The present study describes a new species of myxosporean, Auerbachia ignobili n. sp., infecting the hepatic bile ducts of Caranx ignobilis (Forsskål, 1775). Myxospores are club-shaped with a broad anterior region and a narrow, slightly curved and blunt caudal extension, measuring 17.4 ± 1.5 μm in length and 7.5 ± 7.4 μm in width. Shell valves asymmetrical, with a faint suture line, and enclosed a single, elongate-elliptical polar capsule with a ribbon-like polar filament, arranged in 5–6 coils. Developmental stages included early and late presporogonic stages, pansporoblast, and sporogonic stages with monosporic and disporic plasmodia. A. ignobili n. sp. differs from the other described species of Auerbachia in the shape and dimensions of the myxospores and polar capsules. The molecular analysis generated ∼1400 bp long SSU rDNA sequences and the present species exhibited a maximum similarity 94.04–94.91% with A. chakravartyi. Genetic distance analysis indicated the lowest interspecies divergence of 4.4% with A. chakravartyi. In phylogenetic analysis, A. ignobili n. sp. was positioned independently with a high bootstrap value (1/100) and appeared as sister to A. maamouni and A. chakravartyi. Fluorescent in situ hybridization and histology indicates that the parasite develops within the hepatic bile ducts. Histological studies did not reveal any pathological changes. Considering the morphological, morphometric, molecular, and phylogenetic differences coupled with the differences in host and geographic locations, the present myxosporean is treated as a new species and named A. ignobili n. sp.

本研究描述了粘孢子菌的一个新种，Auerbachia ignobili n。sp.，感染Caranx ignobilis的肝胆管（Forsskål，1775）。粘孢子呈棒状，具有宽阔的前部区域和狭窄、略微弯曲且钝的尾部延伸，长度为 17.4 ± 1.5 μm，宽度为 7.5 ± 7.4 μm。壳瓣不对称，有微弱的缝合线，并封闭一个单一的、细长椭圆形的极性胶囊，其中带有带状极性丝，排列成 5-6 个线圈。发育阶段包括早期和晚期前孢子发生阶段、全孢子母细胞和具有单孢子和散孢子疟原虫的孢子发生阶段。A. ignobili n. 伊诺比利 sp。与其他描述的奥尔巴克氏菌物种不同粘孢子和极性胶囊的形状和尺寸。分子分析生成了约 1400 bp 长的 SSU rDNA 序列，本物种与A. chakravartyi 的最大相似度为 94.04-94.91%。遗传距离分析表明， A. chakravartyi的种间差异最低，为 4.4% 。在系统发育分析中，A. ignobili n。sp。独立定位，具有较高的引导值 (1/100)，并作为A. maamouni和A. chakravartyi的姐妹出现。荧光原位杂交和组织学表明该寄生虫在肝胆管内发育。组织学研究未发现任何病理变化。考虑到形态、形态测量、分子和系统发育的差异以及寄主和地理位置的差异，目前的粘孢子虫被视为一个新种，并命名为A. ignobilin。sp。