Nannotax Enabling nannofossil research

Description: Species of Calcidiscus producing circular to sub-circular coccoliths with, closed central-area.

Remarks: This is something of a default name appied to a wide range of morphotypes but in most Neogene assemblages there is clearly a separation between slightly sub-cicular forms with a closed central area (leptoporus) and circular froms with an open central area (tropicus). In the modern nannoflora C. leptoporus has often been subdivided into small (<5µm), intermedate (5-8µm), and large (>8µm) forms. The large forms are now distinguished as C. quadriperforatus.

Original description:

Variants:

C. fuscus (Backman, 1980) Janin, 1987 - small , broadly elliptical;

C. pataecus (Gartner, 1967) de Kaenel and Villa, 1996 - small , broadly elliptical.