Laurencia Complex Research Articles

Laurencia mediterranea sp. nov. (Ceramiales, Rhodophyta) from the central Mediterranean Sea

Abstract The identification of macroalgal species within the Laurencia complex is challenging, due to the presence of inconspicuous morphological characters, extensive variation in these traits and a diverse biogeography. Moreover, for a number of these species, no DNA sequence data are available in online databases. For this study, five algal specimens, tentatively assigned to Laurencia, were collected from Malta in the central Mediterranean Sea and studied using an integrative systematics approach. An analysis of the data resulted in the description of a new species, Laurencia mediterranea using combined morphological and molecular criteria, including COI-5P and rbcL. Morphologically L. mediterranea sp. nov. was distinct from other Laurencia spp. in the type of holdfast, the colour and shape of the thallus, the presence of secondary pit connections, lenticular thickenings and ‘corps en cerise’. Moreover, a new genetic species cluster indicated a separate taxon at the species level. Our study demonstrates that genetic sequences having clear links to sample metadata and digital herbaria are indispensable for macroalgal biodiversity research. This approach could offer a solution for algal taxonomy in cases where biogeography is important and limited sequence data exist in online DNA libraries.

Discovery of New Cytotoxic Aplaminone Derivatives from the Sea Hare Aplysia kurodai and Elucidation of Their Accumulation from Local Sea Algae through the Food Chain

AbstractThe shell‐less herbivorous marine mollusk (sea hare) Aplysia kurodai is known to contain a variety of bioactive substances. While these compounds have been thought to originate from sea algae or their associated microbes, most of their origin and acquisition pathways are still unclear. Six new cytotoxic aplaminone derivatives, bromodopamine‐terpenoid hybrid molecules, were isolated from A. kurodai. Among them, isoaplaminone had a reverse prenyl group at the C15 aliphatic chain, which is a rare structural feature from the viewpoint of terpenoid biosynthesis. Investigation for chemical components in A. kurodai and the sea algae collected at several different locations revealed that two major aplaminones were contained in the Laurencia complex species at specific sites. Our chemical and ecological studies provide new insights into the origin of marine alkaloid toxins and their dynamism through the food chain.

Molecular Analysis Resolves the Taxonomy of the Laurencia Complex (Rhodomelaceae, Ceramiales) in Bermuda and Uncovers Novel Species of Chondrophycus and Laurenciella

In the last decade, molecular tools have revealed a significant number of previously unrecognized taxa in Bermuda's marine flora, especially among the Rhodophyta. A number of species have been persistently misidentified based on morphological similarities to species described from other localities. Some have been assigned to existing taxa not previously reported for the islands, and many have been determined to be novel species. Of late, researchers have substantially modified the ‘Laurencia complex’ in several regions around the globe. Herein, we confirm the presence in Bermuda of five of the eight genera recognized in this complex – Laurencia J.V.Lamouroux, Chondrophycus (J.Tokida & Y.Saito) Garbary & J.T.Harper, Palisada (Yamada) K.W.Nam, Yuzurua (K.W.Nam) Martin-Lescanne and Laurenciella Cassano, Gil-Rodríguez, Senties, Díaz-Larrea, M.C.Oliveira & M.T.Fujii, and discuss the species historically and presently known in the islands. Both rbcL chloroplast sequences and COI-5P mitochondrial sequences support the recognition of at least two species for what has historically been labeled L. obtusa in Bermuda, these assigned to L. dendroidea J.Agardh and L. catarinensis Cordeiro-Marino & M.T.Fujii in molecular analyses. We present two new species, Chondrophycus planiparvus Popolizio, C.W.Schneider & C.E.Lane, sp. nov. and Laurenciella namii Popolizio, C.W.Schneider & C.E.Lane, sp. nov., the latter genetically distinct from L. marilzae (Gil-Rodriguez, Sentíes, Diaz-Larrea, Cassano & M.T.Fujii) Gil-Rodriguez, Sentíes, Diaz-Larrea, Cassano & M.T.Fujii, L. mayaimii Collado-Vides, Cassano & M.T.Fujii and an undescribed species from Brazil. We also used ITS (rRNA) sequences to explore species limits for Laurencia catarinensis, L. dendroidea and L. microcladia Kützing. A full description of Laurencia microcladia, based on recent collections from Bermuda and the Caribbean Sea, is also included in this study.

