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Costellagerina bulbosa


Classification: pf_mesozoic -> Hedbergellidae -> Costellagerina -> Costellagerina bulbosa
Sister taxa: C. bulbosa, C. pilula, C. sp.,

Taxonomy

Citation: Costellagerina bulbosa (Belford, 1960)
Rank: Species
Basionym: Rugoglobigerina bulbosa

Type images:

Original description: Rugoglobigerina bulbosa Belford 1960: Diagnosis: Test trochoid, spiral surface flat or only slightly convex, chambers globular, inflated, usually 4 in last whorl. Sutures depressed, surface of test ornamented with small ridges, on some chambers in a meridional pattern. Aperture interio- marginal umbilical, large.

Description: Test trochoid, both dextrally and sinistrally coiled forms known, with the latter the more common; umbilicus small, circular, usually infilled. Chambers globular, inflated, forming to 2-2½ whorls, successive whorls strongly overlapping and spiral surface flat or only slightly convex; usually four but sometimes five chambers on last whorl increasing only slowly in size as added. Very rare specimens have last chamber smaller than penultimate chamber, formed to one side of test and always smooth. Earlier chambers and sutures on spiral side often obscured by surface ornamentation, the later sutures straight or slightly curved, depressed; sutures on umbilical side straight, depressed. Surface of test ornamented with small discontinuous ridges, irregularly arranged on earlier chambers and forming meridional pattern on chambers of last whorl. Vail of test calcareous, finely perforate, radiate in structure. Aperture interiomarginal umbilical, large and arcuate, not always observed; well-preserved specimens have distinct tegilla extending over umbilicus.

Entries in the Catalog of original descriptions: Rugoglobigerina bulbosa;

Geological Range:
Last occurrence (top): within G. elevata zone (79.20-84.19Ma, top in Campanian stage). Data source: [copied from Chronos database]
First occurrence (base): within D. asymetrica zone (84.19-86.71Ma, base in Coniacian stage). Data source: [copied from Chronos database]

Plot of occurrence data:

Dec 2017 - Plotting of Neptune data has been re-enabled on the Mesozoic pages following revision of the age-models in Neptune. The data is, however, still very sparse for the Early Cretaceous

Character matrix

test outline:Subcircularchamber arrangement:Trochospiraledge view:aperture:Umb.-extraumbilical
umb chamber shape:Inflatedcoiling axis:Low-moderateperiphery:N/Aaperture border:Tegilla
sp chbr shape:Inflatedumbilicus:Wideperiph margin shape:Broadly roundedaccessory apertures:None
umbilical or test sutures:Strongly depressedumb depth:Deepwall texture:Meridional costellaeshell porosity:
spiral sutures:Strongly depresseddiameter mm:0.34 to 0.39width mm:breadth mm:0.19 to 0.26
final-whorl chambers:4.0-5.0

References:

Belford, D.J., (1960). Upper Cretaceous foraminifera from the Toolonga Calcilutite and Gingin Chalk, Western Australia. Australia Bureau of Mineral Resources, Geology and Geophysics Bulletin, 57: 1-198.


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Costellagerina bulbosa compiled by the pforams@mikrotax project team viewed: 23-1-2018

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