Nannotax Enabling nannofossil research

Description: 6-rayed discoaster with strong bifurcations; rays flat and proximal and distal surfaces only weakly differentiated; central-area narrow and with only weak bosses. Bifurcations well developed.

Remarks: Rather a generalised form, but distinguishing it gives stratigraphic value to D. exilis and D. variabilis. NB The name D. challengeri has priority over all other commonly applied names for bifurcate 6-rayed discoasters.

Range: NN5 to 10.

Variants:

D. perclarus Hay in Hay et al., 1967 - longer bifurcations and more delicate form;

D. pseudovariabilis Martini and Worsley, 1971 - with bifid proximal extensions between the bifurcations and so weakly trifurcate.