Codon Usage of Chloroplast Gene rbcL in Laurencia sensu lato (Rhodophyta) species

Recent advances in molecular biology make it possible to sequence not only genes or genomes, but also to understand codon dynamics. For the organelle genes of these organisms, a small set of preferred codons are used for encoding proteins. For the first time, this paper treats the divergence of synonymous codon usage and its bias in the rbcL gene within the Laurencia complex of red algae. We observed that the synonymous codon preference biases in rbcL are large and differ among species. A clear distinction in codon usage between genera is evident: the genera Dasya and Delesseria use a set that fluctuated between 53 and 58 codons. Whereas, in the genera Ceramium, Chondrophycus, Chlamydomonas, Chlorella, Laurencia s.s, Osmundea, and Palisada codon usage indicates a higher restriction fluctuating between 40 to 51 codons. Laurencia complex genera and other representative algae showed a defined composition pattern, with lower percentage values of NNC/G (7-24.9%). Dasya and Delesseria showed a selective pattern tendency because of high percentage values of NNC/G (54-55%). The estimated codon bias parameters were tested to infer systematic relationships and match suitable codons with the NNC / G codon percentages. Cluster analysis based on Codon Usage supports phylogenetic relationships between Chondrophycus, Palisada, Laurencia, Osmundea, and Yuzurua species.

Chondrophycus anabeliae and Laurencia digitata (Ceramiales, Rhodophyta) are recorded for the first time for Venezuela expanding their geographic distributions beyond the type localities

Background: Over the course of approximately 12 years, the species of the Laurencia complex have been systematically studied in the tropical and subtropical Atlantic Ocean, showing high diversity (48 species), which has been underestimated for the coast of Venezuela.
 Questions: What is the species diversity of the Laurencia complex in Venezuela?
 Studied species: Chondrophycus anabeliae , Laurencia digitata .
 Study site and dates: Cayo Muerto, Parque Nacional Morrocoy, Estado Falcón, Venezuela, 2015.
 Methods: For molecular studies, the plastid rbc L gene and the mitochondrial DNA barcode marker COI-5P were used, combined with the study of current morpho-anatomical characters used for the identification of the species of the complex.
 Results: The occurrence of Chondrophycus , as currently circumscribed, was confirmed for the first time for Venezuela. Chondrophycus anabeliae and Laurencia digitata are reported for the first time beyond the type localities. Tetrasporophytes are described for the first time for L. digitata .
 Conclusions: Our findings expand the geographic distribution of Ch. anabeliae and L. digitata for the Venezuelan Caribbean and the Atlantic Ocean, respectively.

Laurencia longiramea sp. nov. for Brazil and an emendation of the generic delineation of Corynecladia (Ceramiales, Rhodophyta)

ABSTRACTStudies of the Laurencia complex based on phylogenetic and DNA barcoding analyses revealed a new species, Laurencia longiramea Cassano, G.N. Santos, J.M.C. Nunes, M.C. Oliveira & M.T. Fujii sp. nov., on the Brazilian coast. The rbcL phylogenetic analysis resolved L. longiramea as sister to Laurencia species from the North Atlantic (L. pyramidalis, L. viridis and L. obtusa) and the Caribbean Sea and Gulf of Mexico (L. intricata), with a divergence of 2.4%–3.7%. Using the DNA barcode COI-5P, L. longiramea was closest to L. pacifica from the United States, with a divergence of 4.2%. The new species has the typical features of the genus Laurencia and is characterised by: sparse branching, axes smaller than 1 mm diameter, often long branchlets, lenticular thickenings always present and abundant, and absence of cortical cells projected near branch apices. Morphologically, L. longiramea is similar to Laurencia filiformis. However, an rbcL sequence of L. filiformis from the type locality (Western Australia) confirmed that they are distinct species, with 4.3% divergence. Examination of Laurencia clavata from Brazil, deposited in the University of São Paulo (SPF) herbarium, were misidentified and corresponded to the new species, L. longiramea. In addition, the rbcL and COI-5P sequences of L. clavata from the type locality (Australia) did not join with L. longiramea. Laurencia clavata formed a well-supported clade with the two species of Coronaphycus. Priority supported the recognition of Corynecladia over Coronaphycus, requiring the new combinations Corynecladia elata (C.Agardh) comb. nov. and Corynecladia nova (Metti) comb. nov. Based on our results, Corynecladia clavata does not occur in the Brazilian marine flora.

