Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf
Author
Bergh, Eugene W.
0000-0002-0765-4141
Marine Research Institute and Department of Geological Sciences, University of Cape Town, Private Bag X 3, Rondebosch, 7701, South Africa. & Department of Environmental and Geographical Sciences, University of Cape Town, Private Bag X 3, Rondebosch, 7701, South Africa; & Invertebrate palaeontology and Geology, Iziko South African Museum, P. O. Box 61, Cape Town 8000, South Africa. john. compton @ uct. ac. za; https: // orcid. org / 0000 - 0002 - 0765 - 4141
john.compton@uct.ac.za
Author
Compton, John S.
Marine Research Institute and Department of Geological Sciences, University of Cape Town, Private Bag X 3, Rondebosch, 7701, South Africa.
text
Zootaxa
2022
2022-01-12
5091
1
1
55
journal article
2636
10.11646/zootaxa.5091.1.1
51b42715-ddb1-4b4a-aad4-8be0f600a287
1175-5326
5840434
ABC8AF70-F691-4D07-8F20-70934642C8BC
Plectofrondicularia
sp. B
Pl. 2, figs. 1–2
Description:
The test wall is calcareous. The test is flat with a keeled periphery and biserial in the early stage, becoming uniserial as chambers are added. The later chambers are chevron-shaped. The side abruptly widens and curves where it narrows towards the apertural end. The initial stage protrudes more than the later stage chambers. The sutures are limbate and the aperture terminal, radial with projecting laminae fusing centrally.
Remarks:
The tests are large in size (up to
1 mm
in width and
3 mm
in length), in trace abundances (<1%) in all three cores.
The tests range between narrow (pl. 2, fig. 1) and broad (pl. 2, fig. 2). The tests are mostly broken and resemble
Frondicularia sagittula
in
Jones (1994
; pl. 65, fig. 23) and
Plectofrondicularia vaughani
in
Holbourn
et al.
(2013
, p. 422), but with a peripheral keel and the absence of a basal spine. In this study, the specimens have been classified as
Plectofrondicularia
based on the presence of a keeled margin (
Loeblich & Tappan, 1988
). The specimens in this study were not assigned to
P. vaughani
,
because of its broader peripheral keel and thicker, more pronounced proloculus.
Life strategy
:
Plectofrondicularia
spp.
have been documented to occur as infaunal and under suboxic conditions (
Pezelj
et al
., 2013
and references therein).
Regional occurrence:
This species occurs in middle Miocene sediments from the northern Namibian outer continental shelf, south of the
Kunene
River
mouth (this study).
Wefer
et al
. (1998)
recorded minor occurrences of
Plectofrondicularia
spp.
(
Plectofrondicularia
cf.
inaequalis
,
Plectofrondicularia
cf.
raricosta
and
Plectofrondicularia
cf.
semicosta
) in
late Miocene
to Pleistocene-aged sediments along the Namibian and southwestern South African slope. The highest abundances (<10%) were recorded along the northern Namibian slope (
Wefer
et al
., 1998
).