taxonomic data
pathogens can colonize various gill locations, such to delineate a new species, named T. xiushanensis n.
as gill lamellae, gill filament base, gill filament car- sp. and correslates the different life stages of one

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