Extension of the distribution range of Hypnea stellulifera (Cystocloniaceae, Rhodophyta) to the South Atlantic: Morphological and molecular evidence ☆

Abstract Hypnea stellulifera was, until now, considered endemic to tropical Asia. Here, we report for the first time the expansion of its distribution to the Atlantic Ocean on the basis of collections from the northeast of Brazil. Comparison of morphological features of our specimens with Asian specimens of H. stellulifera and molecular data analysis allow us to confirm its identification. Samples analyzed in this study represent the first assessment of Hypnea sequences collected in a tropical area from South America. Among the three genes analyzed (the mitochondrial cox 1 and the plastidial UPA and rbcL ), UPA was the most conserved, and the cox 1 was the most variable marker. Despite this, all three markers were efficient as DNA barcoding markers for Hypnea . In our phylogenetic analysis, H. stellulifera had a sister relationship with the clade that includes H. cornuta , H. musciformis , H. flagelliformis , and H. chordacea . Our results demonstrate that the analysis of Hypnea species collected at large geographic distances and/or in different tropical areas reveals a higher degree of intraspecific variation as well as decreased interspecific divergence among distinct species from closer areas. These findings corroborate the necessity of a combined analysis of morphology and different genetic markers for a better understanding of taxonomy and phylogeny of the genus Hypnea .