The Cyathocotylidae is a globally distributed family of digeneans parasitic as adults in fish, reptiles, birds and mammals in both freshwater and marine environments. Molecular phylogenetic analysis of interrelationships among cyathocotylids is lacking with only a few species included in previous studies. We used sequences of the nuclear 28S rRNA gene to examine phylogenetic affinities of 11 newly sequenced taxa of cyathocotylids and the closely related family Brauninidae collected from fish, reptiles, birds and dolphins from Australia, Southeast Asia, Europe, North America and South America. This is the first study to provide sequence data from adult cyathocotylids parasitic in fish and reptiles. Our analyses demonstrated that the members of the genus Braunina (family Brauninidae) belong to the Cyathocotylidae, placing the Brauninidae into synonymy with the Cyathocotylidae. In addition, our DNA sequences supported the presence of a second species in the currently monotypic Braunina. Our phylogeny revealed that Cyathocotyle spp. from crocodilians belong to a separate genus (Suchocyathocotyle, previously proposed as a subgenus) and subfamily (Suchocyathocotylinae subfam. n.). Morphological study of Gogatea serpentum indicum supported its elevation to species as Gogatea mehri. The phylogeny did not support Holostephanoides within the subfamily Cyathocotylinae; instead, Holostephanoides formed a strongly supported clade with members of the subfamily Szidatiinae (Gogatea and Neogogatea). Therefore, we transfer Holostephanoides into the Szidatiinae. DNA sequence data revealed the potential presence of cryptic species reported under the name Mesostephanus microbursa. Our phylogeny indicated at least two major host switching events in the evolutionary history of the subfamily Szidatiinae which likely resulted in the transition of these parasites from birds to fish and snakes. Likewise, the transition to dolphins by Braunina represents another major host switching event among the Cyathocotylidae. In addition, our phylogeny revealed more than a single transition between freshwater and marine environments demonstrated in our dataset by Braunina and some Mesostephanus.

中文翻译：

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Cyathocotylidae（Digenea，Diplostomoidea）的分子系统发育需要系统性变化，并揭示宿主和环境转换的历史

Cyathocotylidae 是全球分布的 digeneans 家族，成年后寄生在淡水和海洋环境中的鱼类、爬行动物、鸟类和哺乳动物中。由于先前的研究中仅包含少数物种，因此缺乏对胞质体之间相互关系的分子系统发育分析。我们使用核 28S rRNA 基因的序列来检查从澳大利亚、东南亚、欧洲、北美洲和南美洲的鱼类、爬行动物、鸟类和海豚中收集的 cyathocotylids 和密切相关的 Brauninidae 科的 11 个新测序分类群的系统发育亲和力。这是第一项提供寄生于鱼类和爬行动物的成年细胞胚轴的序列数据的研究。我们的分析表明 Braunina 属（Brauninidae 科）的成员属于 Cyathocotylidae，将 Brauninidae 变成 Cyathocotylidae 的同义词。此外，我们的 DNA 序列支持目前单型 Braunina 中存在第二个物种。我们的系统发育表明 Cyathocotyle spp。来自鳄鱼的鳄鱼属于一个单独的属（Suchocyathocotyle，以前提出作为亚属）和亚科（Suchocyathocotylinae subfam. n.）。Gogatea serpentum indicum 的形态学研究支持将其提升为 Gogatea mehri 物种。系统发育不支持 Cyathocotylinae 亚科中的 Holostephanoides；相反，Holostephanoides 与 Szidatiinae 亚科（Gogatea 和 Neogogatea）的成员形成了一个强烈支持的进化枝。因此，我们将 Holostephanoides 转移到 Szidatiinae 中。DNA 序列数据揭示了以 Mesostephanus microbursa 为名报道的隐性物种的潜在存在。我们的系统发育表明在 Szidatiinae 亚科的进化历史中至少有两个主要的宿主转换事件，这可能导致这些寄生虫从鸟类过渡到鱼和蛇。同样，Braunina 向海豚的过渡代表了 Cyathocotylidae 中另一个主要的宿主转换事件。此外，我们的系统发育揭示了在我们的数据集中由 Braunina 和一些 Mesostephanus 证明的淡水和海洋环境之间的不止一个单一的过渡。Braunina 向海豚的过渡代表了 Cyathocotylidae 中另一个主要的宿主转换事件。此外，我们的系统发育揭示了在我们的数据集中由 Braunina 和一些 Mesostephanus 证明的淡水和海洋环境之间的不止一个单一的过渡。Braunina 向海豚的过渡代表了 Cyathocotylidae 中另一个主要的宿主转换事件。此外，我们的系统发育揭示了在我们的数据集中由 Braunina 和一些 Mesostephanus 证明的淡水和海洋环境之间的不止一个单一的过渡。