Globigerina concinna Reuss, 1850

Bergh, Eugene W. & Compton, John S., 2022, Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf, Zootaxa 5091 (1), pp. 1-55 : 32

Globigerina concinna Reuss, 1850

Pl. 7, figs. 7-8

Globigerina concinna Reuss, 1850, p. 373 , pl. 47, fig. 8; Cushman and Stainforth, 1945, pl. 13, fig. 1; Bolli et al., 1985, p. 321, fig. 4.17–20.

Description: The wall surface is cancellate spinose. The test is trochospirally arranged, with five globular chambers in the final whorl. The sutures are straight and depressed. The aperture is large and umbilical.

Remarks: The relative abundance of G. concinna in this study is trace (<1%) in samples of all three cores. The tests are relatively moderate in size, measuring up to 0.5 mm in diameter.

This species is similar to an older form, Ciperoella ciperoensis (previously Globigerina ciperoensis ), but differs in its size, chambers and aperture. The chambers of G. concinna increase in size more rapidly and its test is generally larger compared to C. ciperoensis . The aperture of G. concinna is also larger and more asymmetrical than C. ciperoensis . The two species, furthermore, occur in different stratigraphic ranges. C. ciperoensis occurs in the Oligocene, whereas G. concinna occurs in middle Miocene strata ( Bolli et al., 1985).

Environmental preferences: Species in the G. concinna group is regarded to be adapted to tropical and subtropical conditions ( BouDagher-Fadel, 2015).

Global stratigraphic range: G. concinna has been documented to occur from the Burdigalian in the early Miocene to the Serravallian in the middle Miocene ( BouDagher-Fadel, 2015).

Regional occurrence: This study records the first, and to date, only occurrence in the region of this species in the middle Miocene of the northern Namibian continental shelf, south of the Kunene River mouth (this study) .