Astacolus crepidula ( Fichtel & Moll, 1798 )

Bergh, Eugene W. & Compton, John S., 2022, Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf, Zootaxa 5091 (1), pp. 1-55 : 18

Astacolus crepidula ( Fichtel & Moll, 1798)

Pl. 3, fig. 4

Nautilus crepidula Fichtel & Moll, 1798, p. 107 , pl. 19, fig. g–i.

Cristellaria crepidula Cushman, 1923a , p. 117, pl. 35, fig 3–4.

Lenticulina crepidula Sandidge, 1932, p. 346 , pl. XXXII, fig. 6.

Astacolus crepidulus Barker, 1960 , pl. 67, fig. 20, pl. 68, fig. 1–2; Lowry, 1987, p. 149, pl. 8, fig. 3; Loeblich & Tappan, 1994, p. 72, pl. 130, fig. 1–20; Jones, 1994, p. 80, pl. 68, fig. 1–2.

Description: The test wall is calcareous, smooth and finely perforate. The test is compressed and some specimens are nearly three times longer than broad. Up to seven chambers increase in size toward the apertural end and the slightly depressed sutures are oblique, with the angle between the suture and base of the test increasing as chambers are added. The radiate aperture protrudes at the terminal end of the test.

Remarks: Specimens are moderate in size, measuring up to 0.5 mm in width and 1 mm in length. The figured specimen in Sandidge (1932) is 1.2 mm in length. The relative abundance is generally low, forming trace components (<1%) in some of the samples in core 2670.

Life strategy: This species is infaunal, adapted to a wide range of oxygen conditions ( Kaminski, 2012).

Global stratigraphic range: Jones (1994) reported Astacolus crepidula to occur from the Miocene to Recent, but Cushman (1923a) extends it back to the Cretaceous.

Regional occurrence: This species occurs in middle Miocene sediments on the Namibian outer continental shelf, south of the Kunene River mouth (this study) and in Recent sediments off Cape Agulhas, South Africa ( Lowry, 1987).