The analysis of water samples collected during the MD218 CROTALE expedition (February–March, 2019), and the 4th Indian Southern Ocean Expedition (SOE) (January–February, 2010) (re-visited samples) resulted in the occurrence of a new coccolithophore species belonging to the genus Alisphaera, and is named Alisphaera crostae sp. nov. This new species appears monomorphic and shows distinctive morphological diff erences in terms of its coccolith size, fl ange structure, and nodules, compared to other known Alisphaera species. In this study, morphological diff erences between A. crostae and other Alisphaera species are illustrated and compared. We suggest that the genus Alisphaera may have a higher diversity and may possess a wider distribution than previously evidenced, which requires more careful observation.