Catalog - Turborotalita primitiva

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Turborotalita primitiva

Citation: Turborotalita primitiva Brönnimann & Resig 1971

Type age (chronostrat): Oligocene

Type locality: SW Pacific, Ontong Java Plateau, Hole 64.1 Core 7, Sec.2, 33-35cm, Zone N.3

Type repository: Washington; USNM

The very small-sized test is a very low tightly coiled trochospire of about twelve chambers with five chambers in the final whorl. The spiral and the umbilical sides are slightly convex. The trochospire is flat over its initial portion. The outline, as seen in spiral and in umbilical view is broad-elliptic. Ultimate and penultimate chambers are weakly lobate. This is reminiscent of the much stronger radial extension of the final chamber(s) in Turborotalita humilis (Brady), 1884, (Banner and Blow, 1960, pi. 8, fig. 1; Parker, 1967,pi. 17, fig. 10). The chambers of the last whorl increase gradually in size. They are distinctly compressed in axial direction. The cameral spiral sutures on the dorsal and the cameral sutures on the umbilical side are not incised. The cameral sutures are radial on both sides of the test. The sutures of the early coil are barely discernible. The umbilicus is partially covered by an extension of the ultimate chamber which opens with an elongate slit-like umbilical aperture with a pustulate margin. There seems to be no apertural rim or umbilical bulla. In the umbilical depression the aper-ture of the penultimate chamber is also visible. The thick calcareous wall is perforate and the surface pustulate. The umbilical side of the ultimate chamber exhibits very few and widely spaced wall pores. The surface between the pores is finely granular. A very few large irregularly shaped pustules of up to 6 microns in diameter occur on this finely pustulate surface. The surface of the two last-formed chambers are more strongly pustulate than are those of the earlier chambers (scanning micrograph Plate 26, Figure 7). This characteristic can also be seen in Turborotalita humilis (Brady), 1884. The blunt pustules on the umbilical side of the early chambers surround the deeply set openings of pores. The pustules seem to be composite formations. Peripherally large isolated pustules produce a
finely and irregularly denticulate outline, typical of turborotalitids.

The maximum diameter of the holotype is about 125 microns; its axial height about 75 microns. The specimen coils to the right. It is from Hole 64.1, Core 7, Section 2, 33-35 centimeters, Zone N. 3 and is illustrated on pi. 26, fig. 7.

Turborotalita primitiva, n. sp., is the oldest turborotalitid from which Turborotalita humilis possibly derived. Turborotalita primitiva, n. sp., differs from Turborotalita humilis and from Turborotalita cristata (Heron-Allen and Earland), 1929, by the more tightly coiled trochospire, by the less lobate outline as seen in spiral view, by the less depressed sutures and by the smaller ultimate chamber, which does not extend over the umbilical depression into the cameral sutures.

Turborotalita primitiva possesses a single slit-like primary aperture whereas Turborotalita humilis and Turborotalita cristata develop multiple tunnel-like apertures in sutural positions. The final chamber has been called "bulla-like"" by Banner and Blow (1960,p. 36-37), however is in fact a normal chamber which simply extends over the umbilicus into the radial sutural depressions. These extensions are also shown in Blow's illustration (1969, p. 51, fig. 4) of an individual called Turborotalita cf. T. humilis (Brady) from Zone N. 17 (probably middle part), Kefallinia, Greece. We do not consider this chamber to be a homologue of a bulla as developed by adult individuals of Globigerinita. Blow (1969, p. 373) also referred Globigerina quinqueloba Natland, 1938, to the genus Turborotalita. This may be correct but needs corroboration.
Forms described by Parker (1967, pi. 18, fig. 13-14) as Globigerina cf. G. quinqueloba Natland, are without any doubt turborotalitids. Paratypes of Turborotalita primitiva from Core 7, Section 2 of Hole 64.1 show random coiling. The maximum diameter of paratypes ranges from about 100 to 125 microns. Several paratypes are illustrated on Plate 26 by scanning micrographs of the ventral side which show the same apertural features as were described for the holotype,and the same outer wall formations. According to Blow (1969, p. 373), the earliest turborotalitids occur within the lower parts of Zone N. 17. We have recognized forms referable to Turborotalita down in Zone N. 3,however, we did not distinguish them specifically on the range chart of Hole 64.1."

References:

Brönnimann, P. & Resig, J. (1971). A Neogene globigerinacean biochronologic time-scale of the southwestern Pacific. Initial Reports of the Deep Sea Drilling Project. 7(2): 1235-1469. gs O

Leckie, R. M., et al. (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene and Lower Miocene Paragloborotalia and Parasubbotina. 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 5): 125-178. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Turborotalita primitiva Brönnimann & Resig 1971

Turborotalita primitiva

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