Molecular and morphological characterization of Laurencia intricata and Laurenciella mayaimii sp. nov. (Ceramiales, Rhodophyta) in South Florida, USA

:Morphological characterization, together with phylogenetic and DNA barcoding analyses on the basis of rbcL and COI-5P, conducted on some species of the Laurencia complex in South Florida confirmed the occurrence of Laurencia intricata and supported the presence and recognition of Laurenciella in the United States. Samples of L. intricata from Florida grouped with full support with the species from the type locality (Antilles). The intraspecific divergence within the L. intricata clade ranged from 0.0% to 1.3%; the samples from Florida diverged by only 0.06% to 0.20%, the sample from Mexico (EF658643 – Puerto Morelos, Quintana Roo) being the most divergent. The two new species of Laurenciella from Florida, La. mayaimii and La. sp., formed an assemblage with La. marilzae with full support, and the interspecific divergence was high for both molecular markers. Laurenciella mayaimii is characterized mainly by its brownish-yellow main axis and cylindrical, alternate to subopposite branchlets, anastomoses between branches in the basal portions, and a single ‘corps en cerise’ present in each cortical cell and in trichoblasts. In addition, the walls of the cortical cells near the apices project, and lenticular thickenings are absent. The finding of Laurenciella in Biscayne Bay and Key Largo, South Florida expands its geographic distribution to western Atlantic lower subtropical waters.

Phylogeography of the Red Algal Laurencia Complex in the Macaronesia Region and Nearby Coastal Areas: Recent Advances and Future Perspectives

Abstract: Since the conception of the genus Laurencia by Lamouroux in 1813, several red macroalgal species have been included in it. In recent decades, the development of modern molecular tools has resulted in multiple taxonomic modifications, and presently, eight related genera are recognized in the so-called Laurencia complex. In the Macaronesian Region (Central East Atlantic Ocean), species from the Laurencia complex are keystone elements of the benthic communities, especially in the intertidal zone. In this review, we consolidate the existing knowledge about the Laurencia complex within the Macaronesian archipelagos and nearby areas. Morphological descriptions and phylogeographic remarks of the 16 currently accepted species—whose records were molecular or morphologically confirmed—are included together with an identification key for the Macaronesian Region. The phylogeographic data allowed us to re-visit the role of the Macaronesian archipelagos as a bridge area for the marine flora of the Mediterranean and Caribbean Seas (remnants of the former Thetyan Sea) or contemplate their marine flora as the result of successive processes of recolonization after the Quaternary glaciations from those donor areas. Finally, some comments about the frontiers of the research in the Laurencia complex in the Macaronesian Region and nearby coastal areas are included.

Morpho-structural and ecological features of a shallow vermetid bioconstruction in the Tyrrhenian Sea (Mediterranean Sea, Italy)

