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Linked specimens: USNM-219458
Current identification/main database link: Tenuitella gemma (Jenkins 1966)
The very small-sized test is a low trochospire of more than 10 chambers with 6 chambers in the last whorl.
The initial portion of the trochospire is masked by secondary shell substance, almost flat, and slightly depressed in respect to the two last chambers of the final whorl. The chambers of the last whorl increase rapidly in size and tend to move toward the umbilical side. In lateral view the subglobular chambers are broadly rounded peripherally. The umbilicus is minute and deep. The cameral sutures are radial on the spiral and the umbilical side, and well incised. The aperture is a low arch extending from the umbilicus toward the periphery. It is bordered by a narrow rim. The calcareous perforate wall is thin, and its surface, devoid of a polygonal meshwork, is pustulate. The pustules are low-rounded, composite structures. They are of different size, almost touch each other and seem to be interconnected by radial walls. The wall pores are minute openings in the narrow spaces between the pustules and are separated by the radiating walls. This type of outer wall formation has also been found in Globigerinita boweni Brönnimann and Resig, n. sp. A
particular feature of the holotype of Globorotalia (T.) nkbrowni is the single sutural opening which occurs on the spiral suture separating the ultimate chamber from the penultimate whorl. This secondary aperture measures about 5 microns across. It is bordered by a strong,pustulate rim of about 3 microns thickness.
Size: The maximum diameter of the holotype is about 100 microns; its axial height about 40 microns. It is from Hole 64.1, Core 7, Section 2, 33-35 centimeters, Zone N. 3. The holotype is illustrated on Plate 40,Figure 2. It coils to the left.This species is named for the late Noel King Brown, Jr.,Houston, Texas, U.S.A.
Extra details from original publication
Paratypes typically show 5 to 7, normally 6, chambers,which gradually increase in size, in the final whorl as added. Coiling is random. The maximum diameter varies around 100 microns. These specimens are, in general morphology, close to Globorotalia (Turborotalia) gemma Jenkins, 1965, which according to Blow (1969) extends from P. 16 to the lower part of Zone N. 1, whereas Globorotalia nkbrowni, n. sp., has been recorded only in Zone N.3. The surface of Globorotalia (T.) gemma, as illustrated by the scanning micrograph (Blow, 1969, pi. 34, fig. 9) of the spiral side of a specimen from Zone P. 19, Lindi area, Tanzania, is sparsely pustulate and the dorsal radial sutures are oblique. The specimen lacks a secondary opening on the dorsal side. Paratypes of Globorotalia (T.) nkbrowni invariably exhibit this secondary opening. By the outer formation and by the secondary opening Globorotalia (T.) nkbrowni differs from all
other minute turborotaliids.
Globorotalia (Turborotalia) nkbrowni compiled by the pforams@mikrotax project team viewed: 25-10-2020
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