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

Diversity and distribution Patterns of the infralittoral green macroalgae from Potiguar basin, Rio Grande do Norte, Northeastern Brazil

Diversity and distribution pattern of the infralittoral green macroalgae at Potiguar basin, Rio Grande do Norte, Northeastern Brazil were analyzed from material collected at depths varying from 2 to 100 m. Collections were carried out with two types of dredges during four campaigns: July 2002, May and November 2003 and May 2004 at 43 stations. Chlorophyta is represented by 54 species, five varieties and three forms. The most representative family is Caulerpaceae, and the most diverse genus is Caulerpa, with 11 species. The results showed that most taxa (89%) are rare, and 10% are present at low frequencies. The most frequent species was Caulerpaprolifera (Forssk.) J.V. Lamour. occurring at almost all coastal and inner shelf stations, recorded in all campaigns. Species distribution by depth range showed that higher species number occurred on the inner shelf from 10 to 20 m, and a wide vertical distribution pattern was registered for Anadyomenestellata (Wulfen in Jacq.) C. Agardh,Chamaedoris peniculum (J. Ellis & Solander) Kuntze, Codium isthmocladum Vickers, Microdictyon sp., Udoteaoccidentalis A. Gepp & E. Gepp and Ventricaria ventricosa (J. Agardh) J.L. Olsen & J.A. West. Four species, Cladophoracoelothrix Kütz., C.ordinata (Børgensen) C. Hoek, Caulerpellaambigua (Okamura) Prud'homme & Lokhorst and Halimedasimulans M. Howe, were recorded for the first time in Rio Grande do Norte