Nannotax

Coccosphere: Dimorphic with inner spine-bearing and outer non spine-bearing coccoliths, distributed around coccosphere. Usually non-motile and no differentiation of circum-flagella coccoliths but occasional cells with flagella have been observed (Lohmann 1902, Probert pers. comm.).

Coccoliths: Radial cycle absent, lamellar cycle fills central area and forms spine.

Type species: R. clavigera.

Synonym: Rhabdolithus Kamptner ex Deflandre in Grassé 1952.

Variant: Palusphaera -similar to Rhabdosphaera but monomorphic, all coccoiths have spines. in the fossil record these would be included in Rhabdosphaera