Caira Janine N, Jensen Kirsten
Department of Ecology & Evolutionary Biology, 75 N. Eagleville Rd., University of Connecticut, Storrs, Connecticut 06269-3043.
J Parasitol. 2014 Aug;100(4):373-91. doi: 10.1645/14-516.1. Epub 2014 May 20.
This review brings together decades of work on elasmobranch tapeworms. The field has advanced significantly over the past 20 yr, with an emphasis on the discovery and description of novel taxa, and the establishment of phylogenetic frameworks for individual orders and their interrelationships. Tapeworms parasitizing elasmobranchs represent 9 orders and include 977 species and 201 genera-over 250 species and 50 genera are new within the last 2 decades. The 9 orders are treated individually, highlighting recent assessments of phylogenetic relationships informed by molecular sequence data. All but the "Tetraphyllidea" are monophyletic. Although much remains to be learned about their interrelationships, existing phylogenetic hypotheses suggest that elasmobranch tapeworms have played a key role in the evolution of the cestodes of essentially all other vertebrate groups. The apical organ is a defining feature (i.e., a synapomorphy) of a clade consisting of acetabulate taxa and Litobothriidea. Novel hook amino acid composition data support the independent origin of hooks in the various groups of hooked tapeworms. Cestode records exist for representatives of most of the major groups of elasmobranchs, however skates (Rajiformes) and catsharks ("Scyliorhinidae") are particularly neglected in terms of species sampled. The majority of tapeworm species are extremely host-specific exhibiting species-specific (i.e., oioxenous) associations with their hosts. Rapid advancements in elasmobranch taxonomy, with over 300 of the 1,200 species appearing new in the past 20 yr, signal the need for careful attention to be paid to host identifications; such identifications are best documented using a combination of specimen, photographic, and molecular data. Above the species level, many cestode taxa are restricted to host orders, families, or even genera. Documentation of these affiliations allows robust predictions to be made regarding the cestode faunas of unexplored elasmobranchs. Trypanorhynchs are the notable exceptions. Life cycles remain poorly known. Recent applications of molecular methods to larval identifications have reinvigorated this area of research. Tapeworms are more diverse in elasmobranchs of tropical and subtropical waters, but they occur globally not only at the poles and in deep waters, but also in freshwaters of South America and Southeast Asia. The cestode faunas of batoids are much more speciose and complex than those of sharks. The faunas of deeper water sharks are particularly depauperate. The tapeworms of elasmobranchs and their hosts are now among the most well documented host-parasite systems in existence. This system has not yet reached its potential as a resource for investigations of basic ecological and evolutionary principles.
本综述汇集了数十年来关于板鳃类绦虫的研究工作。在过去20年里，该领域取得了显著进展，重点在于新分类单元的发现与描述，以及为各个目及其相互关系建立系统发育框架。寄生于板鳃类的绦虫有9个目，包括977个物种和201个属，在过去20年中有超过250个物种和50个属是新发现的。对这9个目分别进行了论述，突出了基于分子序列数据对系统发育关系的最新评估。除了“四叶目”之外，其他所有目都是单系的。尽管关于它们的相互关系仍有许多有待了解之处，但现有的系统发育假说表明，板鳃类绦虫在基本上所有其他脊椎动物类群的绦虫进化中发挥了关键作用。顶器是由具吸铗类分类单元和叶槽目组成的一个分支的决定性特征（即共衍征）。新的钩氨基酸组成数据支持了各种带钩绦虫类群中钩的独立起源。大多数主要板鳃类群的代表都有绦虫记录，然而，在采样物种方面，鳐（鳐形目）和猫鲨（“猫鲨科”）尤其被忽视。大多数绦虫物种具有极强的宿主特异性，与宿主呈现物种特异性（即单宿主性）关联。板鳃类分类学的快速发展，在过去20年里1200个物种中有超过300个是新发现的，这表明需要谨慎关注宿主鉴定；最好使用标本、照片和分子数据相结合的方式对这些鉴定进行记录。在物种水平之上，许多绦虫分类单元局限于宿主目、科甚至属。对这些关联的记录有助于对未探索板鳃类的绦虫动物区系做出可靠预测。锥吻绦虫是显著的例外。其生活史仍然鲜为人知。分子方法在幼虫鉴定中的最新应用为该研究领域注入了新活力。绦虫在热带和亚热带水域的板鳃类中更为多样，但它们遍布全球，不仅在极地和深水中存在，在南美洲和东南亚的淡水中也有发现。鳐目的绦虫动物区系比鲨目的更加多样和复杂。深水鲨的动物区系尤其贫乏。板鳃类及其宿主的绦虫现在是现存记录最完善的宿主 - 寄生虫系统之一。作为研究基本生态和进化原理的资源，这个系统尚未发挥出其潜力。
