Purpose

The class Myxozoa consists of microscopic spores that typically present uniform morphological simplifications, containing one or two sporoplasms surrounded by valve cells. The present study analysed the morphological and phylogenetic characteristics of what proved to be a new species of Ceratomyxa found in the gallbladder of Mesonauta festivus Heckel, 1840 captured on the Piririm River in the municipality of Macapá, in Amapá state, Brazil.

Methods

The fish were collected in gillnets, and were transported alive to Amapá State University in Macapá for the analysis of the organs. Crescent- or arch-shaped free spores were observed under light microscopy, containing two polar capsules and a suture line, which is typical of the morphology of the genus Ceratomyxa, contained within plasmodia that had snake-like movements. The gallbladder was conserved in 80% alcohol for the analysis of the 18S rDNA gene, and in Davidson solution for standardhistology.

Results

Ceratomyxa spores (n = 20) were observed in 11 of the 50 samplesanalysed, and thus had a prevalence of 22%, and had a mean length of 4.2 ± 0.5 µm, mean thickness of 22.75 ± 0.3 µm, and two polar capsules, 1.86 ± 0.3 µm long and 1.63 ± 0.1 µm thick.

Conclusions

The phylogenetic analysis indicated that the new species forms a cluster with other freshwater Amazonian Ceratomyxa species, described previously. The new species represents the first description of a taxon of the genus Ceratomyxain fish from the Brazilian state of Amapá.

中文翻译：

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Ceratomyxa macapaensis的形态和系统发育特征。sp。(Myxozoa: Ceratomyxidae) 在 Mesonauta festivus Heckel, 1840 (Cichliformes: Cichlidae) 来自东部亚马逊地区

目的

粘虫类由微小的孢子组成，这些孢子通常呈现出统一的形态简化，包含一个或两个被瓣细胞包围的孢子质。本研究分析了1840 年在巴西阿马帕州马卡帕市的 Piririm 河上捕获的Mesonauta festivus Heckel胆囊中发现的一种新的Ceratomyxa的形态和系统发育特征。

方法

这些鱼被收集在刺网中，并被活运到马卡帕的阿马帕州立大学进行器官分析。在光学显微镜下观察到新月形或拱形的游离孢子，包含两个极囊和一条缝合线，这是典型的Ceratomyxa 属形态，包含在具有蛇状运动的疟原虫中。胆囊保存在 80% 酒精中用于分析 18S rDNA 基因，并保存在戴维森溶液中用于标准组织学。

结果

 在分析的 50 个样品中的 11 个中观察到Ceratomyxa孢子 ( n = 20)，因此患病率为 22%，平均长度为 4.2 ± 0.5 µm，平均厚度为 22.75 ± 0.3 µm，两个极性胶囊，1.86 ± 0.3 µm 长和 1.63 ± 0.1 µm 厚。

结论

系统发育分析表明，该新物种与之前描述的其他淡水亚马逊河豚属物种形成了一个集群。这个新物种代表了巴西阿马帕州鱼类中角足菌属分类单元的首次描述。