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"Globorotalia" nana Bolli 1957 from: Kennett, J.Srinivasan, M.S. (1983): Neogene Planktonic Foraminifera - A Phylogenetic Atlas.
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Species "Globorotalia" nana Bolli 1957


Diagnosis / Definition:
Kennett & Srinivasan (1983):
Test small, very low trochospiral, tightly coiled, equatorial periphery quadrilobate, axial periphery rounded; chambers four to four and a half in the final whorl, increasing rapidly in size as added; sutures on both spiral and umbilical sides radial and depressed; surface distinctly cancellate with subhexagonal pits; umbilicus narrow; aperture interiomarginal, extraumbilical-umbilical, a low arch bordered by a thick rim.
Discussion / Comments:
Kennett & Srinivasan (1983):
"Gr." nana is distinguished from Gr. (Globoconella) incognita by having a low aperture and from Gr. (Jenkinsella) opima by being smaller and more tightly coiled, with four to four and a half chambers in the final whorl. "Gr." nana seems to be a central, ancestral globorotalid stock from which several Neogene lineages radiated close to the Oligocene-Miocene boundary. In temperate areas, "Gr." nana seems to have evolved in the early Miocene to Gr. (Globoconella) incognita, the earliest member of the Globoconella lineage, by developing a high-arched aperture.
Synonym list:
Kennett & Srinivasan (1983):
1957 Globorotalia opima nana Bolli. - Bolli : p.118 pl 28 figs 3 a-c
Was used in synonym list of:
References:

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

Kennett,J. and Srinivasan,M.S. (1983):
Neogene Planktonic Foraminifera - A Phylogenetic Atlas.

Anonymous: Unedited TaxonConcept data
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