Caloglossa species diversity (Delesseriaceae, Rhodophyta) based on morphology and DNA data with emphasis on southeastern Brazil

Species of the marine red algal genus Caloglossa are among taxonomically confuse taxa as a consequence of their widespread phenotypic plasticity. Therefore, in this study, we assessed the specific diversity of Caloglossa from southeastern Brazil by combining both morphological observations and molecular markers. We used cytochrome oxidase subunit I (COI-5P) and partial sequences of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene to investigate 15 taxa of Caloglossa. The four species previously referred to Brazil, C. apomeiotica, C. confusa, C. leprieurii, and C. ogasawaraensis, were also confirmed in this study, and C. rotundata is reported for the first time in the Atlantic Ocean; tetrasporangia are described for the first time for the latter species. Caloglossa confusa has its geographical distribution extended to northeastern Brazil, and C. apomeiotica represents the first record for Sao Paulo State. Furthermore, the rbcL sequence data indicate that the molecular distinction within the same species ranges from 0 to 5.4%, whereas interspecific divergence ranged between 2.4 and 14.5%, and COI-5P interspecific divergence ranged from 2.5 to 3.3%. The low intraspecific divergence observed (0-0.01%) for COI-5P results from the few samples sequenced.