Globorotalia juanai

NB TAXA WHICH ORIGINATE IN THE OLIGOCENE ARE NOT INCLUDED YET
Classification: pf_neogene -> Globorotalidae -> Globorotalia -> hirsuta lineage -> Globorotalia juanai
Sister taxa: G. challengeri, G. cibaoensis, G. evoluta, G. gigantea, G. hirsuta, G. juanai, G. margaritae, G. praemargaritae, G. praescitula, G. primitiva, G. scitula, G. theyeri,

Taxonomy

Citation: Globorotalia juanai (Bermudez & Boli 1969)
Rank: species
Basionym: Globorotalia juanai
Synonyms:
Variants:
NB Globorotalia praemargaritae Catalano and Sprovieri and Globorotalia margaritae primitiva Cita were also considered a variants by Kennett & Srinivasan 1983 but are now regarded as distinct species

Catalog entries: Globorotalia andalusiana; Globorotalia juanai;
Globorotalia martinezi;

Type images:

Description


Diagnostic characters: Small, very low trochospiral, biconvex, equatorial periphery slightly lobate

Aperture: : Interiomarginal umbilical-extraumbilical low arch or slit bordered by a thin lip [Aze 2011, based on Kennett & Srinivasan 1983]


Wall type: Non-spinose; Smooth [Aze 2011]

Test morphology: Test small, very low trochospiral, biconvex, equatorial periphery slightly lobulate ; axial periphery rounded with a tendency to become subangular; chambers inflated on umbilical side, 4 to 4½ in the final whorl, increasing moderately to rapidly in size; sutures on spiral side oblique, depressed , on umbilical side radial, depressed; surface smooth, finely and densely perforate, pustulate on early chambers on umbilical side; umbilicus narrow; aperture interiomarginal, extraumbilical-umbilical, a low arch or slit bordered by a thin lip. [Kennett & Srinivasan 1983]

Biogeography and Palaeobiology


Geographic distribution: Tropical to temperate. [Kennett & Srinivasan 1983]

Isotope paleobiology: Aze et al. 2011 ecogroup 4 - Open ocean sub-thermocline. Based on comparison with other species of the genus

Phylogenetic relations: Gr. (H) juanai is distinguished from Gr. (H) scitula and Gr. (H) margaritae by its rounded periphery and umbonate early chambers. We are in agreement with Stainforth et al. (1975) that Gr. (H) juanai was a direct descendant of Gr. (H) scitula, and, in turn, developed into the Gr. margaritae-Gr. hirsuta bioseries. [Kennett & Srinivasan 1983]

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within N18 zone (5.20-5.72Ma, top in Zanclean stage). Data source: Chaisson & Pearson (1997)
First occurrence (base): near base of M13a subzone (13% up, 9.7Ma, in Tortonian stage). Data source: Wade et al. (2011), additional event; position within zone determined by linear interpolation from data in table 1 of Wade et al. (2011).

Plot of occurrence data:

Primary source for this page: Kennett & Srinivisan 1983, p.134

References:

Aze, T.; Ezard, T.H.G.; Purvis, A.; Coxall, H.K.; Stewart, D.R.M.; Wade, B.S. & Pearson, P.N.P., (2011). A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data. Biological Reviews, 86: 900-927.

Bermudez, P.J. & Bolli, H.M., (1969). Consideraciones sobre los sedimentos del mioceno medio al reciente de las costas central y oriental de Venezuela. Tercera Parte. Los foraminiferos planctonicos. Boletin de Geologia, 10(20): 137-223.

Kennett, J.P. & Srinivasan, M.S., (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania, 1-265 pp.

Perconig, E., (1968). Nuove specie di foraminiferi planctonici della Sezione di Carmona (Andalusia, Spagna). Committee Mediterranean Neogene Stratigraphy, 35(3): 219-232.

Stainforth, R.M.; Lamb, J.L.; Luterbacher, H.; Beard, J.H. & Jeffords, R.M., (1975). Cenozoic planktonic foraminiferal zonation and characteristics of index forms. The University of Kansas Paleontological Contributions, 62: 1-425.


Globorotalia juanai compiled by the pforams@mikrotax project team viewed: 23-5-2017

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