Bueno Veronica M, Caira Janine N
Department of Ecology & Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd., Storrs, Connecticut, 06269-3043, U.S.A.
Department of Ecology & Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd., Storrs, Connecticut, 06269-3043, U.S.A..
Zootaxa. 2023 Mar 9;5254(1):30-50. doi: 10.11646/zootaxa.5254.1.2.
This paper aims to expand understanding of a poorly known group of cestodes that parasitize an intriguingly diverse suite of elasmobranchs. The group's three currently described members (i.e., Pentaloculum macrocephalum, Pentaloculum hoi, and Zyxibothrium kamienae) parasitize an electric ray, a carpet shark, and a skate, respectively. Pentaloculum grahami n. sp. is described from a second genus of carpet shark, specifically Parascyllium collare, in Australia. Zyxibothrium duffyi n. sp. and Zyxibothrium healyae n. sp. are described from the deep-sea skates Brochiraja asperula and Brochiraja spinifera, respectively off New Zealand. The three new species share distinctive bothridia that bear a small number of large, circular, facial loculi and lateral bands of vitelline follicles that converge posterior to the ovary-features which are found in all other members of these genera. Zyxibothrium healyae n. sp. is unique in possessing three, rather than four or five, facial loculi. Zyxibothrium duffyi n. sp. possesses a combination of five facial loculi and vitelline follicles that stop short of the anterior margin of the proglottid. Pentaloculum grahami n. sp. is the largest member of the group with the greatest number of proglottids. Based on striking similarities in scolex morphology, Pentaloculum and Zyxibothrium have been hypothesized to belong to a distinct subgroup of "tetraphyllideans" provisionally designated as Clade 1. Based on sequence data for the D1-D3 region of the 28S rDNA gene generated for species of Zyxibothrium for the first time, we confirm the reciprocal monophyly of both genera as well as the monophyly of Clade 1 and its status as a distinct lineage among the "Tetraphyllidea". This work also suggests that the presence of five facial loculi is homoplasious given this character state is found in members of both genera. The new species expand the host associations of Clade 1 to include additional skate and carpet shark genera. Moving forward we would expect to find additional members of this group parasitizing other species of parascyliid carpet sharks as well as other species of the rajid genus Malacoraja and the arhynchobatid genus Brochiraja. Here we have doubled the number of described species in the taxon referred to as Clade 1 while simultaneously expanding our understanding of the morphology and anatomy of its members. This additional information will help inform the ultimate revision of the ordinal classification of the cestodes to address the highly polyphyletic nature of the order "Tetraphyllidea" as it is currently configured.
本文旨在拓展对一类鲜为人知的绦虫的认识，这类绦虫寄生于种类多样、颇为有趣的板鳃亚纲鱼类。该类群目前已描述的三个成员（即巨头五叶槽绦虫、何氏五叶槽绦虫和卡氏合叶槽绦虫）分别寄生于电鳐、地毯鲨和鳐鱼。格雷厄姆五叶槽绦虫新种是从澳大利亚地毯鲨的第二个属，即科氏副须鲨中发现并描述的。达菲合叶槽绦虫新种和希利亚合叶槽绦虫新种分别是从新西兰海域的深海鳐鱼粗糙长吻鳐和刺长吻鳐中发现并描述的。这三个新物种具有独特的吸槽，其上有少量大的圆形面叶孔，以及卵黄滤泡的侧带，这些侧带在卵巢后方汇聚，这些特征在这些属的所有其他成员中都有发现。希利亚合叶槽绦虫新种的独特之处在于其有三个而非四个或五个面叶孔。达菲合叶槽绦虫新种具有五个面叶孔和在节片前缘之前就终止分布的卵黄滤泡。格雷厄姆五叶槽绦虫新种是该类群中最大的成员，节片数量最多。基于头节形态的显著相似性，有人推测五叶槽绦虫属和合叶槽绦虫属属于“四叶目”中一个独特的亚群，暂定为分支1。基于首次为合叶槽绦虫属物种生成的28S rDNA基因D1 - D3区域的序列数据，我们确认了这两个属的相互单系性以及分支1的单系性，及其作为“四叶目”中一个独特谱系的地位。这项研究还表明，鉴于在这两个属的成员中都发现了五个面叶孔这一特征状态，所以五个面叶孔的存在是同功的。这些新物种将分支1的宿主关联范围扩大到包括其他鳐鱼和地毯鲨属。展望未来，我们预计会发现该类群的其他成员寄生于其他副须鲨科地毯鲨物种以及长吻鳐属的其他物种和无吻鳐科的长吻鳐属物种。在这里，我们将被称为分支1的分类单元中已描述物种的数量增加了一倍，同时也拓展了我们对其成员形态和解剖结构的理解。这些额外信息将有助于为绦虫目分类的最终修订提供参考，以解决当前“四叶目”这一分类阶元高度多系的问题。
