Globigerinoides triloba Reuss 1850 from: Chaisson, W.P.Leckie, R.M. (1993): High-Resolution Planktonic Foraminifer Biostratigraphy of Site 806, Ontong Java Plateau (Western Equatorial Pacific). In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 130 Eds: Berger, W.H.Kroenke, L.W..Mayer, L.A..et al. p. 137-178 . |
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Species Globigerinoides triloba Reuss 1850 |
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Diagnosis / Definition: |
Kennett & Srinivasan (1983):
Test trochospiral, chambers spherical, three in the final whorl increasing rapidly in size as added; sutures on both sides gently curved and depressed; surface distinctly cancellate (PI. 10, Fig. 4), the pores located in well-developed pore pits separated by interpore ridges; primary aperture interiomarginal, umbilical, a low slit, supplementary aperture along spiral sutures in the form of irregular slit. |
Discussion / Comments: |
Kennett & Srinivasan (1983):
This species is distinguished from all other Globigerinoides by its relatively low-arched, slitlike primary and supplementary apertures. Gs. triloba differs from Gs.
immaturus in having the final chamber larger than all the earlier chambers combined and in its low aperture.
Bolli (1957):
Globigerinoides sacculifera (Brady) and G. sacculifera immatura Le Roy are closely related to G. triloba (Reuss). Forms transitional between those species are often difficult to place with certainty. The members of the group appear almost simultaneously in the Cipero formation towards the top of the Globorotalia kugleri zone. For these reasons Globigerinoides sacculifera and G. sacculifera immatura are here treated as subspecies of G. triloba which has priority as a specific name. A fourth subspecies, G. triloba attiapertura, is here described as new. Spiral and umbilical views of the subspecies of G. triloba, G. rubra (d'Orbigny) and G. obliqua, new species, are shown in text figure 21. G. triloba triloba differs from G. triloba immatura in having a final chamber that is larger than all the earlier chambers combined. G. triloba sacculifera differs from G. triloba immatura in having a terminal, elongate, sacklike chamber. G. triloba altiapertura differs from G. triloba immatura in having a high arched, primary aperture. Globigerinoides rubra (d'Orbigny) differs from the G. triloba group and G. obliqua, new species, in the position of the primary interiomarginal, umbilical aperture and supplementary sutural apertures. In 0. rubra each aperture is a fairly high arch symmetrically placed above the suture between two earlier chambers (see text fig. 21, Nos. 6a,b); in the subspecies of G. triloba and G. obliqua each aperture is placed above the two sutures between three earlier chambers (see text fig. 21, Nos. 4a,b, 5a,b) or distinctly asymmetrical above the suture between two earlier chambers (see text fig. 21, No. 1a).
Chaisson & Leckie (1993):
Similar species: Typical specimens are coarsely cancellate, and the test is
more compact than early forms of Globigerinoides sacculifer. Also see Globigerinoides
sicana/bisphericus. |
Synonym list: |
Kennett & Srinivasan (1983):
Chaisson & Leckie (1993):
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Was used in synonym list of: |
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References: |
Reuss,A.E. (1850): Neue Foraminiferen aus den Schichten des Österreichischen Tertiärbeckens . K. Akad. Wiss Wien, Math.-naturw. Kl. Vol. 1 p. 365-390
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.
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
Chaisson,W.P. and Leckie,R.M. (1993): High-Resolution Planktonic Foraminifer Biostratigraphy of Site 806, Ontong Java Plateau (Western Equatorial Pacific). In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 130 Eds: Berger, W.H.Kroenke, L.W..Mayer, L.A..et al. p. 137-178
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