Levy Michael G, Litaker R Wayne, Goldstein Robert J, Dykstra Michael J, Vandersea Mark W, Noga Edward J
Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, 27606 USA.
J Parasitol. 2007 Oct;93(5):1006-15. doi: 10.1645/GE-3585.1.
All dinoflagellates that infest the skin and gills of fish have traditionally been placed within the class Blastodiniphyceae. Their relatedness was primarily based upon a similar mode of attachment to the host, i.e., attachment disc with holdfasts. Results of recent molecular genetic analyses have transferred these parasites, including Amyloodinium, to the class Dinophyceae, subclass Peridiniphycidae. In our study, a small subunit rDNA gene from a parasitic dinoflagellate that has features diagnostic for species in the genus Piscinoodinium, i.e., typical trophont with attachment disc having rhizocysts, infesting the skin of freshwater tropical fish, places this organism within the dinophycean subclass Gymnodiniphycidae. This suggests a close relationship of Piscinoodinium spp. to dinoflagellates that include symbionts, e.g., species of Symbiodinium, and free-living algae, e.g., Gymnodinium spp. These molecular and morphological data suggest that evolution of this mode of fish ectoparasitism occurred independently in 2 distantly related groups of dinoflagellates, and they further suggest that the taxonomic status of parasites grouped as members of Piscinoodinium requires major revision.
所有寄生于鱼类皮肤和鳃的甲藻传统上都被归为芽甲藻纲。它们的亲缘关系主要基于与宿主相似的附着方式，即带有固着器的附着盘。最近的分子遗传学分析结果已将这些寄生虫，包括淀粉卵甲藻，转移到了甲藻纲、多甲藻亚纲。在我们的研究中，一种寄生甲藻的小亚基核糖体DNA基因具有皮栖甲藻属物种的诊断特征，即典型的营养体带有具有根状囊的附着盘，寄生于淡水热带鱼的皮肤，这表明该生物属于裸甲藻亚纲。这表明皮栖甲藻属物种与包括共生体（如共生藻属物种）和自由生活藻类（如裸甲藻属物种）的甲藻关系密切。这些分子和形态学数据表明，这种鱼类体外寄生方式的进化在两个远缘相关的甲藻类群中独立发生，并且它们进一步表明，作为皮栖甲藻属成员归类的寄生虫的分类地位需要重大修订。
