Volume 55, Issue 4

Only two species of Polysiphonia sensu lato (predominately species of Polysiphonia and Neosiphonia ) have been reported from Caribbean Panama. In contrast, 16 species are documented from the neighboring countries of Costa Rica and Colombia. Molecular-assisted identification using plastid-encoded ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene ( rbc L) and mitochondria-encoded cytochrome c oxidase subunit I gene (COI) loci identified 14 species from 38 samples collected along the Caribbean coast of Panama. Morphological character states were examined and used to identify each sample, and phylogenetic relationships among these species were estimated through maximum likelihood analyses of rbc L and nuclear-encoded SSU sequence data. Neosiphonia ferulaceae , N. tongatensis , Polysiphonia binneyi , P. havanensis , P. macrocarpa , P. pseudovillum , P. schneideri , P. subtilissima , and two species that could only be identified as P. cf. sertularioides are reported for the first time from Panama. Polysiphonia pentamera , a species only known from the eastern Pacific is reported for the first time in the Caribbean, and two new species, P. lobophoralis and P. nuda are described. A key to Caribbean Panama species, descriptions of species morphology and remarks on taxonomy and relationships are provided. These findings demonstrate that previous limited reports of Polysiphonia sensu lato species from Panama resulted from a lack of study, rather than a lack of diversity, within the region.

Currently, five genera are assigned to red seaweeds of the Laurencia complex worldwide: Chondrophycus , Laurencia s.s. , Osmundea , Palisada and Yuzurua . The genera are segregated on the basis of morphological characters, especially the reproductive traits, and molecular sequences of the plastid-encoded gene rbc L. Four of the genera have been resolved as monophyletic, but not Laurencia s.s. In this study based on an rbc L gene phylogeny we show the presence of a sixth lineage within the Laurencia complex, viz., Laurencia marilzae plus two unidentified species of Laurencia from Brazil. The phylogenetic position of this group, combined with the high genetic divergence from Laurencia s.s. (8.2–11%), strongly support the establishment of a sixth genus for the complex, proposed here as Laurenciella gen. nov. This new taxon differs from Laurencia s.s. and from the other genera of the complex by molecular sequence data, but is indistinguishable from Laurencia s.s. by the usual morphological features.

Approximately 29 species of Neosiphonia are currently recognized worldwide. We describe our unidentified samples collected from the Pacific coast of South America as a new species, N. peruviensis sp. nov., based on morphological and molecular data. Neosiphonia peruviensis sp. nov. is characterized by erect and prostrate thalli, rhizoids cut off from proximal ends of pericentral cells by cross walls, six pericentral cells that are totally ecorticate, abundant trichoblasts forked once or twice, prominent scar cells and tetrasporangia spirally arranged. Our new species is similar to several Neosiphonia / Polysiphonia species having more than four pericentral cells: N. notoensis , N. porrecta , “N. tepida” , N. teradomariensis, and “P. forfex” . However, N. peruviensis sp. nov. is distinguished from these similar species by having six pericentral cells through all of the thallus. Phylogenetic analyses of rbc L indicate that our N. peruviensis is placed in genus Neosiphonia and is also distinguishable from other Neosiphonia species.

The taxonomic distinctiveness and distribution of the brown alga Colpomenia durvillei are debatable; the species was first described from central Chile. We analyzed mitochondrial cox 3 and plastid rbc L sequences from specimens collected in central Chile and Sonora, Mexico, in combination with morphological observations of specimens collected in Chile, Peru, and Mexico. Compared with other elongate species of the genus, C. durvillei is distinguished by erect, elongate thalli arising from a wide colpomenioid base, up to eight layers of cortical and medullary cells, and plurilocular sporangia with many layers (up to 18 locules). In all phylogenetic analyses of cox 3 and rbc L sequences, all elongate species of the genus formed a clade, in which C. durvillei was consistently distinct from congeners. Colpomenia bullosa was closely related to C. durvillei in our cox 3 analyses, and the clade containing these two species was closely related to Colpomenia phaeodactyla. This is the first report to confirm C. durvillei by molecular data and also the first report on the occurrence of the species in Sonora, Mexico. It had previously been misidentified as a variant of C. phaeodactyla on the Pacific coast of South America, and the name C. durvillei was misapplied to C. bullosa in New Zealand.

Phymatolithon lamii (Hapalidiaceae, Corallinales, Rhodophyta) is reported for the first time in the Mediterranean Sea. A morphological-anatomical account of Gulf of Trieste specimens is presented along with comparisons with P. lamii specimens from other regions, comparisons with other Mediterranean species of Phymatolithon and a dichotomous key to known Mediterranean species of Phymatolithon . Whether P. lamii occurs naturally in the Mediterranean Sea but was previously misidentified as P. lenormandii or is, alternatively, an alien species, or both, has not been resolved.

We investigated phytobenthos in submerged marine caves. Underwater caves have rarely been examined for floristic composition. The study was carried out in two Mediterranean marine protected areas (MPAs) [Plemmirio (Maddalena Peninsula, Syracuse, Ionian Sea) and Pelagean Islands (Straits of Sicily)] and the caves were chosen on the basis of their geomorphology, exposure, and bathymetry. From our comparative study of cave floras, we demonstrated that the macroalgal flora of each cave is influenced by the floristic composition of the adjacent area that is a natural source of recruits and by the light environment. Caves that are “visited” (i.e., those situated on one of the underwater routes for scuba divers visiting the MPAs) had floristic richnesses higher than those of “scarcely” or “not visited” ones (i.e., not on tourist routed). This is likely because the visited caves, due to their large entrance and shallow location, have good lighting that favors high macroalgal biodiversity.

