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Gansserina repanda


Classification: pf_mesozoic -> Globotruncanidae -> Gansserina -> Gansserina repanda
Sister taxa: G. gansseri, G. repanda, G. wiedenmayeri, G. sp.,

Taxonomy

Citation: Gansserina repanda (Bolli, 1957)
Rank: Species
Basionym: Globotruncana repanda

Type images:

Original description: Globotruncana repanda Bolli 1957: "Shape of test a very low trochospiral, spiral side concave, umbilical side strongly inflated; equatorial periphery lobate, early chambers of last whorl with double keel, which may be absent in the ultimate and penultimate chambers. Wall calcareous, perforate; surface in well-preserved specimens slightly rugose, especially on the umbilical side. Chambers globular to hemispherical, twelve to fifteen, arranged in two to three whorls; the four chambers of the last whorl increase rapidly in size, earlier whorls small by comparison. Sutures on spiral side almost radial, depressed; on umbilical side radial, depressed. Umbilicus deep, wide. Primary apertures interiomarginal, umbilical; tegillia with accessory apertures not preserved in Trinidad material, but present in specimens of this species from the Gulf Coast. The twenty-five specimens counted all coiled dextrally. "Dimensions of holotype. - Diameter 0.4 mm.; thickness 0.24 mm. "Remarks. - In its planoconvex shape, Globotruncana repanda shows similarities to Globotruncana helvetica Bolli, Globotruncana gansseri Bolli, Globotruncana concavata (Brotzen) [Rotalia concavata, 1934], and Globotruncana ventricosa White [Globotruncana canaliculata (Reuss) var. ventricosa, 1928]. It differs from the last two in having in the last whorl fewer and more inflated chambers, which are bent upwards on the spiral side. It is usually slightly smaller in size. From Globotruncana helvetica and Globotruncana gansseri the new species differs in having two peripheral keels, a more concave spiral side, and a less rugose surface. The stratigraphic range of Globotruncana repanda is similar to that of Globotruncana ventricosa, but differs considerably from that of the other three species."

Entries in the Catalog of original descriptions: Globotruncana repanda;

Geological Range:
Last occurrence (top): within G. ventricosa zone (76.18-79.20Ma, top in Campanian stage). Data source: [copied from Chronos database]
First occurrence (base): within G. elevata zone (79.20-84.19Ma, base in Santonian stage). Data source: [copied from Chronos database]

Plot of occurrence data:

NB Plotting of Neptune data has been disabled on the Mesozoic pages because the dataset is both small and badly affected by a few sites with erroneous age models (our obs Huber, Petrizzo, Young, Nov 2016). The data can still be viewed via the range plottertool - tools menu.

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Planoconvexaperture:Umbilical
umb chamber shape:Globularcoiling axis:Very lowperiphery:Double keelaperture border:N/A
sp chbr shape:Petaloidumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:N/A
umbilical or test sutures:Moderately depressedumb depth:Deepwall texture:Mod. Pustuloseshell porosity:Finely Perforate: 1-2.5┬Ám
spiral sutures:Moderately depresseddiameter mm:0.33width mm:breadth mm:0.17
final-whorl chambers:4.0-4.5

References:

Bolli, H.M., (1957). The foraminiferal genus Schackoina Thalmann, emended, and Leupoldina, n. gen. in the Cretaceous of Trinidad, B. W. I. Eclogae Geologicae Helvetiae, 50(2): 271-278.

Bolli, H.M., (1957). The genera Praeglobotruncana, Rotalipora, Globotruncana, and Abathomphalus in the Upper Cretaceous of Trinidad, B. W. I. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 51-60.


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Gansserina repanda compiled by the pforams@mikrotax project team viewed: 26-9-2017

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