ABSTRACT The Gracilariaceae is a species-rich family, with a number of members having high commercial value as sources of agar. Members of this family are also known for their phenotypic plasticity and convergent morphologies, resulting in considerable taxonomic confusion. Over the past two decades, two species of Agarophyton (previously part of Gracilaria) have been recognised in New Zealand with very similar morphologies and growth habits, and they have been incorrectly grouped as Agarophyton chilense. Agarophyton chilense is distributed in Chile and New Zealand and is genetically distinct from Agarophyton sp. from Australia and New Zealand. We name this new species A. transtasmanicum sp. nov. Morphologically A. transtasmanicum has fewer medullary cell layers and a more abrupt transition in cell size between cortex and medulla than A. chilense. The cox1 and rbcL dataset grouped A. transtasmanicum as sister to A. tenuistipitatum with high support. Clarifying the distinctions between A. chilense and A. transtasmanicum will enable further research, including investigating differences in distribution patterns, physiology, ecology, and chemical composition of these two Agarophyton species.

中文翻译：

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Agarophyton transtasmanicum sp. 十一月 来自澳大利亚和新西兰

摘要 江蓠科是一个物种丰富的科，许多成员作为琼脂的来源具有很高的商业价值。该家族的成员也因其表型可塑性和趋同形态而闻名，导致相当大的分类混乱。在过去的二十年里，新西兰发现了两种具有非常相似的形态和生长习性的琼脂植物（以前是江蓠的一部分），它们被错误地归类为智利琼脂。Agarophyton chilense 分布于智利和新西兰，在遗传上与 Agarophyton sp. 不同。来自澳大利亚和新西兰。我们将这个新物种命名为 A. transtasmanicum sp。十一月 从形态上看，A. transtasmanicum 的髓质细胞层较少，皮质和髓质之间的细胞大小转变比 A. chilense 更突然。cox1 和 rbcL 数据集将 A. transtasmanicum 归为 A. tenuistipatum 的姐妹，支持率很高。澄清 A. chilense 和 A. transtasmanicum 之间的区别将有助于进一步研究，包括调查这两种琼脂植物物种在分布模式、生理学、生态学和化学成分方面的差异。