Botanica Marina

The phenolic fingerprint of the leaves ofPosidonia oceanicacollected from four different Mediterranean Sea regions was determined using a panel of analytical techniques. It was found to be dominated by caffeic tartrates, along with low amounts of coumaric and ferulic tartrates. Chicoric acid (CA) was unambiguously identified as the major phenolic compound, regardless of the sample or collection site. Caftaric acid (CAF) was the second most abundant phenolic, but in much lower average concentrations. These results contrast with most of the previous works, in which CA was not even mentioned. The dramatic influence of extract handling, as well as the importance of choosing the adequate criteria of identity to standards, was demonstrated. These results show the importance of analyzing the crude extract to avoid some of the major pitfalls in determining the phenolic fingerprints. This is the first report to identify and quantify CAF in the Posidoniaceae and to identify CA as the dominant phenolic inPosidonialeaves. The large accumulation of CA in both living (10.12–12.78 mg g^-1dw) and detrital leaves (2.49–12.11 mg g^-1dw) across large geographical scales is noteworthy. The lack of significant concentrations of flavonoids contrasts with other seagrass genera. Importantly, the phenolic signature ofP. oceanicashows significant similarities to those ofCymodocea nodosaandSyringodium filiforme, both belonging to the Cymodoceaceae. These results are discussed in terms of metabolic pathways and phylogenetic relationships.

Detrital and fresh specimens of the seagrass Cymodocea nodosa (Cymodoceaceae) from the Atlantic Ocean and Mediterranean Sea were screened for their phenolic content. For the first time, the major polyphenol was identified as chicoric acid (CA) by means of nuclear magnetic resonance, ultraviolet spectra, liquid chromatography/mass spectrometry, and comparison with standards. The CA content of the crude extracts was determined by quantitative high-performance liquid chromatography. The values found in the leaves ranged from 8.13 to 27.44 mg g^-1 dw. The concentration was smaller in the rhizomes, with 0.31–3.70 mg g^-1 dw. The phenolic profile was found to be similar whatever the geographical location in the Atlantic Ocean or the Mediterranean Sea. Considering the demonstrated therapeutic applications of CA, its high value on the nutraceutical market, and its rare occurrence in the plant kingdom, the high content found in C. nodosa detrital leaves makes this abundant biomass of interest for dietary and pharmaceutical applications.

Hypnea is a monophyletic genus with a complex nomenclatural and taxonomic history, and is an important commercial source of carrageenan. Phylogenies of this genus have been accessed based primarily on Asian species; however, recent studies performed in South America revealed a great diversity of species, for which phylogenetic relationships need to be evaluated. Three infrageneric sections are recognized in the genus: Pulvinatae, Spinuligerae, and Virgatae; however, morphological and molecular circumscriptions within each section lack clarity. In this study, we analyzed three distinct markers to establish phylogenetic relationships among Hypnea species. To assign each species to the correct section, morphological data were obtained from original descriptions, reference literature, and comparisons with type/topotype and herbaria specimens. Our analyses recovered robust phylogenies for the genus and provided new insights on the taxonomic status and relationships among and within Hypnea species. The combination of three genetic markers increased the resolution and support, resulting in the largest and best-resolved phylogeny of the genus to date. Single and combined analyses revealed that the three sections of the genus Hypnea are taxonomically irrelevant, as currently recognized. Morphological differences are not associated with monophyletic groups and similarities among clades could be better explained by convergent evolution in thallus habit.

We used three molecular markers (COI-5P, rbcL and UPA) to investigate the diversity of Hypnea spp., an economically important red algal genus, collected from India. Our concatenated tree (COI-5P and rbcL) supported the monophyly of two new species, Hypnea indica sp. nov. and Hypnea bullata sp. nov. H. indica diverged from its closest two sister species, Hypnea cervicornis and Hypnea tenuis (by 15.9 and 11.2%, respectively, in COI-5P; and 3.4 and 3.2% in rbcL). We describe H. indica as a new species characterised by an erect, percurrent main axis with spine-like branchlets in acute angles, straight and forked apices, axial cells surrounded by large periaxial cells or two cells similar in size to the axial cell, and the presence of lenticular thickening in the cross-section of the thallus. H. bullata diverged from its closest sister species, Hypnea brasiliensis (by 10.9% in COI-5P and 3.3% in rbcL). H. bullata is characterized by a prostrate thallus up to 1.5 cm in height, highly anastomosed, with an axial cell surrounded by similar sized, or smaller, periaxial cells, tetrasporangia present near the base of branchlets, and the presence of lenticular thickening.