Parasitology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India.
Parasitology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India.
Microb Pathog. 2018 Sep;122:191-199. doi: 10.1016/j.micpath.2018.05.038. Epub 2018 May 25.
Fish mortality and poor growth in surviving fish contribute substantial losses to the ornamental fish farms of India and revealed an infection of a new myxosporidian parasite Thelohanellus indiana n. sp. which has become one of the most important limiting factors for successful aquaculture management. The parasite infects Carassius auratus, an Indian goldfish, described on the basis of myxospores morphology and amplification of a part of 18 S rDNA gene. Three major attaching site of fish body have been explored for showing the location of attachment for the parasites. The whitish cysts of the parasites are about 2.5-3.5 mm contains large amount of lemon shaped mature myxospores measuring 12.1-15.2 (13.8) × 7.5-8.8 (8) μm. A single round or elliptical polar capsule located only at the anterior pole of the spore having 6.2-7.2 (6.8) × 3.3-4.7 (4.0) μm in diameter. The morphological characters have been assessed by both the light and scanning electron microscope. The most differentiating feature from closely related species was carried out by morpho-taxonomic affinities with previously described species which are tremendously supported by molecular taxonomy by partial sequencing of the 18 S rDNA gene resulted in a total of 2101 bp fragment of newly obtained SSU rRNA gene sequence of the new species which exhibit 79-91% homogeneity with other closely related species available in GenBank. The BLAST search of Thelohanellus sp. did not matches with any available sequences in GenBank and the phylogenetic analysis revealed that the novel species were sister to T. habibpuri and T. caudatus, in the Thelohanellus clade and form a closest neighboring branch as a subclade in phylogenetic tree from which the new Thelohanellus parasite is being placed. Both the branches are originating from monophyletic clade that are strongly supported by bootstrap values which indicate clearly about independent position of T. indiana n. sp.
印度观赏鱼养殖场的鱼类死亡率和生长不良导致了巨大损失，揭示了一种新的粘孢子虫寄生虫 Thelohanellus indiana n. sp. 的感染，这种寄生虫已成为成功水产养殖管理的最重要限制因素之一。寄生虫感染 Carassius auratus，一种印度金鱼，基于粘孢子形态学和 18S rDNA 基因的一部分扩增进行描述。已经探索了鱼类身体的三个主要附着部位，以显示寄生虫的附着位置。寄生虫的白色囊肿大小约为 2.5-3.5mm，含有大量柠檬形成熟粘孢子，大小为 12.1-15.2(13.8)×7.5-8.8(8)μm。一个单一的圆形或椭圆形极囊仅位于孢子的前极，直径为 6.2-7.2(6.8)×3.3-4.7(4.0)μm。通过光镜和扫描电子显微镜评估了形态特征。与密切相关的物种最具区别的特征是通过形态分类学亲缘关系与以前描述的物种进行评估，这得到了分子分类学的极大支持，部分测序 18S rDNA 基因导致总共获得了 2101bp 的新获得的 SSU rRNA 基因序列片段，与 GenBank 中可用的其他密切相关物种的同源性为 79-91%。Thelohanellus sp.的 BLAST 搜索与 GenBank 中任何现有序列都不匹配，系统发育分析表明，新物种与 T. habibpuri 和 T. caudatus 密切相关，在 Thelohanellus 进化枝中形成一个最接近的分支作为进化树中的一个亚分支，从该进化树中可以确定新的 Thelohanellus 寄生虫的位置。这两个分支都起源于单系进化枝，这得到了自举值的强烈支持，这清楚地表明了 T. indiana n. sp. 的独立地位。
