Bolli (1957):
A considerable variation is observed within the species Globigerina ciperoensis Bolli. The forms included originally in this species (Bolli, 1954) have a characteristically large umbilicus; they are now given subspecies rank (G. ciperoensis ciperoensis). All gradations occur to forms with a small umbilicus associated with the typical representatives, but those with smaller umbilicus become predominant towards the end of the Globigerina ciperoensis ciperoensis zone, where the typical G. ciperoensis ciperoensis disappear. They continue into the Globorotalia kugleri zone and lower part of the Catapsy drax dissimilis zone. This form is here described as a new subspecies, Globigerina ciperoensis angudiumbilicata. Another subspecies, Globigerina ciperoensis angulisuturalis has been erected for specimens that show deep, angular, U shaped sutures between the chambers of the last whorl. Transitional forms to G. ciperoensis ciperoensis are common. The new subspecies appears to be restricted to the Globorotalia opima opima zone and the Globigerina ciperoensis ciperoensis zone.
Van Eijden & Smit (1991):
Remarks. This zonal marker is very rare at Sites 757 and 758. Most specimens we observed are intermediate with G. angustiumbilicata Bolli, 1957a. |
Bolli,H.M. (1954):
Note on Globigerina concinna Reuss 1850 (Point-a-Pierre, Trinidad) . Contributions from the Cushman Foundation for Foraminiferal Research Vol. 5(1)
Bolli,H.M. (1957):
Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I..
In: Studies in Foraminifery, Bulletin of the U.S. National Museum Vol. 215 Eds: Loeblich, A.R.Tappan, H.Beckmann, J.P.Bolli, H.M.Gallitelli, E.M.Troelsen, J.C. p. 97-123
Spezzaferri,S. and Silva,I.S.. (1990):
Oligocene planktonic foraminiferal biostratigraphy and paleoclimatic interpretation from Hole 538A, DSDP Leg 77, Gulf of Mexico . Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 83 p. 217-263
Vincent,E. and Toumarkine,M. (1990):
Neogene planktonic foraminifers from the Western Tropical Indian Ocean, Leg 115.
In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 115 Eds: Duncan, R.A..Backman, J.Peterson, L.C. p. 795-836
Van Eijden,A.J.M. and Smit,J. (1991):
Eastern Indian Ocean Cretaceous and Paleogene quantitative biostratigraphy.
In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 121 Eds: Weissel, J.Peirce, J.Taylor, E.Alt, J. p. 77-123
|
Taxon Concept provided by
