Navilithus altivelum: a remarkable new genus and species of deep photic coccolithophores

Abstract. A very distinctive new deep-photic coccolithophore is described from the NE Indian Ocean. The new species is trimorphic with: 200–300 body coccoliths bearing low spines attached by narrow stems to a basal narrow-rimmed placolith structure; up to 18 circum-flagellar coccoliths with tall sail-like spines; and up to 22 coccoliths with moderately elevated spines occurring both around the circum-flagellar coccoliths and antapically. These features make the coccolithophore unique and require placement in a new species and genus. The basal structure, however, shows similarities to a recently recognized group of narrow-rimmed placoliths. Hence, the new coccolithophore provides some support for this grouping as a significant addition to our understanding of coccolithophore biodiversity, and potentially an explanation for a set of anomalous molecular genetic results. In addition the new taxon provides further evidence that the deep-photic coccolithophore community is more diverse than has been assumed.