Müller Maria I, Atkinson Stephen D, Bartholomew Jerri L, Adriano Edson A
Universidade Federal de São Paulo, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Diadema, São Paulo, CEP 09972-270, Brazil; Oregon State University, Department of Microbiology, Corvallis, OR, 97331, USA.
Oregon State University, Department of Microbiology, Corvallis, OR, 97331, USA.
Microb Pathog. 2025 Feb;199:107235. doi: 10.1016/j.micpath.2024.107235. Epub 2024 Dec 21.
Myxosporeans are a diverse group of cnidarian endoparasites of aquatic animals, with more than 2600 described species. The genus Ceratomyxa includes some 270 species that are mostly coelozoic and infect the gall bladders of mainly marine fish. During our survey in Tapajós River in the Brazilian Amazon, two Ceratomyxa species were discovered in the gallbladders of the anostomid fishes Schyzodon fasciatus and Schyzodon vittatus. Based on myxospore morphology and sequencing of small subunit ribosomal DNA, we propose that these are novel Ceratomyxa species. Ceratomyxa deformis n. sp. from S. fasciatus and Ceratomyxa anomala n. sp. from S. vittatus are similar in morphology, with mature myxospores slightly arcuate with rounded ends. Plasmodia are elongated, and can move by expanding and contracting the cytoplasm. This amoeboid-like motility is heretofore unreported in freshwater South American Ceratomyxa species. Ultrastructural analyses showed the plasmodial organization of both species comprised a cytoplasmic region harboring organelles and sporogonic stages and an internal large vacuole. Phylogenetic analysis corroborates monophyletic grouping of freshwater Ceratomyxa species from South America. Ceratomyxa deformis n. sp. and C. anomala n. sp., which are the first Ceratomyxa species described in anostomid fishes, grouped as sister taxa to C. gracillima and C. mandi, which infect bile in pimelodid fishes from the Amazon region.
粘孢子虫是水生动物体内多样化的刺胞动物内寄生虫类群，已描述的物种超过2600种。角孢子虫属包括约270个物种，大多为腔寄生，主要感染海鱼的胆囊。在我们对巴西亚马逊地区塔帕若斯河的调查中，在无齿脂鲤科鱼类条纹锯啮脂鲤和带纹锯啮脂鲤的胆囊中发现了两种角孢子虫。基于粘孢子形态和小亚基核糖体DNA测序，我们认为这些是角孢子虫新物种。来自条纹锯啮脂鲤的畸形角孢子虫新种和来自带纹锯啮脂鲤的异常角孢子虫新种在形态上相似，成熟粘孢子略呈弓形，两端圆润。孢原质呈细长形，可通过细胞质的伸缩移动。这种类似变形虫的运动此前在南美洲淡水角孢子虫物种中未见报道。超微结构分析表明，这两个物种的孢原质组织包括一个含有细胞器和孢子生殖阶段的细胞质区域以及一个内部大液泡。系统发育分析证实了来自南美洲的淡水角孢子虫物种的单系类群。畸形角孢子虫新种和异常角孢子虫新种是首次在无齿脂鲤科鱼类中描述的角孢子虫物种，它们作为姐妹类群与感染亚马逊地区油鲶科鱼类胆汁的纤细角孢子虫和曼氏角孢子虫归为一类。
