(Egger, 1893)
Non-spinose, microperforate, trochospiral, with rather smooth surface with irregularly distributed micropores. Small pustules also scattered over entire surface which, if well preserved, is whitish shiny. Aperture umbilical in adult specimens, often covered by a bulla.
Ref.: Parker (1962), Kahn and Williams (1981), Li (1987), Spindler et al. (1984), Brummer (1988), Ortiz et al. (1995).
Distribution: The most widely distributed planktic foraminifer, occurring from the equator to the poles. It seems to peak in abundance in areas where nutrients are brought into the mixed layer. In the tropical South Atlantic it shows maximum abundances during April through June. Its contribution to the total planktic foraminiferal fauna may be in the order of 8-18%.