A morphological and molecular study of austral sargassum (fucales, phaeophyceae) supports the recognition of phyllotricha at genus level, with further additions to the genus sargassopsis

Sargassum subgenus Phyllotricha currently includes seven species restricted to Australian and New Zealand coasts. A recent study of Cystoseira and other Sargassaceae genera based on mitochondrial 23S DNA and chloroplast-encoded psbA sequences resulted in the most widely distributed species of subgenus Phyllotricha, Sargassum decurrens, being transferred to the reinstated monospecific Sargassopsis Trevisan. The fate of the residual six Phyllotricha species, however, was not considered. The present study examines these Phyllotricha species, alongside other Sargassum subgenera, Sargassopsis, Sirophysalis trinodis (formerly Cystoseira trinodis) and the New Zealand endemic Carpophyllum Greville, using morphological evidence and the molecular phylogenetic markers cox3, ITS-2 and the rbcL-S spacer. Our results suggest both the genus Sargassum and Sargassum subgenus Phyllotricha are polyphyletic as currently circumscribed. Four S. subgen. Phyllotricha species, i.e. S. sonderi, S. decipiens, S. varians and S. verruculosum, form a monophyletic group sister to the genus Carpophyllum, and S. peronii is genetically identical to S. decurrens with regard to all three loci. We propose the resurrection of the genus Phyllotricha Areschoug, with type species Phyllotricha sonderi, and include the new combinations Phyllotricha decipiens, Phyllotricha varians and Phyllotricha verruculosum. Sargassum peronii, S. heteromorphum and S. kendrickii are transferred to Sargassopsis and Sargassum peronii is considered a synonym of Sargassopsis decurrens

North meets south – Taxonomic and biogeographic implications of a phylogenetic assessment of Sargassum subgenera Arthrophycus and Bactrophycus (Fucales, Phaeophyceae)

The Sargassum subgenera Bactrophycus and Arthrophycus were considered to be geographically restricted to the northern and southern hemispheres, respectively. Phylogenetic analyses of 19 Sargassum subgenus Bactrophycus species and eight Sargassum subgenus Arthrophycus species, based on a concatenated dataset of the loci ITS-2, cox3 and the rbcL-S spacer, showed that they formed a single clade, with Arthrophycus species nested within Bactrophycus section Halochloa. We merged the two subgenera as subgenus Bactrophycus and transferred “Arthrophycus” species to Sargassum section Halochloa. The genus now includes only the two subgenera, Sargassum and Bactrophycus, and both were found at temperate and subtropical latitudes; only subgenus Sargassum occurred at low latitudes near the equator, whereas subgenus Bactrophycus had an antitropical, disjunct distribution

Molecular diversity of the Caulerpa racemosa-Caulerpa peltata complex (Caulerpaceae, Bryopsidales) in New Caledonia, with new Australasian records for C. racemosa var. cylindracea

Molecular characterization (plastid-encoded tufA gene) of New Caledonian members of the Caulerpa racemosa-Caulerpa peltata complex identified five lineages, each possibly harboring multiple species-level entities. On a global scale, the complex encompassed six lineages, two of which were pantropical and the remainder seemingly were restricted to the Judo-Pacific basin. Caulerpa racemosa var. cylindracea, a fast-spreading introduced taxon in the Mediterranean Sea and the Canary Islands, was previously thought to be restricted to southwestern Australia; it was newly reported here for New Caledonia and several northern Australian locations, including the Great Barrier Reef

Characterization and phylogenetic affinities of the red alga Chondrophycus flagelliferus (Rhodomelaceae, Ceramiales) from Brazil on the basis of morphological and molecular evidence

© 2006 International Phycological SocietyA detailed study of the vegetative and reproductive morphology of Chondrophycus flagelliferus from Brazil is provided. The species possesses axial segments, each bearing two periaxial cells, a situation characteristic for the genus Chondrophycus. Within Chondrophycus, C. flagelliferus belongs to the subgenus Palisadi, section Palisadi, on the basis of the presence of a palisade-like outer cortical cell layer as seen in transverse sections of branchlets; the absence of secondary pit connections between cortical cells; the fertile periaxial cell with two pre-sporangial cover cells, the tetrasporangium initial and the post-sporangial cover cell that will develop into the corticating system; and the right-angled tetrasporangial arrangement. The phylogenetic position of this species within Laurencia sensu lato is inferred from parsimony and Bayesian analyses of chloroplast-encoded rbcL sequences from 39 Rhodomelaceae using two Ceramiaceae as the out-group. This study corroborates the taxonomic decision to split Laurencia sensu lato in the genera Laurencia, Chondrophycus and Osmundea, and indicates that rbcL provides sufficient phylogenetic signal to infer species-level relationships within the Laurencia sensu lato complex. Synapomorphic morphological characters uniting Laurencia and Chondrophycus include the same origin of the spermatangial filaments and tetrasporangia. The principal character separating both genera is the number of periaxial cells per vegetative axial segment. We hypothesize that the ancestor of the Laurencia sensu lato complex most likely possessed two periaxial cells per axial segment. The molecular data indicate that C. flagelliferus is closely related to the C. papillosus complex, and that, as originally described, C. translucidus belongs in the genus Laurencia.Mutue T. Fujii, Silvia M.P.B. Guimaràes, Carlos Frederico D. Gurgel, and Suzanne Frederic