A new species of Gracilaria, G. suzannae sp. nov., is described on the basis of detailed morphological, anatomical and molecular evidence from recent collections from intertidal reefs of northeastern Brazil. Diagnostic features of the new species include: tufted and tough thalli with subdichotomous, alternate to irregular branches; some branches incurved, with discrete marginal teeth, giving thalli a dentate to lacerate appearance in the upper parts; an abrupt transition of cell size between cortical and medullary regions; spermatangial conceptacles of the textorii type; and mature cystocarps with inconspicuous inner pericarp and few tubular nutritive filaments, particularly in basal portions. Universal plastid amplicon sequences of G. suzannae formed a distinct group within the genus Gracilaria, with intraspecific divergence of 0.24%. In the rbcL analysis, G. suzannae was recovered as sister to a well-supported Glade containing G. occidentalis from the United States, with interspecific divergence of 1.3%. Unlike our specimens, the thallus habit of G. occidentalis is repeatedly forked, with smooth margins and rounded apices. Furthermore, G. suzannae was phylogenetically positioned close to a major Glade composed of Indo-Pacific flat species with lobed, spiny or denticulate margins, all of which diverged 1.1 to 4.8% from G. suzannae. Gracilaria suzannae becomes the 16th flat species of Gracilaria reported for Brazil.

The genus Gracilaria is the major source of agarose in the world today and is one of the most species-rich genera in the Rhodophyta. Flat Gracilaria species are among the most taxonomically challenging taxa due to their widespread phenotypic plasticity among all species. Gracilaria cearensis is a flat species described in 1965 from Brazil. Its original description is not conducive to accurate taxonomic identifications and the delineation of this taxon remains elusive. New samples of G. cearensis were collected across a coastal length of 500 km including its type locality. Universal Plastid Amplicon (UPA) and the rbcL gene were used to confirm the phylogenetic and taxonomic status of this poorly known species. Results showed that this is a distinct species despite morphological similarities to G. hayi, G. cuneata, G. curtissiae, G. brasiliensis and G. galetensis. G. cearensis is sister to G. hayi yet the genetic divergence between these two species was 2% for rbcL and 1.08% for UPA, enough to consider them distinct taxa. However, newly generated molecular data placed G. smithsoniensis, another morphologically similar species, as conspecific with G. cearensis with only 0.07% rbcL sequence divergence between them.

A recent floristic survey of Rhodophyta from Ceará State, Brazil (02º46'30''-07º52'15''S and 37º14'54''-41º24'45''W), revealed the occurrence of 113 species distributed into 14 orders, 28 families and 63 genera. Of these, 18 species belonging to seven orders are new records; some of them poorly described and illustrated in the literature or cited only checklists. Therefore, aiming to expand the taxonomic knowledge about these poorly known species, we present detailed descriptions, illustrations, and comments on related taxa. The occurrence of Ceratodictyon scoparium is confirmed for the South Atlantic coast. The male gametophytes of Dohrniella antillarum var. brasiliensis and tetrasporophytes of Gracilariopsis silvana are illustrated for the first time. Ceramium fujianum is a new addition to northeastern Brazil. Among the new records, Callithamnion corymbosum, Ceramium clarionense, C. fujianum and C. scoparium showed a significant expansion of their geographic distribution along the Brazilian coast. Most of the newly recorded species are filamentous, small-sized or tufted algae, highlighting the need for new collections to detect the presence of these components.

This study builds on recent treatments of the marine red algal family Gracilariaceae (Gracilariales) focusing in detail on Hydropuntia and Crassiphycus. Species in these two genera often present identification problems due to high levels of morphologial similarity among genetically distinct species, and high levels of phenotypic plasticity, leading to pseudo-cryptic speciation and homoplasies. In order to resolve long standing problems, clarify some species concepts and better understand the evolution of the group, we performed phylogenetic analyses of all plastid rbcL DNA sequences available for known Hydropuntia and Crassiphycus species, including newly sequenced specimens. Our results revealed the presence of potentially undescribed species, the existence of strong phylogeographic patterns below and above the species level and helped re-delineate morphologically similar taxa. New detailed morphological descriptions for three common yet poorly known Western Atlantic species are provided: C. secundus, C. usneoides and H. rangiferina. H. rangiferina from the Indo-Pacific is a distinct species from the true H. rangiferina and represents a putative undescribed species. We also provide a time-calibrated phylogeny for the six genera in the Gracilariales to identify past geological and climatic processes associated with their origin and diversification.

The aim of this study was to carry out a taxonomic survey of epiphytic seaweeds that occur on reefs of Boa Viagem Beach, located in the metropolitan region of Recife – Pernambuco state, Brazil. The samplings were performed in the dry season (December 2009) and rainy season (April 2010) at intertidal reefs using 625 cm2 squares. Voucher specimens are deposited at the Herbarium of the Instituto de Botânica, São Paulo, Brazil (SP). A total of 48 taxa were recorded of which 20 were Chlorophyta, 27 Rhodophyta and one Heterokontophyta. The most representative orders were Ceramiales and Cladophorales, with 17 and 10 taxa respectively. Nine species are new additions to the flora of Pernambucan coast. Gelidium pusillum (Stackh.) Le Jol. 1863 and Chondracanthus saundersii C. W. Schneid. and C. E. Lane 2005 had the highest number of epiphytic macroalgae. The majority of species was collected in the rainy season and on wave-exposed sites.

Among the ten species currently accepted in the genus Calliblepharis, the only representative in the Western Atlantic is C. occidentalis. The endemic Brazilian species C. jolyi was merged into Craspedocarpus, but its generic placement is unclear. Because some species superficially resemble flat Hypnea, our knowledge about the diversity and distribution of Calliblepharis could be incomplete. Therefore, to reassess species diversity of Calliblepharis in Brazil, we carried out an rbcL-based molecular survey of specimens collected along the Brazilian coast, including the type locality of C. jolyi (State of Espírito Santo). Molecular analysis of topotypes supported the reinstatement of Calliblepharis jolyi. This species was placed within Calliblepharis sensu lato in a fully supported clade with C. fimbriata, C. occidentalis, C. rammediorum and Calliblepharis sp. Calliblepharis jolyi is easily distinguished from its congeners by the presence of conspicuous lenticular thickenings. A new record of C. saidana, a species so far known only from the Indo-Pacific, was also revealed for the Atlantic Ocean. Samples collected in São Paulo were grouped with C. saidana from Japan (type locality) with rbcL intraspecific divergence of 0.8%. Taken together, our results provide a better understanding of flat Cystocloniaceae, focusing on Brazilian members and their affinities with other species. Our study call attention to the importance of a molecular approach in specimens from type localities, using information of the original descriptions to define their taxonomic status.