ABSTRACT Tydemania Weber-van Bosse is a genus belonging to the family Udoteaceae (Bryopsidales, Chlorophyta) and currently thought to be monospecific throughout its distribution range in the Indo-Pacific. We tested the assumption that Tydemania is a single species using species delimitation methods, morphological observations and phylogenetic reconstructions of large datasets. Our molecular and morphological data recovered two distinct groups, which we argue are the type species T. expeditionis Weber-van Bosse and T. gardineri A. Gepp & E. Gepp. The latter is currently considered a synonym of the former and we resurrect this name from synonymy. T. gardineri is distinguished morphologically from T. expeditionis by the complete absence of glomeruli, whereas T. expeditionis can have glomeruli and flabella, glomeruli alone, or flabella alone. The two species can also be distinguished by the shape and length of the stalks at the base of the flabellum, the diameter of the main axis and of the flabella siphons at the apices. In addition, they have different geographic distributions, with T. gardineri restricted to the Western Indian Ocean, and T. expeditionis extending from the Red Sea, throughout the Indian Ocean and into the West Pacific, including the Coral Triangle, the Philippines and Japan. From our dataset and literature search, we hypothesize that its south-western distribution limit is in northern Madagascar. Finally, we confirm the synonymization of T. mabahithae with T. expeditionis based on specimens from the type locality of the former and the lack of flabella in several other specimens of T. expeditionis.

中文翻译：

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一百年后，根据分子和形态学数据，Tydemania gardineri A. Gepp & E. Gepp（Udoteaceae，Chlorophyta）的复活

摘要 Tydemania Weber-van Bosse 是属于 Udoteaceae (Bryopsidales, Chlorophyta) 的一个属，目前被认为在其在印度-太平洋的整个分布范围内都是单种的。我们使用物种定界方法、形态观察和大型数据集的系统发育重建来测试 Tydemania 是单一物种的假设。我们的分子和形态数据恢复了两个不同的群体，我们认为它们是模式物种 T. expeditionis Weber-van Bosse 和 T. gardineri A. Gepp & E. Gepp。后者目前被认为是前者的同义词，我们从同义词中恢复了这个名称。T. gardineri 在形态学上与 T. expeditionis 的区别在于完全没有肾小球，而 T. expeditionis 可以有肾小球和 flabella、单独的肾小球或单独的 flabella。这两个物种也可以通过扇叶基部的茎的形状和长度、主轴的直径和顶端的扇叶虹吸管的直径来区分。此外，它们有不同的地理分布，T. gardineri 仅限于西印度洋，T. expeditionis 从红海延伸到整个印度洋并进入西太平洋，包括珊瑚三角区、菲律宾和日本。根据我们的数据集和文献搜索，我们假设它的西南分布限制在马达加斯加北部。最后，我们根据 T. mabahithae 与 T. expeditionis 的同义词，基于来自前者的类型产地的标本以及在其他几个 T. expeditionis 标本中缺乏扇叶。