Université de Caen Basse-Normandie, Algobank-Caen, IFR 146, 14032 Caen, France.
Protist. 2011 Nov;162(5):738-61. doi: 10.1016/j.protis.2011.05.001. Epub 2011 Jun 28.
The Pavlovophyceae (Haptophyta) contains four genera (Pavlova, Diacronema, Exanthemachrysis and Rebecca) and only thirteen characterised species, several of which are important in ecological and economic contexts. We have constructed molecular phylogenies inferred from sequencing of ribosomal gene markers with comprehensive coverage of the described diversity, using type strains when available, together with additional cultured strains. The morphology and ultrastructure of 12 of the described species was also re-examined and the pigment signatures of many culture strains were determined. The molecular analysis revealed that sequences of all described species differed, although those of Pavlova gyrans and P. pinguis were nearly identical, these potentially forming a single cryptic species complex. Four well-delineated genetic clades were identified, one of which included species of both Pavlova and Diacronema. Unique combinations of morphological/ultrastructural characters were identified for each of these clades. The ancestral pigment signature of the Pavlovophyceae consisted of a basic set of pigments plus MV chl cPAV, the latter being entirely absent in the Pavlova + Diacronema clade and supplemented by DV chl cPAV in part of the Exanthemachrysis clade. Based on this combination of characters, we propose a taxonomic revision of the class, with transfer of several Pavlova species to an emended Diacronema genus. The evolution of the class is discussed in the context of the phylogenetic reconstruction presented.
Pavlovophyceae（甲藻门）包含四个属（Pavlova、Diacronema、Exanthemachrysis 和 Rebecca）和仅十三个特征种，其中一些在生态和经济方面很重要。我们构建了基于核糖体基因标记测序的分子系统发育关系，涵盖了已描述的多样性，当有模式菌株时使用模式菌株，同时还使用了其他培养菌株。我们还重新检查了 12 个已描述物种的形态和超微结构，并确定了许多培养菌株的色素特征。分子分析表明，所有已描述物种的序列都不同，尽管 Pavlova gyrans 和 P. pinguis 的序列几乎相同，这可能形成了一个单一的隐种复合体。鉴定出了四个明确界定的遗传分支，其中一个分支包括 Pavlova 和 Diacronema 的物种。这些分支都有独特的形态/超微结构特征组合。Pavlovophyceae 的祖先色素特征由一套基本的色素加上 MV chl cPAV 组成，后者在 Pavlova + Diacronema 分支中完全缺失，而在部分 Exanthemachrysis 分支中由 DV chl cPAV 补充。基于这些特征的组合，我们提出了对该类群的分类修订，将几个 Pavlova 物种转移到一个修正的 Diacronema 属中。在提出的系统发育重建背景下，讨论了该类群的进化。