Biogenic formations, built up by the sessile and gregarious vermetid gastropod Dendropoma cristatum, were studied from June to October 2014 along the rocky shores of Licosa islet (Gulf of Salerno, Tyrrhenian Sea), where they build up the northernmost reefs in the Mediterranean Sea in order to shed light on possible latitudinal changes. The islet has two differently exposed sides, with three types of vermetid formations: the first consists in a thin layer composed by vermetid gastropods and the coralline alga N. brassica-florida, widespread only in the sheltered side of the islet; the second is represented by small isolated pillows (13.9±5.64cm), all around the islet at depth of more than fifteen centimetres; the third is a well-structured reef, characterized by a dense layer of mollusc shells that overgrow each other, only found in the exposed side of the islet. The vermetid reef was monitored in two sites with different substrates: ancient walls, made of calcareous lateritious material, and the flysch rocks, composed by siliceous turbiditic deposits. While no differences arise in gastropod density related to rock type (calcareous lateritious material versus siliceous turbiditic deposits), significant differences have been found along a vertical gradient, seeing density increases from the upper intertidal to the upper subtidal level. The associated algal cover seems to be inversely related to the vermetid density. In the upper intertidal, D. cristatum was almost completely covered (about 83%) by a thick layer of encrusting alga N. brassica-florida. In the lower intertidal the encrusting alga disappear but the shells of vermetid gastropods were remarkably colonized by the erected red algae of the “Laurencia complex” (70%) while in the upper subtidal, the vermetid shells were scarcely covered, mainly by other algal species (13%). By comparing present data with those of Sicilian reefs no evidences arise due to the different latitude. Innovative approaches (Remotely Piloted Aircraft Systems technology and fractal geometry) applied to these marine bioconstructions, resulted very effective in mapping and structuring the complexity of the reefs.

Discrimination and Characterization of Two Mediterranean Species from the Laurencia Complex (Rhodomelacea) Using an NMR-Based Metabolomic Approach.

Generic and specific determination among the Laurencia complex is a challenging task. DNA barcoding combined with phenotypic investigations are mandatory for species differentiation. In this study, two morphologically different members of the Laurencia complex were investigated using untargeted 1 H-NMR-based metabolomics. Twenty-one population samples were collected in order to evaluate both temporal and geographical homogeneity. Data obtained from 1 H-NMR analysis followed by statistical analysis allowed a clear separation of all the samples into two groups. DNA mitochondrial tests confirmed this pattern and identified the two species as Laurenciella sp. and Laurencia obtusa. In addition, metabolites responsible of this discrimination were investigated directly in crude extracts by 13 C-NMR using an in-house computer-assisted method. The combination of both untargeted (1 H) and targeted (13 C) NMR-based metabolomic approaches proves to be a powerful and complementary approach to discriminate species from the Laurencia complex.

Seasonal recruitment and survival strategies of Palisada cervicornis comb. nov. (Ceramiales, Rhodophyta) in coral reefs.

As marine tropical ecosystems deteriorate and lose biodiversity, their communities are shifting to being dominated by a few species, altering ecosystem's functioning and services. Macroalgae are becoming dominant on coral reefs, and are frequently observed outcompeting corals. Turf algal assemblages are the base of energy flow in these systems and one of the most abundant types of macroalgae on coral reefs, but little is known about their biology and diversity. Through molecular and morphological analyses, we identified the turf-forming species Laurencia cervicornis, and by studying seasonal recruitment and the impact of herbivorous fishes on its abundance, we describe its survival strategy. The molecular analyses used a total of 45 rbcL gene sequences including eight current genera within the Laurencia complex and two new sequences of L.cervicornis and strongly support the new combination of Palisada cervicornis comb. nov. In addition, a detailed morphological characterization including the description of reproductive structures is provided. Palisadacervicornis was seen recruiting in all seasons but was typically in low abundance. Specimens grown on tiles in fish exclosure cages were devoured in less than 4h when offered to fishes. Even though many species of the Laurencia complex have chemicals that deter herbivory, species within the genus Palisada lack feeding deterrents and thus are highly palatable. We suggest that P.cervicornis is a palatable species that seems to survive in the community by obtaining a size-refuge from herbivory within turf communities.

Molecular systematics reveals increased diversity within the South African Laurencia complex (Rhodomelaceae, Rhodophyta).

