Cibicidoides pseudoungerianus ( Cushman, 1922b )

Bergh, Eugene W. & Compton, John S., 2022, Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf, Zootaxa 5091 (1), pp. 1-55 : 26-27

Cibicidoides pseudoungerianus ( Cushman, 1922b)

Pl. 5, figs. 8–10

Truncatulina ungeriana Brady, 1884, p. 664 , pl. 94, fig. 9.

Truncatulina pseudoungeriana Cushman, 1922b, p. 96 , pl. 10, fig. 9.

Cibicides pseudoungeriana Cushman, 1931, p. 123 , pl. 22, figs. 3–7.

Cibicidoides pseudoungerianus Cimerman & Langer, 1991, p. 69 , pl.74, fig. 2–3; Milker & Schmiedl, 2012, p. 103, fig.24.5– 24.9.

Cibicides pseudoungerianus Barker, 1960 , pl. 94, fig. 9; Lowry, 1987, p. 322, pl. 21, figs. 3a–c; Milker et al., 2009, p. 218, pl. 3, fig.11.

Description: The test wall is calcareous and perforate. The test is trochospiral, subcircular in outline and unequally biconvex in side view and in cross-section. The spiral side is coarsely perforate and the umbilical side is smoother. The umbilical side is more convex than the spiral side. The approximately ten chambers in the final whorl gradually increase in size toward the apertural end. The earlier chambers are not visible on the spiral side, as the test wall is thickened in the central part of the test. The chambers are separated by flush, thick sutures. The sutures on the spiral side are oblique, whereas sutures on the umbilical side radiate from a thick central umbo. The aperture is interiomarginal, bordered by a thin lip.

Remarks: The relative abundances of C. pseudoungerianus decrease toward the deeper cores, forming major (<20%) to minor (<5%) components in the samples of all three cores. Tests of this species in this study are moderate in size, measuring up to 0.6 mm in diameter.

This species differs from C. ungerianus by its smoother test surface and the hidden earlier chambers on the spiral side. Cushman (1922b) re-identified the figured specimen of Truncatulina ungeriana as Truncatulina pseudoungeriana (= Cibicidoides pseudoungerianus ), based on the similarities with those illustrated in Cushman (1922b). The specimens from this study resemble those in Brady (1884) and Cushman (1922b), in its thickened central portion and finer, smoother test wall, compared to C. ungerianus .

Life strategy: Cibididoides pseudoungerianus is an epifaunal to shallow-infaunal species, adapted to oxic bottom water conditions ( Murgese & de Deckker, 2005; Murray, 2006). This species is documented to have shelf to slope distributions, but more typical of upper slope environments ( Murgese & de Deckker, 2005).

Global stratigraphic range: Cibididoides pseudoungerianus occurs in Oligocene to Recent strata ( Jones, 1994).

Regional occurrence: This species is recorded in middle Miocene sediments on the Namibian outer continental shelf, south of the Kunene River mouth (this study).