Ifremer, LER BO, Station de Biologie Marine, Place de la Croix, BP40537, F-29185 Concarneau Cedex, France.
Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan.
Harmful Algae. 2020 Sep;98:101902. doi: 10.1016/j.hal.2020.101902. Epub 2020 Sep 18.
A recently published study analyzed the phylogenetic relationship between the genera Centrodinium and Alexandrium, confirming an earlier publication showing the genus Alexandrium as paraphyletic. This most recent manuscript retained the genus Alexandrium, introduced a new genus Episemicolon, resurrected two genera, Gessnerium and Protogonyaulax, and stated that: "The polyphyly [sic] of Alexandrium is solved with the split into four genera". However, these reintroduced taxa were not based on monophyletic groups. Therefore this work, if accepted, would result in replacing a single paraphyletic taxon with several non-monophyletic ones. The morphological data presented for genus characterization also do not convincingly support taxa delimitations. The combination of weak molecular phylogenetics and the lack of diagnostic traits (i.e., autapomorphies) render the applicability of the concept of limited use. The proposal to split the genus Alexandrium on the basis of our current knowledge is rejected herein. The aim here is not to present an alternative analysis and revision, but to maintain Alexandrium. A better constructed and more phylogenetically accurate revision can and should wait until more complete evidence becomes available and there is a strong reason to revise the genus Alexandrium. The reasons are explained in detail by a review of the available molecular and morphological data for species of the genera Alexandrium and Centrodinium. In addition, cyst morphology and chemotaxonomy are discussed, and the need for integrative taxonomy is highlighted.
最近发表的一项研究分析了 Centrodinium 和 Alexandrium 属之间的系统发育关系，证实了早期的一项研究表明 Alexandrium 属是并系的。这篇最新的论文保留了 Alexandrium 属，引入了一个新的属 Episemicolon，复活了两个属 Gessnerium 和 Protogonyaulax，并指出：“Alexandrium 的多系性通过分为四个属得到解决”。然而，这些重新引入的分类群不是基于单系群。因此，如果被接受，这项工作将导致用几个非单系群取代一个并系群。用于属特征描述的形态数据也没有令人信服地支持分类群的划分。分子系统发育学的薄弱和缺乏诊断特征（即独特特征）使得有限概念的适用性有限。本文拒绝基于现有知识将 Alexandrium 属分裂。目的不是提出替代分析和修订，而是保留 Alexandrium。一个更好构建和更系统发育准确的修订可以而且应该等到更完整的证据出现，并强烈需要修订 Alexandrium 属。通过对 Alexandrium 和 Centrodinium 属的物种的可用分子和形态数据的回顾，详细解释了这些原因。此外，还讨论了胞囊形态和化学分类学，并强调了综合分类学的必要性。
