CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina? grata Todd 1957
This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.
Original Description Test small for the genus, complanate; spire depressed; periphery indented. Chambers distinct, inflated; five or six, usually of about equal size, constituting the last whorl. Sutures distinct, straight, deeply indented. Wall calcareous, finely perforate, smooth, polished, lacking both cancellations and spines. Aperture obscure, a very narrow slit extending from the umbilicus to the periphery under the edge of the last-formed chamber. Size: Diameter 0.30-0.1.1-5 mm.; thickness 0.26-0. 35 mm. Extra details from original publication This small species was only observed in the type sample. It is unique in its low-spired form with numerous inflated chambers and in its smooth and polished wall lacking any surface ornamentation. In this feature it is distinct from most of the globigerinids, and because of this lack, its generic placement is questioned. Globigerina? grata appears to be closer to Globorotalia mayeri Cushman and Ellisor than to any described species of Globigerina. Comparison with G. mayeri shows clear distinctions in that the present species lacks any suggestion of cancellation or spinosity. Furthermore, it has more distinctly inflated chambers and a very obscure aperture without an apertural lip as is present in G. mayeri. Editors' Notes This species consists of 4-6 chambers, of equal size, with distinct, radial, and deeply incised sutures. The outline is lobate, the test wall appears smooth, and the aperture is intra-extraumbilical. Diameter of holotype: 0.30-0.45 mm. Holotype deposited at the Smithsonian Museum of Natural History, Washington, D.C. (USNM 623949).
Todd questioned the generic assignment to Globigerina due to the smooth wall. This form has not been utilized by Oligocene workers and no consensus was reached within the Working Group regarding its affinity, which to date is restricted to the type sample. There is a resemblance to Tenuitella gemma (Jenkins), however, this form has a different rate of chamber size increase. Possibly a benthic form. [Berggren & Wade 2018]
References:
Berggren, W. A. & Wade, B. S. (2018). Problematica. In, Wade, B. S., Olsson, R. K., Pearson, P. N., Huber, B. T. & Berggren, W. A. (eds) Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 46(Chap 20): 511-524. gsVO
Todd, R. (1957). Smaller foraminifera, in Geology of Saipan, Mariana Islands, Pt. 3, Paleontology. U.S. Geological Survey, Professional Paper. 280-H: 265-320. gsVO
Globigerina grata compiled by the pforams@mikrotax project teamviewed: 29-5-2023
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Todd 1957 pl78 f4.JPG
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