Previous publications list ten species in the Laurencia complex from South Africa with all ascribed to the genus Laurencia sensu stricto. However, the diversity of the complex in South Africa has not yet been re-assessed following the numerous recent taxonomic changes. This study investigated the phylogenetic relationships and taxonomy of this group in South Africa using recent collections. Methods included molecular phylogenetic analyses of plastid rbcL gene sequences (a total of 146; including eleven outgroup taxa) using Maximum Likelihood and Bayesian Inference, and the examination of morphological and anatomical characters, including the number of corps en cerise when present. The seven genera of the Laurencia complex formed monophyletic clades with high posterior probabilities. Seventeen morphotypes were identified: 14 in the genus Laurencia sensu stricto, among which eight corresponded to Laurencia species currently recognized from South Africa and one each to species of Palisada, Chondrophycus, and Laurenciella. The six remaining morphotypes in Laurencia sensu stricto did not match any descriptions and are described here as five new species: Laurencia alfredensis sp. nov., Laurencia dichotoma sp. nov., Laurencia digitata sp. nov., Laurencia multiclavata sp. nov. and Laurencia sodwaniensis sp. nov. and a new variety: Laurencia pumila var. dehoopiensis var. nov. Laurencia stegengae nom. nov. is established to replace Laurencia peninsularis Stegenga, Bolton and Anderson nom. illeg. The diversity is likely greater, with six additional unidentified specimens found in this molecular investigation. These findings place South Africa alongside Australia in having one of the most diverse floras of this group in the world.

Molecular phylogenies support taxonomic revision of three species of Laurencia (Rhodomelaceae, Rhodophyta), with the description of a new genus

The systematics of the Laurencia complex was investigated using a taxon-rich data set including the chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene only and a character-rich data set combining mitochondrial cytochrome oxidase 1 (COI-5P), the rbcL marker, and the nuclear large subunit of the ribosomal operon (LSU). Bayesian and ML analyses of these data sets showed that three species hitherto placed in the genus Laurencia J.V.Lamour. were not closely related to Laurencia s. str. Laurencia caspica Zinova & Zaberzhinskaya was the sister group of the remaining Osmundea Stackh. species, L. crustiformans McDermid joined Palisada and L. flexilis Setch. consisted of an independent lineage. In light of these results a new genus, Ohelopapa F.Rousseau, Martin-Lescanne, Payri & L.Le Gall gen. nov., is proposed to accommodate L. flexilis. This new genus is morphologically characterized by four pericentral cells in each vegetative axial segment; however, it lacks ‘corps en cerise’ in cortical cells and secondary pit connections between cortical cells, which are characteristic of Laurencia. Three novel combinations are proposed to render the classification closer to a natural system: Ohelopapa flexilis (Setch.) F.Rousseau, Martin-Lescanne, Payri & L.Le Gall comb. nov., Osmundea caspica (Zinova & Zaberzhinskaya) Maggs & L.M.McIvor comb. nov. and Palisada crustiformans (McDermid) A.R.Sherwood, A.Kurihara & K.W.Nam comb. nov.

Chondrophycus anabeliae (Rhodomelaceae, Ceramiales), a new species in the Laurencia complex from the Mexican Caribbean

An ongoing phycological survey of the Laurencia complex in the Mexican Caribbean revealed an undescribed species belonging to Chondrophycus. The new species exhibits vegetative and reproductive structures typical of the genus, except for the presence of a slightly compressed thallus, a translucent outermost cortical cell layer with conspicuous cell wall projections, and tetrasporangia produced from a particular cell with the formation of one additional fertile periaxial cell. The phylogenetic position of this taxon was inferred based on chloroplast-encoded rbcL gene sequence analyses from 54 taxa and using three Rhodomelaceaen taxa as outgroups. The Mexican Caribbean species formed a monophyletic and fully supported clade within the Chondrophycus assemblage, but diverged at 5.8% from the most closely related taxon in the clade, whereas it diverged at 7.5% from the morphologically more closely related species C. dotyi from Kaneohe Bay, Oahu, Hawaiian Islands, indicating that the Mexican Caribbean species is morphologically and genetically distinct from other Chondrophycus species, and supporting its treatment as a new species.

