Abstract：
Although parasitic copepods of the genus Ergasilus von Nordmann, 1832 are globally distributed parasites of fish, their phylogenetic relationships with other Copepoda are not clear, and the characteristics of their mitochondrial genomes (mitogenomes) are not thoroughly understood. The objective of this study was to address these knowledge gaps by sequencing the complete mitogenome of Ergasilus tumidus Markevich, 1940. The complete mitogenome (GenBank Acc. No. OQ596537) was 14,431 bp long and it comprised 13 protein-coding genes (PCGs), 22 tRNAs, two tRNAs, and two control regions (CRs). Phylogenetic analyses, conducted using concatenated nucleotide and amino acid sequences of 13 protein-coding genes, produced two partially incongruent topologies. While the order Calanoida was consistently resolved as the sister lineage to the other three orders, topological instability was observed in the relationships of the orders Cyclopoida, Siphonostomatoida and Harpacticoida. Siphonostomatoida clustered with Cyclopoida in the nucleotide-based phylogeny, but with Harpacticoida in the amino acid-based phylogeny. The latter topology conforms to the widely accepted relationships, but we speculate that the former topology is more likely to be the correct one. Our study provides a complete mitogenome sequence of E. tumidus, which helps us better understand the molecular evolution of the genus Ergasilus. Additionally, we suggest a different perspective on the controversial phylogenetic relationships among Siphonostomatoida, Cyclopoida and Harpacticoida, diverging from previously accepted views.
摘要：
尽管ErgasilusvonNordmann属的寄生co足类动物，1832年是全球分布的鱼类寄生虫，它们与其他co足类动物的系统发育关系尚不清楚，它们的线粒体基因组（有丝分裂基因组）的特征还没有被彻底理解。这项研究的目的是通过对ErgasilustumidusMarkevich的完整有丝分裂基因组进行测序来解决这些知识空白，1940.完整的有丝分裂基因组（GenBankAcc。不。OQ596537)长14,431bp，包含13个蛋白质编码基因(PCGs)，22个tRNA，两个tRNA，和两个控制区(CR)。系统发育分析,使用13个蛋白质编码基因的串联核苷酸和氨基酸序列进行，产生了两个部分不一致的拓扑。虽然Calanoida命令一直被解决为其他三个命令的姐妹血统，在Cyclopoida阶的关系中观察到拓扑不稳定性，鼻咽口齿和咽喉。在基于核苷酸的系统发育中，虹吸虫与Cyclopoida成簇，但是Harpacticoida在基于氨基酸的系统发育中。后一种拓扑符合广泛接受的关系，但是我们推测前一种拓扑更有可能是正确的。我们的研究提供了完整的有丝分裂基因组序列，这有助于我们更好地了解Ergasilus属的分子进化。此外,我们提出了一个不同的观点，对有争议的系统发育关系，Cyclopoida和Harpacticoida，与先前接受的观点不同。
