Grigelis semirugosus ( 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 : 10

Grigelis semirugosus ( d’Orbigny, 1846)

Pl. 1, fig. 15

Nodosaria pyrula d’Orbigny, 1826, p. 253 , fig. 13.

Nodosaria semirugosa d’Orbigny, 1846, p. 34 , pl. 1, fig. 20–23; Papp & Schmid, 1985, p. 24, pl. 4, figs. 6–8.

Grigelis semirugosa Jones, 1994, p. 75 , pl. 63, figs. 23–27.

Description: The wall is calcareous, hyaline. The test is elongate, uniserial and semi-circular in cross section. The chambers are rounded and oval in shape.A tubular neck separates each chamber from the next. Ridges are prominent on the base of each chamber. The rounded aperture is terminal at the end of a long thin neck.

Remarks: Few specimens of this species were recorded, comprising <1% of the total foraminiferal assemblage in core 2670. Tests are long, measuring 0.25 mm in cross-section and up to 3 mm in length.

Life strategy: Species of the genus Grigelis are infaunal, under suboxic conditions ( Pezelj et al., 2013).

Global stratigraphic range: This species is recorded to occur from the Miocene to Recent ( Jones, 1994).

Regional occurrence: Grigelis semirugosus occurs in middle Miocene sediments on the Namibian outer continental shelf, south of the Kunene River mouth (this study).