There is still limited knowledge on the taxonomy and complex life-cycle pattern of Ceratolithus cristatus, in which the heterococcolith-producing phase is associated with a ceratolith-bearing phase. A study of plankton samples from the surface-waters of the Maldives revealed several C. cristatus ceratolith-bearing specimens and a number of combination coccospheres, two of which had an association of three morphologically-distinct coccolith types—horseshoe-shaped C. cristatus CER telesmus type ceratoliths, delicate, hoop-shaped heterococcoliths and circular C. cristatus HET coccolithomorpha type planoliths. Having studied a large number of ceratoliths from these samples, we were able to demonstrate that the cristatus and telesmus ceratolith morphotypes intergrade, representing a growth sequence rather than genotypic differentiation. Based on these observations and a re-examination of other evidence, we propose that two Ceratolithus species occur in the modern ocean—C. cristatus and C. nishidae n. comb. In addition, our observations indicated that, in C. cristatus, the hoop-coccoliths and planoliths intergrade, and heterococcoliths, therefore, occur in two life-cycle phases of this species.