Praeorbulina glomerosa circularis Blow 1956 from: Vincent, E.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 . |
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Subspecies Praeorbulina glomerosa circularis Blow 1956 |
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Diagnosis / Definition: |
Kennett & Srinivasan (1983):
Test nearly spherical with last chamber almost globular, inflated enveloping the earlier part of the test more than 75
percent; sutures depressed, surface perforate;
apertures circular to subcircular, located in the sutures between the last penultimate and earlier chamber and not in the area of final chamber. |
Discussion / Comments: |
Kennett & Srinivasan (1983):
Pr. glomerosa circularis forms part of the evolutionary lineage leading to Orbulina universa d'Orbigny and has intermediate morphology linking its immediate ancestor, Pr.
glomerosa circularis is distinguished from Pr. glomerosa glomerosa in having circular outline and smaller and more numerous apertures, along the basal sutures. It differs from
Orbulina suturalis in lacking areal apertures.
Bolli & Saunders (1985):
P. glomerosa circularis differs from P. glomerosa glomerosa in having many circular, pore like apertures between the last chamber and earlier ones rather than the slit like apertures of the latter subspecies. It is almost completely spherical with sutures hardly incised. It differs from Orbulina suturalis in having all the apertures confined to the sutures. |
Synonym list: |
Kennett & Srinivasan (1983):
Bolli & Saunders (1985):
Vincent & Toumarkine (1990):
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References: |
Blow,W.H. (1956): Origin and evolution of the foraminiferal genus Orbulina d'Orbigny . Micropaleontology Vol. 2(1) p. 57-70
Kennett,J. and Srinivasan,M.S. (1983): Neogene Planktonic Foraminifera - A Phylogenetic Atlas.
Bolli,H.M. and Saunders,J.B. (1985): Oligocene to Holocene low latitude planktic foraminifers. In: Plankton Stratigraphy Eds: Bolli, H.M.Saunders, J.B. p. 155-262
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
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