Nannotax Enabling nannofossil research

Description: Similar to D. exilis but with large distal boss and very large, mushroom-shaped proximal boss. Central-area narrow.

Remarks: This form was independently illustrated by Filewicz (1985) as D. tuberi; Theodoridis (1984) as D. signus, and Moshkovitz & Ehrlich (1980) as D. petaliformis. The forms illustrated are of the same age (NN4-5) and extremely similar. They are clearly the same taxon, and given their distinctive form and restricted range it is useful to distinguish them. D. signus is an inappropriate name for them, since D. signus as described by Bukry (1971) lacks central knobs. Apart from the knobs they are normal D. exilis specimens and all authors noted that forms with large knobs graded into others with small knobs.The orientation of the distal knob appears aberrant, with its rays pointing in radial rather than inter-radial directions. However, it has normal sutural ridges and the peculiar orientation of knob may be associated with its flaring form.

Range: NN4 to 5.

Synonyms:

Discoaster signus Bukry, 1971 sensu Theodoridis, 1984;

Discoaster tuberi Filewicz, 1985.