Catalog - Globigerina brevis

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Globigerina brevis

Citation: Globigerina brevis Jenkins 1966

Type specimens: TF 1498: holotype and 3 paratypes.

Type age (chronostrat): lower part of Whaingaroan Stage (Lower Oligocene).

Type locality: S136/694, F 9398, grid ref. 482554, Sheet S136 (edit. 1943), Kakanui River, south bank near mouth, 2 ft 6 in. above bored surface, calcareous glauconitic fine-grained sandstone. Collected by M. Gage.

Type repository: Lower Hutt, New Zealand; New Zealand Geological Survey

Test free, low trochospiral, dextrally coiled,equatorial periphery quadrilobate, axial periphery rounded.
Wall calcareous,perforate with a coarse-reticulate sub-hexagonal pattern, thickened reticulate ridges developed on the umbilical side of the anti-penultimate and penultimate chambers just outside the aperture.
Chambers with spherical outline,13 arranged in about 3, whorls, with 5 in the! first, 4 in the second and last whorls; chambers of the final whorl increasing slowly in size; proloculus diameter about 0.02 mm.
Sutures on the spiral side slightly curved to radial, slightly depressed; umbilical side sutures radial, depressed, and well marked. Umbilicus narrow, deep. Aperture a low arch, interiomarginal,umbilical.

REMARKS: Globigerina brevis n. sp. is a distinctive short-ranging species in the New Zealand uppermost Runangan to lower Whaingaroan rocks. The type population exhibits a wide variation in test morphology. The final test chamber varies in size from larger than the penultimate to a small bulla-like structure that tends to obscure the primary umbilical aperture (Nos. 61, 62). Some specimens are thick walled with deeply incised umbilical sutures (No. 63).
Coiling is nearly random, with 76 dextral and 71 sinistral specimens in the type sample. The only other species resembling G. brevis is Globigerina tripartita tapuriensis Blow and Banner from the Oligocene of the Lindi area, Tanganyika (in Eames et ai., 1962), but G. brevis differs in having a smaller test and a more coarsely ornamented and non-hispid wall and more deeply incised umbilical sutures.
The specific name is taken from the Latin brevis and refers to the short stratigraphic range.

The article was published in the December 1965 issue of the journal but appeared in early 1966, so for taxonomy the correct date is 1966.

Subspherical chambers coiled in a moderately high trochospire, oval in outline, 13 chambers arranged in 3 whorls, increasing slowly in size, umbilical sutures radial, deeply incised, spiral sutures weakly depressed, aperture umbilical, deep. Maximum diameter of holotype 0.44 mm. [Berggren & Wade 2018]

This species was described from the lower Oligocene, though it ranges from the upper Eocene to the lower Oligocene, with extinction prior the Subbotina angiporoides last appearance datum (Jenkins, 1965). Jenkins (1985) considered this to be a useful biostratigraphic species in high latitudes ranging across the Eocene-Oligocene Transition, with a short stratigraphic range, hence the name brevis. Through our investigations, we have been unable to determine the taxonomic assignment of Globigerina brevis. Jenkins (1965) did state that the population of this species exhibits a wide variation in test morphology. The new SEMs of both the holotype and paratype have not clarified the concept of this species. [Berggren & Wade 2018]

Jenkins (1985) discussed the similarity between brevis and tapuriensis Blow and Banner. Based on the wall texture we do not consider this form to be affiliated with Dentoglobigerina, instead Globoturborotalita is a more likely affinity. This species has not been utilized by Oligocene workers, with the exception of Quilty (1976), who illustrated forms of cf. brevis which we consider to be more akin to Subbotina utilisindex. Huber (1991) illustrated a very cancellate form (pl. 5, fig. 8) which is likely to be a Globoturborotalita. [Berggren & Wade 2018]

There is some resemblance between brevis and paracancellata n. sp. Olsson and Hemleben (Chapter 8, this volume). However, brevis is more compact and tightly coiled than paracancellata, which is more lobulate and the ultimate chamber is more elevated. Globigerina brevis shows almost 4 chambers in umbilical view whereas paracancellata n. sp. shows 3 to nearly 3½ chambers. We have been unable to find forms consistent with G. brevis and therefore place this species in Problematica pending further investigations from high latitude sites. [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. gs

Jenkins, D. G. (1966b). Planktonic foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. New Zealand Journal of Geology and Geophysics. 8 [1965](6): 1088-1126. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina brevis Jenkins 1966

Globigerina brevis

References:

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