Catalog - Globigerinita boweni

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Globigerinita boweni

Citation: Globigerinita boweni Brönnimann & Resig 1971

Type age (chronostrat): Oligocene

Type locality: South West Pacific, Ontong Java Plateau or Soloman Rise New Guinea: DSDP Leg 7, Hole 64.1

Type repository: Washington; USNM

The very small-sized test is a high trochospire of about 12 chambers with four chambers that gradually increase in size in the final whorl and an umbilically situated bulla opening toward the penultimate chamber. The subglobular bulla of 50 microns maximum diameter has an opening of about 20 microns maximum diameter. It rests on the ultimate, ante-penultimate and ante-antepenultimate chambers. The initial portion of the trochospire is not pointed. The subglobular chambers of the final whorl are separated on umbilical and spiral sides by well-depressed, radial, cameral sutures. Also the spiral suture is distinct. In spiral and umbilical view, the outline is lobate and inside view bluntly convex on the spiral side. On the umbilical side, the broadly rounded bulla protrudes slightly in side view. Without bulla, the umbilical side is
virtually flat. The primary aperture, which is umbilical,can be seen through the opening of the bulla. It is a small arched opening with a distinct narrow border of granular appearance. The apertural margin of the bulla, on the other hand, is not thickened nor separated from the bulla wall but is irregularly pustulate and faintly up-turned. The umbilicus is shallow and broad. The calcareous wall of the normal chambers is thin, finely perforate, and the surface is pustulate. The pustules are largest on the umbilical sides of the chambers, densely set, blunt to pointed distally as shown by the scanning micrographs (Plate 26, Figures 2 and 4), and in between the densely set pustules minute openings of the perforations are discernible. In places it seems that the large rounded pustules are interconnected by radiating thin walls, and in between these connections open the wall pores. In fact these minute openings seem to surround the pustules not vice versa as described for most Globigerinacea, and there is no sign of a polygonal meshwork. The pustules are composites of
minute elements. The bulla is very thin-walled and very finely pustulate and perforate.

The maximum diameter of the holotype is about 130 microns; its axial height is about 100 microns. The specimen coils to the left. It is from Hole 64.1, Core 7, Section 2, 33-35 centimeters; Zone N. 3. It is illustrated on Plate 26, Figure 1. The species is named for Dr. Vaughan Bowen, Woods Hole Oceanographic Institution, Woods Hole,Massachusetts, U.S.A.

By the lower trochospire, the low and arched primary aperture and the single-aperture umbilical bulla Globgerinita boweni, n. sp., differs from the equally small but high trochospires of Globigerinita uvula (Ehrenberg) from Hole 62.1 and of Globigerinita aff.Globigerinita uvula (Ehrenberg) from Hole 64.1 Globigerinita uvula is normally a much higher tro-chospire of about 3 or more whorls, with 5, occasionally 4 chambers in the final whorl and, as shown by the scanning micrographs, Plate 22, Figures 7 and 8,possesses a brilliant, finely to coarsely pustulate wall.

The bulla of uvula is much more flattened than that of Globigerinita boweni, usually with apertures at the intersection of the bulla with the cameral sutures of the final whorl. Furthermore, the principal aperture is much larger than that of Globigerinita boweni, n. sp., but also is provided with a distinct rim. Parker (1962,pi. 8, fig. 14-26; 1967, pi. 17, fig. 8 and 9) has well illustrated Globigerinita uvula which was recorded in most samples from N. 17 to N. 23, Globigerinita aff.Globigerinita uvula from Hole 64.1 is closer to Globigerinita boweni than to Globigerinita uvula. The affine form occurs in Hole 64.1 from Core 1 to 7, that is from Zones N. 7/N. 8 to N. 3. Paratypes of Globigerinita boweni, n. sp., from Core 7, Section 2,Hole 64.1, coil randomly. The maximum diameter of paratypes across the final whorl ranges from about 100
to 150 microns. A remarkable feature of the outer wall formations is the absence of the polygonal meshwork.

References:

Brönnimann, P. & Resig, J. (1971). 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. Initial Reports of the Deep Sea Drilling Project. 7(2): 1235-1469. gs O

Pearson, P. N., Wade, B. S. & Huber, B. T. (2018c). Pearson, P. N., Wade, B. S. & Huber, B. T. (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene Globigerinitidae (Dipsidripella, Globigerinita, and Tenuitella). 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 16): 429-458. 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 16): 429-458. gs O

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerinita boweni Brönnimann & Resig 1971

Globigerinita boweni

References:

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