Asapholithos anfractus
Set number: 2690
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10µm
Phanulithus anfractus Jakubowski, 1986
Calculites anfractus (Jakubowski, 1986) Varol & Jakubowski, 1989
Orastrum colligatum Henderiks & Ziveri, 1997; considered to be well preserved variation of Asapholithos anfractus.
The segments display whitish-grey interference colours, whereas the wall exhibits a white interference colour.
This species of Asapholithos is characterised by four segments that converge to form a swastika-shaped structure in the centre, surrounded by a wall. In well-preserved specimens, tooth-like projections are visible within the central opening when observed under a scanning electron microscope (SEM). These projections can also be detected by light microscopy when the specimen is oriented north–south. However, under adverse preservation conditions, particularly extensive overgrowth, the tooth-like projections commonly fuse with the rim elements and central segments. As a result, specimens typically appear to consist of four segments separated by zigzag sutures.
Henderiks, J. & Ziveri, P. 1997. Orastrum colligatum, a new holococcolith species from the Upper Albian-Cenomanian of the Russian Craton (Ukraine). Journal of Nannoplankton Research. 19(2): 109-111.
Jakubowski, M., 1986. New calcareous nannofossil taxa from the Lower Cretaceous of the North Sea. INA Newsletter. 8, 38-42.
Varol, O. & Jakubowski, M. (1989). Some new nannofossil taxa. INA Newsletter. 11(1): 24-29.
Holotype
Phanulithus anfractus
Jakubowski, 1986
Late Albian - Early Cenomanian
Moray Firth Basin, North Sea.