Taxonomy
Original description: Shape of test very low trochospiral, biconvex; equatorial periphery lobate; a faint keel is often observed in last chambers; it may be ornamented with minute spines on peripheral edge. Wall calcareous, perforate, surface smooth. Chambers strongly compressed, 10-12, arranged in 2 whorls; the 5-6 chambers of the last whorl increase rapidly in size; the early whorl minute by comparison. Sutures on spiral side radial or slightly curved, depressed; on umbilical side radial, depressed. At umbilicus each chamber of last whorl extends towards the center, leaving only a small portion open. Aperture a low arched, interiomarginal, extraumbilical-umbilical slit. Coiling predominantly dextral; of 37 specimens counted only 4 coiled sinistrally.
Entries in the Catalog of original descriptions: Praeglobotruncana coarctata
Character matrix
| test outline: | Lobate | chamber arrangement: | Trochospiral | edge view: | Equally biconvex | aperture: | Extraumbilical-peripheral |
| sp chamber shape: | Inflated | coiling axis: | Very low | periphery: | Single keel | aperture border: | Thin lip |
| umb chbr shape: | Inflated | umbilicus: | Wide | periph margin shape: | Moderately rounded | accessory apertures: | Relict |
| spiral sutures: | Strongly depressed | umb depth: | Shallow | wall texture: | Smooth | shell porosity: | |
| umbilical or test sutures: | Strongly depressed | final-whorl chambers: | 5-6 | N.B. These characters are used for advanced search. N/A - not applicable | |||
Geological Range:
Last occurrence (top): within R. calcarata zone (75.06-75.91Ma, top in Campanian stage). Data source: [copied from Chronos database]
First occurrence (base): within G. ventricosa zone (76.18-79.20Ma, base in Campanian stage). Data source: [copied from Chronos database]
Plot of range and occurrence data:
Bolli, H. M. (1957e). The genera Praeglobotruncana, Rotalipora, Globotruncana, and Abathomphalus in the Upper Cretaceous of Trinidad, B. W. I. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 51-60. gs Pessagno, E. A. (1967). Upper Cretaceous planktonic foraminifera from the western Gulf Coastal Plain. Palaeontographica Americana. 5: 245-445. gs OReferences:

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Loeblichella coarctata compiled by the pforams@mikrotax project team viewed: 7-10-2026
Short stable page link: https://mikrotax.org/pforams/index.php?id=110321 Go to Archive.is to create a permanent copy of this page - citation notes |
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