Uni Research, Uni Environment, P.O. Box 7810, 5020 Bergen, Norway.
Parasitology. 2011 Aug;138(9):1164-75. doi: 10.1017/S0031182011000916. Epub 2011 Jul 15.
Phylogenetic analyses of SSU rDNA sequences have previously revealed the existence of 2 Ichthyobodo species able to infect Atlantic salmon (Salmo salar L.). Ichthyobodo necator sensu stricto (s.s.) is assumed to be a freshwater parasite, while a genetically distinct but undescribed species, Ichthyobodo sp. II sensu Todal et al. (2004) have been detected on Atlantic salmon in both fresh- and seawater. In the present study a morphological description of Ichthyobodo sp. II from the gills of salmon reared in fresh-, brackish- and seawater is presented, using both light- and electron microscopy. Comparative morphometry show that Ichthyobodo sp. II from both freshwater and seawater displays a different cell shape, and is significantly smaller than I. necator s.s. Also, ultrastructural characteristics distinguish these two species, notably differences in the attachment region and the presence of spine-like surface projections in Ichthyobodo sp. II. Based on both unique SSU rDNA sequences and morphological characteristics, we conclude that Ichthyobodo sp. II. represents a novel species for which we propose the name Ichthyobodo salmonis sp. n.
先前的 SSU rDNA 序列系统发育分析显示，有 2 种能够感染大西洋鲑（Salmo salar L.）的 Ichthyobodo 物种。Ichthyobodo necator sensu stricto（s.s.）被认为是一种淡水寄生虫，而在淡水和海水中均检测到的、在遗传上不同但尚未被描述的物种 Ichthyobodo sp. II，由 Todal 等人（2004 年）检测发现。本研究通过光镜和电镜，对在淡水、半咸水和海水中养殖的鲑鱼鳃部的 Ichthyobodo sp. II 进行了形态描述。比较形态计量学显示，来自淡水和海水的 Ichthyobodo sp. II 表现出不同的细胞形状，并且明显小于 I. necator s.s.。此外，超微结构特征也区分了这两个物种，尤其是在 Ichthyobodo sp. II 的附着区域和存在刺状表面突起方面存在差异。基于独特的 SSU rDNA 序列和形态特征，我们得出结论，Ichthyobodo sp. II. 是一个新的物种，我们提议将其命名为 Ichthyobodo salmonis sp. n.。
