Catalog - Rugoglobigerina reicheli pustulata

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Rugoglobigerina reicheli pustulata

Citation: Rugoglobigerina reicheli pustulata Bronnimann 1952

Type specimens: 371326 Holotype. T.L.L.Cat.Nos.155591-155594 Plate 2,figs.7-9.

Type sample (& lithostrat): Globotruncana mayaroensis zone, Guayaguayare beds

Type age (chronostrat): Maestrichtian, Upper Cretaceous

Type locality: Globotruncana mayaroensis zone, Guayaguayare beds,Maestrichtian,Upper Cretaceous-,Trinidad, B.W.I.

Type repository: Washington; USNM

The last whorl of the small to medium-sized low trochoidal test is 5-chambered. The centrally slightly depressed spiral side exhibits about 2 whorls. Due to the rugose surface, details of the initial stage could not be observed. The chambers are subglobular throughout the last whorl, the earlier ones occasionally provided with large spicules. The chambers increase in size as added. The end chamber, however, can be smaller than the penultimate one and usually is clearly displaced toward the umbilicus. Such size reduction and displacement appear to be typical features of the Rugoglobigerinas. The end chamber is distinctly truncate at the apertural side. The sutures are depressed and straight. The circular umbilicus is deep and usually filled with matrix. Remains of a covering plate were observed along the truncate edges of the chambers. The large, semicircular aperture of the end chamber opens into the umbilicus. The apertures of the preceding chambers are not known. The walls appear to be thick, and the surface is coarsely rugose, especially in the early stages. The ornamentation of the last chambers exhibits the characteristic meridional pattern. All the investigated specimens are dextrally coiling.

Maximum diameter 0.35mm. End chamber:radial diameter 0.125mm.;tangential diameter 0.175mm.; thickness 0.20mm.

The subspecies pustulata is a completely Globigerina-like form and therefore can be distinguished without difficulty from the spinose subspecies reicheli and from the asteroid species of the subgenus Plummerella. It is separated from the related Rugoglobigerinas by the number of chambers in the last whorl, by the less developed meridional ornamentation, and by the much smaller size.

References:

Brönnimann, P. (1952c). Brönnimann, P. (1952). Globigerinidae from the Upper Cretaceous (Cenomanian-Maestrichtian) of Trinidad, B. W. I. Bulletins of American Paleontology. 34(140): 1-70. Bulletins of American Paleontology. 34(140): 1-70. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Rugoglobigerina reicheli pustulata Bronnimann 1952

Rugoglobigerina reicheli pustulata

References:

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