Aquatic Parasitology Laboratory, School of Fisheries, Aquaculture, & Aquatic Sciences, College of Agriculture, Auburn University, 203 Swingle Hall, Auburn, AL, 36849, USA.
Syst Parasitol. 2021 Dec;98(5-6):713-730. doi: 10.1007/s11230-021-10007-3. Epub 2021 Oct 22.
Two new species of Myxobolus Bütschli, 1882 (Bivalvulida: Myxobolidae) are described from the gill of the black redhorse (Moxostoma duquesnei [Leueur][Cypriniformes: Catostomidae]) from the Little Tennessee River Basin, North Carolina, United States. Myxobolus branchiofilum n. sp. infects lumen of the lamellar arterioles and Myxobolus branchiopecten n. sp. infects the bone and cartilage at the tip of the gill rakers. They differ from all congeners by a combination of myxospore dimensions and the presence or absence of an iodinophilic vacuole in the sporoplasm, mucous envelope, intercapsular process, and sutural markings. A phylogenetic analysis of the small subunit ribosomal DNA recovered M. branchiopectin sister to Myxobolus sp. (AF378343) in a clade composed of 6 species of Myxobolus, which infect predominately cypriniform intermediate hosts. Myxobolus branchiofilum was recovered sister to Myxobolus ictiobus Rosser, Griffin, Quiniou, Alberson, Woodyard, Mischker, Greenway, Wise & Pote, 2016 in a clade composed of 8 species of Myxobolus, which predominately infect catostomid intermediate hosts. Histological sections of infected gill revealed intra-lamellar plasmodia of M. branchiofilum in the lumen of the lamellar arterioles and foci of M. branchiopecten developing in the bone and cartilage of the gill raker tip. These are the first myxozoans reported from the black redhorse. Given that these two new species are morphologically congeneric but recovered in distantly related clades, we discuss the persistent issue of myxobolid genera paraphyly/polyphyly.
两种新的粘孢子虫（Bivalvulida: Myxobolidae），即 Myxobolus Bütschli, 1882，被描述为来自美国北卡罗来纳州小田纳西河流域的黑红大马哈鱼（Moxostoma duquesnei [Leueur] [Cypriniformes: Catostomidae]）的鳃。Myxobolus branchiofilum n. sp. 感染了板状动脉的腔，而 Myxobolus branchiopecten n. sp. 则感染了鳃耙尖端的骨和软骨。它们与所有同物异名种的区别在于粘孢子的尺寸以及孢子质、粘液囊、囊间体、缝合线处是否存在碘泡。小亚基核糖体 DNA 的系统发育分析表明，Myxobolus branchiopectin 与 Myxobolus sp.（AF378343）亲缘关系最近，后者存在于一个由 6 种主要感染鲤形目中间宿主的粘孢子虫组成的分支中。Myxobolus branchiofilum 与 Myxobolus ictiobus Rosser, Griffin, Quiniou, Alberson, Woodyard, Mischker, Greenway, Wise & Pote, 2016 亲缘关系最近，后者存在于一个由 8 种主要感染北美的鲷科中间宿主的粘孢子虫组成的分支中。受感染的鳃组织切片显示，Myxobolus branchiofilum 的胞质内体在板状动脉的腔中，而 M. branchiopecten 的病灶则在鳃耙尖端的骨和软骨中发育。这是黑红大马哈鱼首次报道的粘孢子虫。鉴于这两种新种在形态上是同物异名的，但在亲缘关系较远的分支中被发现，我们讨论了粘孢子虫属的并系/多系问题。
