Heterolepa dutemplei ( 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 : 27-28

Heterolepa dutemplei ( d’Orbigny, 1846)

Pl. 6, figs. 2a–c

Rotalina dutemplei d’Orbigny, 1846, p. 157 , pl. 8, figs. 19–21.

Heterolepa dutemplei Papp & Schmid, 1985, p. 61 , pl. 52, figs. 1–6; Loeblich & Tappan, 1988, p. 632, pl. 709, figs. 1–8; Oblak, 2007, p. 305, pl. 4, figs. 2a–c; Holbourn et al., 2013, p. 294 –295.

Cibicidoides dutemplei van Morkhoven et al., 1986, p. 112 , pl. 35.

Description: The test wall is calcareous and macroperforate. The test is trochospiral and mainly planoconvex in side view, with the umbilical side very convex. The earlier chambers form a slightly convex shape on the spiral side. The approximately eight chambers in the final whorl gradually increase in size toward the apertural end. The chambers are separated by flush, less perforate sutures, covering almost the entire earlier chambers of the inner whorl. The sutures on the spiral side are oblique. The aperture is an interio-marginal slit, extending along the inflated apertural chamber on the umbilical side.

Remarks: Heterolepa dutemplei is a minor (<5%) component in the samples of all three cores. Tests are relatively moderate to large in size, measuring up to 1 mm in diameter.

Life strategy: This species has a bathymetric distribution from the shelf to the upper slope ( van Marle, 1988; Holbourn e t al., 2013), adapted to muddy substrates in organic-rich environments and oxic to suboxic conditions (e.g., Debenay-Redois, 1997; Peryt, 2013; Rahiminejad et al., 2016; Roslim et al., 2019).

Global stratigraphic range: Heterolepa dutemplei has been documented in Palaeocene ( Stojanova and Petrov, 2014) to Recent strata (e.g., van Marle, 1988; Szarek e t al., 2006).

Regional occurrence: This study records Heterolepa dutemplei to occur in middle Miocene sediments on the outer continental shelf of Namibia, south of the Kunene River mouth.