Nannotax

Coccosphere: Spherical, usually non-motile but occasionally with flagella (Lohmann 1902, Probert unpubl.). Dimorphic with spine-bearing and spine-less coccoliths.

Coccoliths: Spines robust, formed of five clockwise-spiral sets of elements with pentameral terminal papilla. Base of coccoiths elliptical/oblong, 3-3.5 µm. Spine-bearing liths with wider rim than non spine-bearing liths.

In LM core of spine appears to be hollow, coccolith base is often missing but spine form is very characteristic.

Fossil specimens:

	LM of typical R. clavigera
	SEM of R. styiifera morphotype
	distal view of non spine-bearing coccolith
	proximal view of non spine-bearing coccolith

Range:

Early Miocene (caNN4) to recent (NN21).

Variants:

Rhabdosphaera clavigera var. stylifera (Lohmann, 1902) Kleijne and Jordan, 1990 - form with narrow,
parallel-sided, spine. NB Aubry & Kahn (2006) have provided strong evidence that clavigera and stylifera are discrete species, with clavigera being larger as well as more robust. However in the fossil record only the clavigera type is commonly preserved.

Rhabdosphaera procera Martini, 1969 - delicate form, similar to Rh. c. stylifera; Rhabdosphaera sicca (Stradner, 1963).