Morphological and molecular evidence for Osmundea coelenterata comb. nov. (Ceramiales, Rhodophyta) from the tropical Atlantic Ocean

Background. As part of the monographic studies on the Laurencia complex (Rhodomelaceae, Rhodophyta) from Cuba, detailed taxonomic research was carried out on Laurencia coelenterata, a diminutive species collected in Santiago de Cuba, in the eastern Cuban archipelago. The vegetative and reproductive features of the species clearly belong to the genus Osmundea, a member of the Laurencia complex: two pericentral cells per each vegetative axial segment, tetrasporangia cut off randomly from cortical cells, and filament-type spermatangial branches. Goals. In this study the morphological characteristics previously unknown to Laurencia coelenterata are shown, and in order that their taxonomic position within the Laurencia complex is discussed. Furthermore, the global geographic distribution of the Osmundea species is analysed. Methods. Morphological and molecular analysis of the rbcL gene sequences were performed allied with the preparation and interpretation of phylogenetic hypotheses. Results. The new morphological analysis of the paratype specimen (# 4451) housed in the Puertorriqueno Marine Herbarium showed that Laurencia coelenterata was incorrectly placed in the genus Laurencia. The phylogenetic position of the present species was inferred by the analysis of the chloroplast-encoded rbcL gene sequences, and the range of the genetic variation found in this analysis also supports the transfer of Laurencia coelenterata to the genus Osmundea, as O. coelenterata (D. L. Ballantine et Aponte) M.T. Fujii, Senties et Areces. Conclusions. The morphological and molecular approach in algal taxonomy is allowing consolidate the nomenclatural status of the species, and the new combination for Laurencia coelenterata as Osmundea coelenterata is not an exception.

The Laurencia Paradox: An Endless Source of Chemodiversity.

Nature, the most prolific source of biological and chemical diversity, has provided mankind with treatments for health problems since ancient times and continues to be the most promising reservoir of bioactive chemicals for the development of modern drugs. In addition to the terrestrial organisms that still remain a promising source of new bioactive metabolites, the marine environment, covering approximately 70% of the Earth's surface and containing a largely unexplored biodiversity, offers an enormous resource for the discovery of novel compounds. According to the MarinLit database, more than 27,000 metabolites from marine macro- and microorganisms have been isolated to date providing material and key structures for the development of new products in the pharmaceutical, food, cosmeceutical, chemical, and agrochemical sectors. Algae, which thrive in the euphotic zone, were among the first marine organisms that were investigated as sources of food, nutritional supplements, soil fertilizers, and bioactive metabolites.Red algae of the genus Laurencia are accepted unanimously as one of the richest sources of new secondary metabolites. Their cosmopolitan distribution, along with the chemical variation influenced to a significant degree by environmental and genetic factors, have resulted in an endless parade of metabolites, often featuring multiple halogenation sites.The present contribution, covering the literature until August 2015, offers a comprehensive view of the chemical wealth and the taxonomic problems currently impeding chemical and biological investigations of the genus Laurencia. Since mollusks feeding on Laurencia are, in many cases, bioaccumulating, and utilize algal metabolites as chemical weaponry against natural enemies, metabolites of postulated dietary origin of sea hares that feed on Laurencia species are also included in the present review. Altogether, 1047 secondary metabolites, often featuring new carbocyclic skeletons, have been included.The chapter addresses: (1) the "Laurencia complex", the botanical description and the growth and population dynamics of the genus, as well as its chemical diversity and ecological relations; (2) the secondary metabolites, which are organized according to their chemical structures and are classified into sesquiterpenes, diterpenes, triterpenes, acetogenins, indoles, aromatic compounds, steroids, and miscellaneous compounds, as well as their sources of isolation which are depicted in tabulated form, and (3) the biological activity organized according to the biological target and the ecological functions of Laurencia metabolites.

C15 acetogenins from the Laurencia complex: 50 years of research – an overview

Acetogenins are secondary metabolites derived from the polyketide pathway and their potential role as chemotaxonomical markers for red algae belonging to the Laurencia complex has been long pointed out. C15 acetogenins from algae are quite different from plant acetogenins: they are usually halogenated, and have an enyne or a bromoallene terminal group. Since they were first reported, laurencin and other algal acetogenins have inspired great curiosity among natural product chemists and also those working with synthesis. This paper reviews the literature about C15 acetogenins, focusing on their distribution, chemical and biological aspects, including their reported biological activities.

