A novel microsporidial disease was documented in two ornamental fish species, black tetra Gymnocorymbus ternetzi Boulenger 1895 and cardinal tetra Paracheirodon axelrodi Schultz 1956. The non-xenoma-forming microsporidium occurred diffusely in most internal organs and the gill, thus referring to the condition as tetra disseminated microsporidiosis (TDM). The occurrence of TDM in black tetra was associated with chronic mortality in a domestic farmed population, while the case in cardinal tetra occurred in moribund fish while in quarantine at a public aquarium. Histology showed that coelomic visceral organs were frequently necrotic and severely disrupted by extensive infiltrates of macrophages. Infected macrophages were presumed responsible for the dissemination of spores throughout the body. Ultrastructural characteristics of the parasite developmental cycle included uninucleate meronts directly in the host cell cytoplasm. Sporonts were bi-nucleated as a result of karyokinesis and a parasite-produced sporophorous vesicle (SPV) became apparent at this stage. Cytokinesis resulted in two spores forming within each SPV. Spores were uniform in size, measuring about 3.9 ± 0.33 long by 2.0 ± 0.2 μm wide. Ultrastructure demonstrated two spore types, one with 9–12 polar filament coils and a double-layered exospore and a second type with 4–7 polar filament coils and a homogenously electron-dense exospore, with differences perhaps related to parasite transmission mechanisms. The 16S rDNA sequences showed closest identity to the genus Glugea (≈ 92%), though the developmental cycle, specifically being a non-xenoma-forming species and having two spores forming within a SPV, did not fit within the genus. Based on combined phylogenetic and ultrastructural characteristics, a new genus (Fusasporis) is proposed, with F. stethaprioni n. gen. n. sp. as the type species.

在两种观赏鱼中发现了一种新型的微孢子病，一种是黑色的四棱Gym（Gymnocorymbus ternetzi Boulenger 1895）和主要的四棱Para舒尔茨1956年。非Xenoma形成的微孢子虫散布在大多数内部器官和腮中，因此称为四弥散性微孢子虫病（TDM）。在国内养殖人口中，黑四肢中TDM的发生与慢性死亡率有关，而四肢主红发生在垂死鱼中，而在公共水族馆隔离。组织学显示，结肠腔内脏器官经常坏死，并被大量巨噬细胞浸润严重破坏。假定感染的巨噬细胞负责孢子在全身的传播。寄生虫发育周期的超微结构特征包括直接在宿主细胞细胞质中的单核梅花。核仁运动导致孢子双核化，在此阶段明显出现了寄生虫产生的孢子囊（SPV）。细胞分裂导致每个SPV内形成两个孢子。孢子大小均匀，长约3.9±0.33 x宽2.0±0.2μm。超微结构显示出两种孢子类型，一种具有9-12个极性细丝线圈和一个双层外孢子，另一种具有4-7个极性细丝线圈和一个均匀的电子致密外孢子，其差异可能与寄生虫的传播机制有关。16S rDNA序列显示与该属最接近的同一性 一种带有9-12个极性细丝线圈和一个双层外孢子，另一种带有4-7个极性细丝线圈和一个均匀的电子致密外孢子，其差异可能与寄生虫的传播机制有关。16S rDNA序列显示与该属最接近的同一性 一种带有9-12个极性细丝线圈和一个双层外孢子，另一种带有4-7个极性细丝线圈和一个均匀的电子致密外孢子，其差异可能与寄生虫的传播机制有关。16S rDNA序列显示与该属最接近的同一性Glugea（≈92％）虽然发育周期，特别是非形成Xenoma的物种，并且在SPV内有两个孢子形成，但并不适合该属。结合系统发育和超微结构特征，提出了一种新的属（Fusasporis），即F. stethaprioni n。gen。。sp。作为类型种类。