Research identifies new taxa of red marine algae

While investigating plants of the Laurencia complex in the Atlantic Ocean, researchers confirmed one new genus and two new species.

By Fabio Reynol

Agência FAPESP – Two new species of marine algae Laurenciella marilzae and Osmundea sactarum and the genus Laurenciella were recently confirmed by researchers on the project “Diversity and phylogenetic relationships of marine benthic algae: the Laurencia complex (Rhodophyta) in the Atlantic coasts of Tropical and Subtropical regions,” funded by FAPESP through a regular line of research project award.

The two species were discovered more than 10 years ago in the Laje de Santos Marine State Park (SP) during work on the study “Algaflora of the State of São Paulo,” a thematic project under the BIOTA-FAPESP Program. At the time, however, it was not possible to conduct a taxonomic identification at the species level until DNA sequences could be generated for genetic comparisons.

The identification began later, after new collections were obtained at the Laje de Santos during the doctoral work of Renato Rocha-Jorge, who received funding from FAPESP. Rocha-Jorge studied the macroalgal flora of ocean islands along the coast of São Paulo, and was advised by Mutue Toyota Fujii of the Institute of Botany of the São Paulo Secretariat of Environment.

“We attempted to obtain more information about the taxonomic entities of the Laurencia complex by better describing the genus and species through molecular analyses,” said professor Valéria Cassano from the Botany Department of the Biosciences Institute of the University of São Paulo (IB-USP), lead investigator on the regular line of research project.

The study involved research institution professionals from six countries along the shores of the Atlantic Ocean: Spain, the United States, Mexico, Portugal and Venezuela in addition to Brazil. Thus, it was possible to obtain a biogeographical survey with morphological and molecular analyses of the algae of the Laurencia complex from different regions of the ocean.

The project included collaboration from researchers at the Botanical Institute of the Metropolitan Autonomous University in Iztapalapa, Mexico, Florida International University in the United States, the Central University of Venezuela, the University of the Azores in Portugal, and the University of La Laguna in the Canary Islands of Spain. The study resulted in the publication of ten scientific articles and one chapter in a book that revised three genera of the Laurencia complex for the Canary Islands.

The Laurencia complex is a grouping that brings together six genera of red algae, a number that could increase or be sub-divided after studies such as these.

Medicinal substances

The investigation of these algae, according to Cassano, is particularly interesting to the chemical and pharmaceutical industries because plants are producers of secondary metabolites, which are molecules with potential medicinal properties.

According to the literature, a wide variety of substances produced by the algae of the Laurencia complex, such as those with antifungal and anti-carcinogenic properties and even those that fight the protozoa that causes leishmaniasis, have already been identified.

The identification of marine algae used to be conducted according to their morphological characteristics, complicating the precise determination of genera and species. However, by using molecular analysis on the Laurencia complex beginning in 2000, specific genetic markers began to be utilized to differentiate species and group them by genus in a more cohesive manner that considered their evolutionary lineage.

In this project, the researchers used the DNA barcoding technique and comparisons of the DNA sequences of other molecular markers for phylogenetic purposes, in addition to the traditional morphological study of the species.

The work consisted of an evolution of partnerships that began in 2005 between universities in Mexico, Brazil, Portugal and Spain, presenting important advances to the organization and phylogeny of the Laurencia complex in addition to optimizing the collections of algae present in the eastern and western Atlantic Ocean and on rocky cliffs and limestone reefs at depths of up to 20 meters.

“International collaboration expands the representative quality of the collections and has gained momentum in this recent study with the participation of Venezuela and the United States,” Cassano added.

In Brazil, the algae catalogued in the complex are found along the coast from the Brazilian states of Ceará to Rio Grande do Sul, an area in which five of the six genera represented by the Laurencia complex have already been found.

The researchers have identified 12 potential new species, three of them found in Brazilian waters. “They are specimens that are not grouped with any other species, but more morphological and molecular information is needed to confirm this,” the researcher said.

Classifying aquatic plants is not an easy task. The wide range of variation in morphology, the absence of descriptions that are complete and uniform and the difficulty in observing some of the characteristics required for a precise identification of the taxa all contribute to increasing the confusion regarding their taxonomy, which further complicates identification and nomenclature. As a result of these challenges, the group’s taxonomy is undergoing constant modification as the research goes forward and new elements of differentiation are used.

“We have a long road of studies ahead and many new species to be described; thanks to molecular biology, we have the tools for this,” Cassano said.