Portal de Periódicos da CAPES

Telonemia, a new protist phylum with affinity to chromist lineages

2006; Royal Society; Volume: 273; Issue: 1595 Linguagem: Inglês

10.1098/rspb.2006.3515

1471-2954

Kamran Shalchian‐Tabrizi, Wenche Eikrem, Dag Klaveness, Daniel Vaulot, Marianne A. Minge, Florence Le Gall, Khadidja Romari, Jahn Throndsen, Andreas Botnen, Ramón Massana, Helge Abildhauge Thomsen, Kjetill S. Jakobsen,

Marine and coastal ecosystems

Recent molecular investigations of marine samples taken from different environments, including tropical, temperate and polar areas, as well as deep thermal vents, have revealed an unexpectedly high diversity of protists, some of them forming deep-branching clades within important lineages, such as the alveolates and heterokonts. Using the same approach on coastal samples, we have identified a novel group of protist small subunit (SSU) rDNA sequences that do not correspond to any phylogenetic group previously identified. Comparison with other sequences obtained from cultures of heterotrophic protists showed that the environmental sequences grouped together with Telonema, a genus known since 1913 but of uncertain taxonomic affinity. Phylogenetic analyses using four genes (SSU, Hsp90, alpha-tubulin and beta-tubulin), and accounting for gamma- and covarion-distributed substitution rates, revealed Telonema as a distinct group of species branching off close to chromist lineages. Consistent with these gene trees, Telonema possesses ultrastructures revealing both the distinctness of the group and the evolutionary affinity to chromist groups. Altogether, the data suggest that Telonema constitutes a new eukaryotic phylum, here defined as Telonemia, possibly representing a key clade for the understanding of the early evolution of bikont protist groups, such as the proposed chromalveolate supergroup.