-(The Genus Herposiphonia (Ceramiales, Rhodophyta) in the Coral Reefs Environmental Protection Area, Northeastern Brazil, with new records for Brazil and the Atlantic Ocean). This paper presents a taxonomic study of taxa of the red algae genus Herposiphonia (Ceramiales) occurring on Maracajaú Reef in the Coral Reefs Environmental Protection Area (CREPA -Área de Proteção Ambiental dos Recifes de Corais) in Rio Grande do Norte State, along the northeastern coast of Brazil. The CREPA comprises coastline and continental shelf areas of the municipalities of Touros, Rio do Fogo, and Maxaranguape and includes sand dunes, coastal lagoons, and the adjacent shoreline and offshore reefs. Detailed morphological studies were made, considering recent taxonomic criteria for species delimitation of Herposiphonia, and five species were identified: H. delicatula, H. nuda, H. parca, H. secunda, and H. tenella, thus increasing the number of species in the genus from three to six. Herposiphonia delicatula and H. parca represent new occurrences for Brazil, and H. nuda is reported for the first time for the Atlantic Ocean.

e Antarctic Continent is undergoing environmental alterations due to global climate changes and anthropic activities. e knowledge of the biodiversity and of the ecophysiology of the organisms in this region is of essential importance to delineate strategies of protection and for the management of such a fragile region of the planet. Among the organisms to be monitored, the macroalgae are an important natural resource. Admiralty Bay, including the Martel inlet, is an Antarctica Special Management Area (ASMA), which undergoes changes during the year due to the coverage of ice creating perturbed climatic conditions, negatively a ecting the macroalgae. Previous studies suggest that Admiralty Bay is an ecotone between the Sub-Antarctic Islands and the coastal zone of Continental Antarctica. is research has the purpose of contributing to the knowledge of the macroalgae clarifying the transitory character of the macroalgal community and its distribution in the bay. From the analysis of the samples of macroalgae collected in the