We surveyed macroalgae at Hansneset, Blomstrand (78°39′N, 11°57′E) in Kongsfjorden, Svalbard, down to 30 m depth between 1996 and 1998. In total, 62 species were identified: 16 Chlorophyta, 25 Phaeophyceae, and 21 Rhodophyta. The majority of species (53.5%) belonged to the Arctic cold-temperate group, followed in frequency by species distributed from the Arctic to the warm-temperate region (25.9%). Four endemic Arctic species ( Laminaria solidungula , Acrosiphonia flagellata , A. incurva , and Urospora elongata ) were found. Two species ( Pogotrichum filiforme and Mikrosyphar polysiphoniae ) were new to Svalbard. Chlorophyta, Phaeophyceae, and Rhodophyta extended from the eulittoral zone down to 11, 21, and >30 m depths with maximum biomasses at 1–5 m, 5–10 m, and 5–30 m depths, respectively. Annual and pseudoperennial species had highest biomasses in the upper 5 m, while perennials were distributed deeper. The highest biomass (8600 g m -2 wet weight) at 5 m depth comprised mainly L. digitata , Saccorhiza dermatodea , Alaria esculenta , and Saccharina latissima . The biogeographic composition of macroalgae at Hansneset was rather similar to that of northeastern Greenland, but different from that of northern Norway, which has a higher proportion of temperate species. Climate warming and ship traffic may extend some of the distribution ranges of macroalgae from mainland Norway to Svalbard.

Ongoing phytoplankton monitoring programs over the last 12 years in the northern Adriatic Sea showed that the diatom genus Bacteriastrum is an important component of the pelagic diatom assemblage. The main goals of this study were to identify which Bacteriastrum species occur in the northern Adriatic Sea and describe their distributions. Bacteriastrum comosum and B. hyalinum f. princeps were rare, while B. delicatulum , B. hyalinum , and B. mediterraneum were frequently present, together with the newly proposed species B. jadranum , described herein. This new species is weakly silicified and is mainly characterized by a large aperture between each cell of the filament. Cells are connected to each other by 8–12 setae, which cross at a distance equivalent to the diameters of 2–3 cells. There is no difference in the orientation of the setae on the two terminal cells, hence the species is placed in the section Isomorpha . The new species was recorded throughout the study area, in both coastal and offshore waters, with higher cell abundances in the vicinity of the Po River during the September–October period. The maximum cell abundance of B. jadranum was 244.2×10 3 cells l -1 in the surface waters at 44.75666667ºN, 12.75ºE in September 2006, sometimes representing up to 46% of the entire phytoplankton assemblage, as recorded in the surface waters at 45.06833333ºN, 13.515ºE in October 2008.

To characterize the structure and function of the protein phosphatase 2C (PP2C) gene in Porphyra yezoensis , full-length cDNA of the locus (denoted pypp2c ) was obtained by electronic cloning, rapid amplification of cDNA ends, and reverse-transcription PCR. The nucleotide sequence of PyPP2C was 1988 bp, including a 5′-untranslated region (UTR) of 301 bp, a 3′-UTR of 256 bp, and an open reading frame of 1431 bp that can be translated into 476 amino acids with a molecular mass of 50.96 kDa and a putative isoelectric point of 8.34. The amino acids had 30–36% identity with those encoded by PP2C genes in protozoa and higher plants. A PP2C-like catalytic domain was found in the 57–397 region, and several residues involved in the metal ion binding sites were conserved. mRNA expression levels in the three life stages of leafy thalli, filaments, and conchospores were examined by real-time fluorescent quantitative PCR. Highest expression of pypp2c occurred in conchospores. Gene expression levels were similar among the three life stages. pypp2c expression at different thallus relative water contents (RWCs) varied, with the highest expression occurring at 60% RWC.

Endophytic fungi isolated from the red seaweed Bostrychia radicans were studied to identify their molecularly diverse and biologically active natural chemical products. According to 28S ribosomal DNA-based identification, the strain named C81 was 98% identical to Phomopsis longicolla . This strain was cultivated in solid rice medium and produced three major metabolites identified as 18-deoxycytochalasin H ( 1 ), mycophenolic acid ( 2 ), and dicerandrol C ( 3 ). The chemical structures of these compounds were elucidated by 1D and 2D nuclear magnetic resonance as well as by mass spectrometry. Dicerandrol C had significant antimicrobial activity against Staphylococcus aureus (ATCC 6538) and Staphylococcus saprophyticus (ATCC 15305), with minimum inhibitory concentrations of 1 and 2 μg ml -1 (1.33 and 2.66 μ m ), respectively. These results show the presence of promising metabolites and indicate that these natural products should be considered in the development of new antibiotics.

We report fertile gametophytes of Polysiphonia perforans for the first time in collections from the Mediterranean Sea. The occurrence of spermatangial axes replacing whole trichoblasts and four-celled carpogonial branches, in addition to the previously known features, such as the occurrence of four pericentral cells, the open connection between rhizoids and pericentral cells and the straight arrangement of tetrasporangia, allow us to confirm that the species belongs to the genus Polysiphonia .