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Since 2011, massive new strandings of holopelagic <i>Sargassum</i> have been reported on the coasts of the Caribbean, northern Brazil, Guiana, and West Africa, causing severe economic and ecological damage. Three common morphotypes (<i>S. fluitans</i> III, <i>S. natans</i> I, and <i>S. natans</i> VIII) were identified as responsible for these catastrophic events, with dominance shifts between them over time. However, the taxonomic status of these holopelagic <i>Sargassum</i> morphotypes remains unclear. Using an integrative taxonomy framework, combining a morphological study and molecular analyses, this study aimed to clarify their taxonomic status. Morphological analyses of 54 characters revealed no intermediate form between the three morphotypes, with the overall shape, nature of the axis, and size and shape of blades and vesicles being the most discriminating. An analysis of mitochondrial (<i>IGS</i>, <i>cox2</i>, <i>cox3</i>, <i>mt16S rRNA</i>, and <i>nad6</i>) and plastid (<i>rbcL</i>) markers confirmed the genetic divergence among the three morphotypes, with a lower level of divergence between the two <i>S. natans</i> morphotypes. Without additional molecular characterization, these morphotypes cannot be classified as three distinct species. However, due to their distinct morphological characteristics and sympatry within drifting aggregations, a revision of holopelagic species names is proposed, with <i>Sargassum fluitans</i> var. <i>fluitans</i> (for <i>S. fluitans</i> III), <i>Sargassum natans</i> var. <i>natans</i> (for <i>S. natans</i> I), and <i>S. natans</i> var. <i>wingei</i> (for <i>S. natans</i> VIII<i>)</i>. This revision provides necessary clarity on the species involved in inundations of the tropical Atlantic.