ABSTRACT: Ten new species of the coccolithophore genus Syracosphaera are described from temperate and sub-tropical to tropical waters: Syracosphaera andruleitii sp. nov., Syracosphaera castellata sp. nov., Syracosphaera didyma sp. nov., Syracosphaera hastata sp. nov., Syracosphaera hirsuta sp. nov., Syracosphaera leptolepis sp. nov., Syracosphaera operculata sp. nov., Syracosphaera reniformis sp. nov., Syracosphaera serrata sp. nov. and Syracosphaera squamosa sp. nov. An emended description is given for Syracosphaera nanaKamptner. These and other Syracosphaera species are placed in a revised classification scheme for the genus, based on the morphological structure of endothecal and exothecal coccoliths, and coccosphere characteristics. The Syracosphaera noroitica group is introduced for species with exothecal murolithswith a beaded proximal flange and varimorphic endothecal muroliths. The three new subgroups in the Syracosphaera nodosa group are characterised by their exothecal coccolith structure: subcircular and delicate in the leptolepis-subgroup, oval in the nana-subgroup and laminated in the squamosa-subgroup. The corolla-subgroup, with its large funnel- shaped exothecal coccoliths, is new in the Syracosphaera pulchra group.