背景：Myxozoans是一组刺胞寄生虫，目前的分类法有利于结合孢子形态的更全面的表征策略，生物学性状(宿主/器官特异性，组织嗜性)，和经典的基于形态学的分类法的DNA数据。然而,如果同时遇到以下两种以上的例外情况，系统主义者可能会再次陷入分类困境：广泛的种内多态性，种间形态相似性，相同的种间生物学性状和模糊的基于小亚基（SSU）rDNA的物种边界。在本研究中,一种MyxobolusBütschli的孢子，1882年，从鲤鱼CyprinuscarpioLinnaeus的the中收集了两种形态类型（宽型和窄型）。令人困惑的是，宽型被发现与卡托美克索博氏相同，Kasai,Tomochi,Li&Sato,2017年孢子形态和SSUrDNA序列，这自信地表明了它们的特殊性；而狭窄的类型，与MyxobolustoyamaiKudo非常相似，1917基于孢子形态和SSUrDNA序列，因此无法轻易分类。宽型和窄型之间的这种不一致导致了分类学上的困境。为了解决这个问题,提出了一个关于窄型和M.toyamai的共特异性的假设。
结果：发现如果窄型与M.toyamai相同，这将是自相矛盾的SSUrDNA序列的窄型更类似于M.paratoyamai（99.3％），Nie&Li,1973年（98.6%）和长孢子MyxobolusNie&Li，1992年（98.7%）比M.toyamai（97.6%）。根据上述假设分析的结果，窄型和M.toyamai被认为是不同的物种。总而言之，目前的双形态类型物种估计与副马卡托M.paratoyamaiKato相同，Kasai,Tomochi,Li&Sato,2017.考虑到这个物种的名字被MyxobolusparatoyamaiNie&Li所占据，1992年，替换名称假性粘菌。11月。是提议的。
结论：这项工作解决了多态粘液虫的分类学困境，并证明了假刺科是具有两种形态类型的独特物种。本研究可以作为未来研究遇到类似分类复杂性的基线。
BACKGROUND: Myxozoans are a group of cnidarian parasites, the present taxonomy of which favors a more comprehensive characterization strategy combining spore morphology, biological traits (host/organ specificity, tissue tropism), and DNA data over the classical morphology-based taxonomy. However, a systematist might again run into a taxonomic dilemma if more than two of the following exceptional cases were encountered at the same time: extensive intraspecific polymorphism, interspecific morphological similarity, identical interspecific biological traits and blurred small-subunit (SSU) rDNA-based species boundaries. In the present study, spores of a species of Myxobolus Bütschli, 1882 with two morphotypes (wide type and narrow type) were collected from the gills of common carp Cyprinus carpio Linnaeus. Confusingly, the wide type was found to be identical to Myxobolus paratoyamai Kato, Kasai, Tomochi, Li & Sato, 2017 in spore morphology and SSU rDNA sequence, which confidently suggested their conspecificity; while the narrow type, was highly similar to Myxobolus toyamai Kudo, 1917 based on spore morphology and SSU rDNA sequence and thus could not be easily classified. This discordance between wide type and narrow type has caused a taxonomic dilemma. To address this problem, a hypothesis about the conspecificity of the narrow type and M. toyamai was addressed.
RESULTS: It was found that if the narrow type is conspecific with M. toyamai, it would be paradoxical for the SSU rDNA sequence of the narrow type to be more similar to M. paratoyamai (99.3%), Myxobolus acinosus Nie & Li, 1973 (98.6%) and Myxobolus longisporus Nie & Li, 1992 (98.7%) than to M. toyamai (97.6%). According to the results of the above what-if analysis, the narrow type and M. toyamai were considered to be different species. All in all, the present dual-morphotype species is estimated to be conspecific with M. paratoyamai Kato, Kasai, Tomochi, Li & Sato, 2017. Considering that this species name was preoccupied by Myxobolus paratoyamai Nie & Li, 1992, the replacement name Myxobolus pseudoacinosus nom. nov. is proposed.
CONCLUSIONS: This work addresses the taxonomic dilemma in polymorphic myxozoans and demonstrates that M. pseudoacinosus is a distinct species with two morphotypes. The present study may serve as a baseline for future studies that encounter similar classification complexities.
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