Integrative Taxonomy of the Pavlovophyceae (Haptophyta): A Reassessment

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...

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Bibliographic Details
Published in:Protist 2011-11, Vol.162 (5), p.738-761
Main Authors: Bendif, El Mahdi, Probert, Ian, Hervé, Annie, Billard, Chantal, Goux, Didier, Lelong, Christophe, Cadoret, Jean-Paul, Véron, Benoît
Format: Article
Language:English
Subjects:
18S rDNA
Diacronema
Environmental Sciences
Evolution, Molecular
Exanthemachrysis
genes
Haptophyta
Haptophyta - classification
Haptophyta - genetics
Haptophyta - isolation & purification
Haptophyta - ultrastructure
Life Sciences
Molecular Sequence Data
Pavlova
Pavlova gyrans
Pavlovophyceae
Phylogeny
pigments
Rebecca
taxonomic revisions
taxonomy
ultrastructure
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Summary: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.
ISSN:1434-4610
1618-0941
DOI:10.1016/j.protis.2011.05.001