Globocassidulina subglobosa ( Brady, 1881 )

Bergh, Eugene W. & Compton, John S., 2022, Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf, Zootaxa 5091 (1), pp. 1-55 : 22

Globocassidulina subglobosa ( Brady, 1881)

Pl. 4, figs. 9–10

Cassidulina subglobosa Brady, 1881, p. 60 ; Brady, 1884, p. 430, pl. 54, fig. 17; Barker, 1960, pl. 54, fig. 17.

Globocassidulina subglobosa LeRoy & Levinson, 1974, p. 14 , pl. 7, fig. 8; Tjalsma & Lohmann, 1983, p. 31, pl. 16, fig. 9; Lowry, 1987, p. 239, pl. 14, figs. 7a–c; Miller & Katz, 1987, p. 134, pl. 3, fig. 4; Hermelin, 1989, p. 74; Thomas, 1990, p. 590; Jones, 1994, p. 60, pl. 54, fig. 17; Robertson, 1998, p. 136, pl. 53, figs. 1–2; Kuhnt et al., 2002, p. 144, pl. 10, figs. 3–5; pl. 17, figs. 1–2; Kender et al., 2008, p. 512, pl. 17, fig. 1–2; Milker & Schmiedl, 2012, p. 85, figs. 20.13–20.14; Holbourn et al., 2013, p. 264.

Description: The test wall is calcareous and smooth. The test is small, subglobular and subcircular in cross-section. The chambers have a biserial arrangement, are inflated and globular in shape, separated by depressed sutures. The aperture is slit-like, situated interio-marginal and stretches along the margin of the terminal chamber.

Remarks: Specimens from this species comprise a trace component (<1%) in core 2658, a minor component (<5%) in core 2682 and major component (<40%) in core 2670. The tests from this study are smaller than those in LeRoy & Levinson (1974) (diameter of up to 0.75 mm), measuring 0.25 mm in diameter.

Life strategy: This species is epifaunal to shallow-infaunal ( Kaiho, 1994; Vilela, 1995), generally unattached and prefers muddy sediments under oxic ( Kaiho, 1994) to suboxic ( De & Gupta, 2010) conditions. Schmiedl et al. (1997) recorded G. subglobosa in oligotrophic areas, under vigorous bottom currents and sandy substrates. Panieri & Gupta (2008) recorded this species in relatively high abundances in muddy substrates. The bathymetric range of G. subglobosa is broad, stretching from the middle shelf to abyssal depths ( Murgese & de Deckker, 2005; Holbourn et al., 2013).

Global stratigraphic range: Globocassidulina subglobosa occurs from the Palaeocene to Recent ( Holbourn et al., 2013).

Regional occurrence: This species is recorded in Miocene-aged strata from the Congo Basin ( Kender et al., 2008) and the Namibian outer continental shelf, south of the Kunene River mouth (this study). Hay et al. (1984) and Wefer et al. (1998) reported the occurrence of Globocassidulina subglobosa in late Miocene to Pleistoceneaged sediments along the continental slope in relatively minor abundances (<10%) at most sites. Lowry (1987) recorded occurrences of G. subglobosa in surface sediments on the continental shelf, between Cape Town and Port Elizabeth.