Plasmodia containing myxospores belonging to the genus Henneguya Thélohan, 1892 were found in the gills of Eugerres brasilianus (Cuvier, 1830). Despite the economic importance, few parasitological studies have been done with this species. We describe Henneguya lagunensis n. sp. using morphological and molecular data. The mature myxospores were rounded, measuring 29.1 ± 2.2 μm in total length, 8.2 ± 1.0 μm in body length, 7.9 ± 0.2 μm in body width, 20.7 ± 2.4 μm in tail length and 4.8 ± 1.0 μm in thickness. The polar capsules measured 3.3 ± 0.4 in length and 1.7 ± 0.3 μm in width. Polar filaments had 4–5 turns, helical. Phylogenetic analysis showed Henneguya lagunensis n. sp. as a sister species of Henneguya cynoscioni Dyková, Buron, Roumillat and Fiala, 2011, within a clade that contained mostly Henneguya species that parasitize marine fish of the order Perciformes. This is the first report of a species of Henneguya parasitizing Eugerres brasilianus.

在Eugerres brasilianus的ill中发现了含有属于HenneguyaThélohan属的粘孢子的疟原虫（Cuvier，1830年）。尽管具有经济重要性，但对该物种进行的寄生虫学研究很少。我们描述了Henneguya lagunensis n。sp。使用形态学和分子数据。成熟的粘孢子是圆形的，全长为29.1±2.2μm，体长为8.2±1.0μm，体宽为7.9±0.2μm，尾长为20.7±2.4μm，厚度为4.8±1.0μm。极性胶囊的长度为3.3±0.4，宽度为1.7±0.3μm。极丝有4-5匝，螺旋形。系统发育分析表明，Henneguya lagunensis n。sp。作为Henneguya cynoscioni的姐妹种Dyková，Buron，Rourmillat和Fiala，2011年，在一个进化支中，大部分包含Henneguya物种，这些物种寄生了Perciformes鱼类。这是Henneguya寄生巴西种Eugerres brasilianus的首次报道。