Heterolepa broeckhiana ( Karrer, 1878 )

Bergh, Eugene W. & Compton, John S., 2022, Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf, Zootaxa 5091 (1), pp. 1-55 : 28

Heterolepa broeckhiana ( Karrer, 1878)

Pl. 6, figs. 3–4

Rotalina broeckhiana Karrer, 1878, p. 98 , pl. 5, fig. 26.

Gyroidina broeckhiana Belford, 1966 , pp. 167, 168, pl. 29, figs. 1–7, text-figs. 21–10, 21–11; Jones, 1994, p. 106, pl. 107, fig. 4.

Description: The test wall is calcareous and microperforate. The test is trochospiral, subcircular in outline and unequally biconvex in side view and in cross-section. Approximately six to eight chambers are visible externally in the final whorl. The chambers gradually increase in size toward the terminal apertural end and are separated by slightly depressed sutures. The sutures on the spiral side are radial and straight on the umbilical side. The aperture is an extraumbilical to interio-marginal slit.

Remarks: The relative abundances of this species are moderate to high (<10%) in the three cores. Tests in this study are relatively large, measuring up to 1 mm in diameter.

Life strategy: The genus Heterolepa has a shelf to upper slope distribution in well oxygenated environments (Rögl and Spezzaferri, 2003).

Regional occurrence: This study is the first to document this species in midddle Miocene strata in the region and occurs on the Namibian outer continental shelf, south of the Kunene River mouth (this study).