An updated synthesis of cyanobacteria and algae information is presented for Brazil aiming to refine the data gathered to date and evaluate the progress of the biodiversity knowledge about these organisms in the country since the publication of the Catálogo de Plantas e Fungos do Brasil. The results of 2015 showed an increase of 1,250 species (35.7%) when compared to 2010, reaching a total of 4,747 species. The most diverse classes in species number were the Bacillariophyceae, Conjugatophyceae, Florideophyceae, Cyanophyceae, Dinophyceae and Euglenophyceae. Bacillariophyceae and Cyanophyceae had the highest increase in species number in the five-year interval. The Southeast and South regions were the most diverse, however, the Northeast, with the states of Piauí and Sergipe, and the Central-west region, with Mato Grosso, Goiás and Distrito Federal, also stood out in the national algal biodiversity scenario. Despite the shortage of taxonomists and limited infrastructure, the results showed a significant improvement in the knowledge regarding the diversity of cyanobacteria and algae in the country during the study period, starting to even out regional geographical differences caused by subsampling.

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 rbcL. Four of the genera have been resolved as monophyletic, but not Laurencia s.s. In this study based on an rbcL 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.

In recent years, the use of molecular data in algal systematics has increased as high-throughput sequencing (HTS) has become more accessible, generating very large datasets at a reasonable cost. In this perspectives paper, our goal is to describe how HTS technologies can advance algal systematics. Following an introduction to some common HTS technologies, we discuss how metabarcoding can accelerate algal species discovery. We show how various HTS methods can be applied to generate datasets for accurate species delimitation, and how HTS can be applied to historical type specimens to assist the nomenclature process. Finally, we discuss how HTS data such as organellar genomes and transcriptomes can be used to construct well-resolved phylogenies, leading to a stable and natural classification of algal groups. We include examples of bioinformatic workflows that may be applied to process data for each purpose, along with common programs used to achieve each step. We also discuss possible strategies and the new skill set that will be required to fully embrace HTS as a part of algal systematics, along with considerations of cost and experimental design. HTS technology has revolutionized many fields in biology, and will certainly do the same in algal systematics.