Hansenisca soldanii ( d’Orbigny, 1826 )

Bergh, Eugene W. & Compton, John S., 2022, Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf, Zootaxa 5091 (1), pp. 1-55 : 29-30

Hansenisca soldanii ( d’Orbigny, 1826)

Pl. 6, figs. 8a-b; pl. 7, figs. 1a–c

Gyroidina soldanii d’Orbigny, 1826, p. 278 ; d’Orbigny, 1846, pl. 8, figs. 10–12; Papp & Schmid, 1985, p. 60, pl. 50, figs. 4–9. Gyroidinoides soldanii Lowry, 1987, p. 254 , pl. 15, figs. 9a–b; Jones, 1994, p. 106, pl. 107, figs. 6–7; Kender et al., 2008, p.

519, pl. 25, figs. 1–5; Holbourn et al., 2013, p. 278.

Description: The test wall is calcareous and microperforate. The test is trochospiral and planoconvex to slightly unequally biconvex in side view. The spiral side is flat to slightly convex and the umbilical side highly convex. The approximately eight chambers in the final whorl gradually increase in size toward the apertural end and are separated by slightly depressed straight sutures. The sutures are radial on the spiral side and straight on the umbilical side. The umbilical sutures may be faint to slightly visible. The aperture is an interio-marginal slit, produced on a flap of the terminal chamber, extending onto the umbilical region.

Remarks: This species occurs in minor to moderate abundances in the cores. The tests are moderately large, measuring up to 0.9 mm in diameter.

Life strategy: This species is epifaunal to shallow-infaunal ( Pérez-Asensio et al., 2012), suboxic, unattached, preferring muddy substrates ( Murray, 1991) on the slope ( Holbourn et al., 2013).

Global stratigraphic range: Hansenisca soldanii occurs from the Oligocene to Recent ( Jones, 1994).

Regional occurrence: Kender et al. (2008) reported H. soldanii (= Gyroidinoides soldanii ) from the Miocene in the Congo Basin. This study extends the spatial distribution of the species to the middle Miocene of the outer continental shelf of Namibia, south of the Kunene River mouth. This species also occurs in minor (<1%) to moderate (<50%) abundances along the slope of Namibia and southwestern South Africa from the late Miocene to Pleistocene. The highest abundances were recorded on the slope between Walvis Bay and Lüderitz, Namibia ( Wefer et al., 1998). Lowry (1987) reported H. soldanii in surface sediments off the coast of northern Namibia to around the entire coastline of South Africa.