Zatti Suellen A, Atkinson Stephen D, Maia Antônio A M, Corrêa Lincoln L, Bartholomew Jerri L, Adriano Edson A
Department of Animal Biology, Institute of Biology, University of Campinas, Caixa Postal 6109, CEP 13083-970, Campinas, São Paulo, Brazil.
Department of Microbiology, Oregon State University, 97331, Corvallis, Oregon, USA.
Parasitol Int. 2018 Oct;67(5):612-621. doi: 10.1016/j.parint.2018.06.005. Epub 2018 Jun 13.
We describe two novel myxosporean parasites from Brachyplatystoma rousseauxii, an economically important freshwater catfish from the Amazon basin, Brazil. Myxobolus tapajosi n. sp., was found in the gill filaments of 23.5% of 17 fish, with myxospores round to oval in frontal view and biconvex in lateral view: length 15 (13.5-17) μm and width 10.7 (9.6-11.4) μm; polar capsules equal, length 5.8 (4.6-7.1) μm and width 3 (2.3-3.8) μm containing polar tubules with 6-7 turns. Ellipsomyxa amazonensis n. sp. myxospores were found floating freely or inside plasmodia in the gall bladder of 23.5% of fish. The myxospores were ellipsoidal with rounded extremities: length 12.8 (12.3-13.6) μm and width 7.6 (6.7-8.7) μm; with two equal, slightly pyriform polar capsules, length 3.8 (3.8-4.0) μm and width 3.1 (2.5-3.4) μm, containing polar tubules with 2-3 turns. We combined spore morphometry, small-subunit ribosomal DNA data, specific host, and phylogenetic analyses, to identify both of these parasites as new myxozoan species. Maximum likelihood and Bayesian analyses showed that Myxobolus tapajosi n. sp. clustered in a basal branch in a subclade of parasites from exclusively South American pimelodid fishes. Ellipsomyxa amazonensis n. sp. clustered within the marine Ellipsomyxa lineage, but we suspect that although the parasite was collected in freshwater, its hosts perform a large migration throughout the Amazon basin and may have become infected from a brackish/marine polychaete host during the estuary phase of its life.
我们描述了两种来自巴西亚马逊河流域经济重要性淡水鲶鱼——鲁氏短平口鲶（Brachyplatystoma rousseauxii）的新型粘孢子虫寄生虫。塔帕若斯碘泡虫（Myxobolus tapajosi n. sp.）在17条鱼中的23.5%的鳃丝中被发现，其粘孢子在正面观时呈圆形至椭圆形，侧面观时为双凸形：长15（13.5 - 17）μm，宽10.7（9.6 - 11.4）μm；极囊相等，长5.8（4.6 - 7.1）μm，宽3（2.3 - 3.8）μm，含有6 - 7圈的极丝。亚马逊椭圆粘体虫（Ellipsomyxa amazonensis n. sp.）的粘孢子在23.5%的鱼的胆囊中自由漂浮或存在于孢质团内。粘孢子呈椭圆形，两端圆形：长12.8（12.3 - 13.6）μm，宽7.6（6.7 - 8.7）μm；有两个相等的、略呈梨形的极囊，长3.8（3.8 - 4.0）μm，宽3.1（2.5 - 3.4）μm，含有2 - 3圈的极丝。我们结合孢子形态测量、小亚基核糖体DNA数据、特定宿主和系统发育分析，将这两种寄生虫鉴定为新的粘孢子虫物种。最大似然法和贝叶斯分析表明，塔帕若斯碘泡虫（Myxobolus tapajosi n. sp.）聚集在一个仅来自南美油鲶科鱼类寄生虫亚分支的基部支系中。亚马逊椭圆粘体虫（Ellipsomyxa amazonensis n. sp.）聚集在海洋椭圆粘体虫谱系内，但我们怀疑尽管该寄生虫是在淡水中采集的，但其宿主在整个亚马逊河流域进行大规模洄游，可能在其生命周期的河口阶段从咸水/海洋多毛类宿主感染。
