Cibicidoides ungerianus ( d’Orbigny, 1846 )

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

Cibicidoides ungerianus ( d’Orbigny, 1846)

Pl. 6, figs. 1a–c

Rotalina ungeriana d’Orbigny, 1846, p. 157 , pl. 8, figs. 16–18; Papp & Schmid, 1985, p. 60, pl. 51, figs. 7–11.

Description: The test surface is calcareous and perforate. The test is trochospiral, subcircular in outline and thinly biconvex in side view. The spiral and umbilical sides are coarsely perforate. The chambers in the final whorl gradually increase in size toward the apertural end. The test margin has a thick keel and the chambers are separated by thick sutures with the earlier chambers not clearly visible. The aperture is an interio-marginal slit extending onto the umbilical lip.

Remarks: This species is less abundant than C. pseudoungerianus in this study, forming minor (<5%) components in the samples. The tests are generally large, measuring up to approximately 1 mm in diameter.

This species differs from C. pseudoungerianus by its more macroperforate test surface, particularly on the umbilical side. Cushman (1922b) re-identified the figured specimen of Truncatulina ungeriana as Truncatulina pseudoungeriana (= Cibicidoides pseudoungerianus ). The chambers in the final whorl of C. ungerianus are more inflated, whereas the chambers in the final whorl of C. pseudoungerianus are lobulated, more tapered and flattened towards the margins.

Life strategy: Species of the genus Cibicidoides are generally unattached, epifaunal to shallow-infaunal under oxic conditions ( Pezelj et al., 2013 and references therein), preferring muddy substrates ( Murray, 1991).

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