Globigerinoides subquadratus Bronnimann 1954

• Main Authors: Bergh, Eugene W., Compton, John S.
• Format: Text
• Language: unknown
• Published: Zenodo 2022
• Subjects: Biodiversity; Taxonomy; Chromista; Foraminifera; Globothalamea; Rotaliida; Globigerinidae; Globigerinoides; Globigerinoides subquadratus; Kennett; Moberly; Pacific; Saunders; Planktonic foraminifera
• Online Access: https://dx.doi.org/10.5281/zenodo.5842076; https://zenodo.org/record/5842076

Globigerinoides subquadratus Brönnimann, 1954 Pl. 7, figs. 11–12 Globigerinoides subquadratus Brönnimann, 1954, p. 680, pl. 1, fig. 8; Kennett & Srinivasan, 1983, p. 74, pl. 10, fig. 4; pl. 16, figs. 1–3. Description : The wall surface is macroperforate and cancellate-spinose. The test is trochospiral, sub-globular to sub-quadrate in shape and semi-circular in cross section. The chambers are sub-rounded to sub-quadrate in shape, with two basal chambers on the umbilical side, separated by a straight deep incised suture, which is overarched by a large chamber. The final chamber comprises approximately half the size of the test. The primary aperture is large and forms an arch symmetrically above the two basal chambers in apertural view. Two supplementary apertures form on the spiral side of the test along sutures of earlier chambers. Remarks: The relative abundances of Gs. subquadratus are major (<25%) in samples along the Mio-Pliocene contact of all three cores, increasing in abundance in the deeper cores. The tests of Gs. subquadratus are relatively small, measuring 0.3 mm in diameter. This species is very similar to Globigerinoides ruber ,but are stratigraphically separate and can be morphologically differentiated. Gs. subquadratus is identified in the Miocene, whereas Gs. ruber is extant and occurs in younger strata. Morphologically, the shape and outline of the test and chambers of Gs. subquadratus is more quadrate in shape compared to Gs. ruber (Bolli et al., 1985). Environmental preferences: Gs. subquadratus is associated with Neogene tropical environments (Brönnimann et al., 1971; Wade et al., 2011). Global stratigraphic range : This species occurs in Miocene strata from the Aquitanian to Tortonion (Kennett & Srinivasan, 1983; Wade et al., 2011). Regional occurrence: Gs. subquadratus has been identified in middle Miocene strata from the Congo Basin (Kender et al., 2008) and the northern Namibian outer continental shelf, south of the Kunene River mouth (this study). : Published as part of Bergh, Eugene W. & Compton, John S., 2022, Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf, pp. 1-55 in Zootaxa 5091 (1) on page 33, DOI: 10.11646/zootaxa.5091.1.1, http://zenodo.org/record/5840434 : {"references": ["Bronnimann, P. (1954) Probable occurrence of Oligocene on Saipan. American Journal of Science, 252 (11), 673 - 682. https: // doi. org / 10.2475 / ajs. 252.11.673", "Kennett, J. P. & Srinivasan, M. S. (1983) Neogene Planktonic Foraminifera. A Phylogenetic Atlas. Hutchinson Ross, Stroudsburg, 265 pp.", "Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (1985) Plankton Stratigraphy. Cambridge University Press, Cambridge, 1032 pp.", "Bronnimann, P., Martini, E., Resig, J., Riedel, W. R., Sanfilippo, A. & Worsley, T. (1971) Biostratigraphic synthesis: Late Oligocene and Neogene of the western tropical Pacific. In: Winterer, E. L., Riedel, W. R., Bronnimann, P., Gealy, E. L., Heath, R., Kroenke, L., Martini, E., Moberly, R., Resig, J. & Worsley, T. (Eds.), Initial Reports of the Deep Sea Drilling Project. Vol. 7. Ocean Drilling Program, College Station, Texas, pp. 1723 - 1745. https: // doi. org / 10.2973 / dsdp. proc. 7.136.1971", "Wade, B. S., Pearson, P. N., Berggren, W. A. & Palike, H. (2011) Review and revision of Cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale. Earth-Science Reviews, 104, 111 - 142. https: // doi. org / 10.1016 / j. earscirev. 2010.09.003", "Kender, S., Kaminski, M. A. & Jones, R. W. (2008) Early to middle Miocene foraminifera from the deep-sea Congo Fan, offshore Angola. Micropalaeontology, 54, 477 - 568."]}