Bibliographic Detail
Draisma, S.G.A., Ballesteros, E., Rousseau, F. & Thibaut, T., 2010
Reference:
Draisma, S.G.A., Ballesteros, E., Rousseau, F. & Thibaut, T. (2010). DNA sequence data demonstrate the polyphyly of the genus Cystoseira and other Sargassaceae genera (Phaeophyceae). Journal of Phycology 46(6): 1329-1345.
Abstract:
Phylogenetic relationships in the Sargassaceae
were explored using three DNA markers, and the
monophyly of its genera was challenged. Nineteen
out of 24 currently recognized genera were sampled,
representing 63 species. The variable mt23S-tRNA
Val intergenic spacer could only be aligned within
genera and could not be used to infer intergeneric
relationships. The partial mt23S was also useful to
delineate genera and was alignable at the family level
but provided few informative characters. Analysis of
mt23S DNA sequences together with chloroplast-encoded
psbA sequences resulted in a better resolved
phylogeny. Hormophysa was the first genus to branch
off within the Sargassaceae, followed by Myriodesma;
then the three genera Caulocystis, Carpoglossum, and
Scaberia in unresolved order; and then Acrocarpia.
The other taxa studied here were divided over
three major clades, but there was no branch support
for the monophyly of two of these. The genera
Bifurcaria, Cystoseira, Halidrys, and Sargassum
appeared polyphyletic. The following taxonomic
changes are proposed: a new genus Brassicophycus
for Bifurcaria brassicaeformis (Kützing) E. S. Barton;
reinstatement of the genus Sargassopsis for Sargassum
decurrens (R. Brown ex Turner) C. Agardh; reinstatement
of the genus Sirophysalis for Indo-Pacific
Cystoseira trinodis (Forsskål) C. Agardh; reinstatement
of the genus Polycladia for the western Indian Ocean
species Cystoseira indica (Thivy et Doshi) Mairh,
Cystoseira myrica (S. G. Gmelin) C. Agardh, and
Acystis heinii Schiffner; and reinstatement of the
genus Stephanocystis for the North Pacific Cystoseira
species and Halidrys dioica N. L. Gardner. The
European Cystoseira species should be split into three
genera, but no name changes are proposed yet,
because diagnostic characters were found only for
the clade including the type species. Some evolutionary
trends could be discerned from the mt23S + psbA
phylogeny.