A new molecular phylogeny of the Laurencia complex (Rhodophyta, Rhodomelaceae) and a review of key morphological characters result in a new genus, Coronaphycus, and a description of C.novus.

Within the Laurencia complex (Rhodophyta, Rhodomelaceae), six genera have been recognized based on both molecular analyses and morphology: Laurencia, Osmundea, Chondrophycus, Palisada, Yuzurua, and Laurenciella. Recently, new material from Australia has been collected and included in the current molecular phylogeny, resulting in a new clade. This study examined the generic delineations using a combination of morphological comparisons and phylogenetic analysis of chloroplast (rbcL) nucleotide sequence. The molecular phylogeny recovered eight (rather than six) clades; Yuzurua, Laurenciella, Palisada, and Chondrophycus showed as monophyletic clades each with strong support. However, the genera Osmundea and Laurencia were polyphyletic. Consequently, the new genus Coronaphycus is proposed, resulting in the new combination Coronaphycus elatus and a description of the new species C.novus.

Chemical diversity and antileishmanial activity of crude extracts of Laurencia complex (Ceramiales, Rhodophyta) from Brazil

Chemical profiles of extracts of four species from Laurencia complex (Ceramiales, Rhodophyta) from different populations collected along Southeast Brazilian coast were assessed by High Performance Liquid Chromatography coupled with a Diode Array Detector in order to observe geographic chemical variability. Aiming to evaluate the impact of chemical diversity on potential pharmaceutical uses, the extracts were tested against the promastigote form of Leishmania amazonensis. The most active extracts were submitted to anti-amastigote and cytotoxicity assays. Principal Component Analysis of the chromatograms resulted in four major groups of chemical profiles according to the presence of leishmanicidal chamigranes (-)-elatol and obtusol. The existence of chemotypes, displaying variable pharmacological action, is proposed for the differences observed in L. dendroidea samples. Although all extracts were found active against promastigote form of L. amazonensis, their efficacy was remarkably different and not related to the variation of (-)-elatol and obtusol, which indicates the presence of additional compounds with antileishmanial activity. Moreover, the active extracts also displayed anti-amastigote activity and none of them were considered cytotoxic. The results highlight that the knowledge of chemical geographic variability can be valuable in the search of new antileishmanial compounds from marine sources.

Spread of the introduced species Laurencia caduciramulosa (Rhodomelaceae, Rhodophyta) to the northwest Atlantic: A morphological and molecular analysis

Introduction of species is a common problem in marine environments; marine macroalgae in particular have been reported to be introduced in all oceans, mainly through transport in ballast water, ship fouling and aquarium trade. The majority of the reported alien seaweeds belong to the Rhodophyta. Recently several species of the Laurencia complex have been reported, contributing to an increase of the number of red algae being successfully introduced. Since its description as a new species from Vietnam in 1997, Laurencia caduciramulosa has been spreading steadily with disjunct reports consistently finding specimens close to harbors or major ports. Biscayne Bay, Florida, home to one of the largest ports in USA, and surrounded by the Miami metropolis, is prone to receiving introduced species. This study reports the first introduction of L. caduciramulosa in Biscayne Bay, and its spread to the NW Atlantic. Morphological analysis demonstrated that the specimens collected in Crandon Park, Biscayne Bay, are similar to other specimens of the same species described for Vietnam (original description), Brazil, the Canary Islands and Cuba. Furthermore, molecular analysis using chloroplast-encoded rbcL DNA sequences corroborated the morphological identification. The phylogenetic results suggested that populations in Brazil, Canary Islands and Cuba are recent introductions, while the position of the Florida clade can be interpreted as a distinct and earlier introduction. Due to the level of expertise and knowledge of the Laurencia complex available, we suggest that in the future this group can be used as a model to conduct population genetics analysis of all described introductions in relation to native populations in order to describe patterns of expansion and provide an insight of marine invasions processes.