Paragloborotalia incognita


Classification: pf_cenozoic -> Globigerinidae -> Paragloborotalia -> Paragloborotalia incognita
Sister taxa: P. acrostoma, P. incognita, P. pseudocontinuosa, P. semivera, P. kugleri, P. pseudokugleri, P. mayeri, P. siakensis, P. birnageae, P. continuosa, P. opima, P. nana, P. griffinoides, P. sp.,

Taxonomy

Citation: Paragloborotalia incognita (Walters 1965)
Rank: species
Basionym: Globorotalia zealandica incognita Walters 1965
Synonyms:
Taxonomic discussion:

Kennett and Srinivasan (1983) consider incognita to be the senior synonym of pseudocontinuosa. Following Cifelli and Scott (1983), we consider P. incognita to be a valid transitional taxon between P. pseudocontinuosa and Globoconella zealandica. [Leckie et al. 2018]

Gr. (G.) incognita differs from its ancestor "Gr. " nana in having a higher arched aperture. It is distinguished from its descendant Gr. (G.) zealandica by its smaller size, more strongly curved spiral sutures, and much less inflated umbilical side. Gr. (G.) incognita differs from Neogloboquadrina continuosa in exhibiting a more rapid increase in chamber size, in being more compact, and in having a higher arched aperture extending farther up onto the apertural face. [Kennett & Srinivasan 1983]

Catalog entries: Globorotalia zealandica incognita

Type images:

Distinguishing features:

Like P. nana but larger, and with a more rapid rate of chamber expansion, a less compact test, a higher arched aperture, elongation of the chambers in the direction of coiling, and slightly curved spiral sutures.

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.
They are being edited as the site is developed and comments on them are especially welcome.

Description


Diagnostic characters:

This species is distinguished from P. nana by its larger size, and in having a more rapid rate of chamber expansion, a less compact test, a higher arched aperture, elongation of the chambers in the direction of coiling, and slightly curved spiral sutures. It is distinguished from P. opima in having a distinctly more higher arched aperture, and asymmetrical final chamber. The species had been synonymized with P. pseudocontinuosa (e.g., Li and others, 1992), but can be differentiated by the more extraumbilical aperture, flatter spiral side with slightly curved spiral-side sutures, and subspherical final chamber in axial profile (edge view). Paragloborotalia incognita is distinguished from P. continuosa by having a larger, more inflated, but subspherical final chamber, slight chamber elongation, and slightly curved spiral sutures. It is distinguished from G. zealandica pseudomiozea Walters in having a distinctly more cancellate wall, more rounded periphery, and a less flattened spiral side. [Leckie et al. 2018]


Wall type: Normal perforate, coarsely cancellate, unclear if spinose in life, heavy gametogenetic calcification is often present. [Leckie et al. 2018]

Test morphology: Test medium to large in size; low trochospiral, quadrate and lobulate in equatorial outline, chambers spherical to subspherical, inflated, embracing; typically 4, occasionally 4½ chambers in ultimate whorl, increasing rapidly in size; may possess small kummerform final chamber or chamberlet; in spiral view chambers weakly inflated, longer than broad in the direction of coiling, arranged in 2½-3 whorls, sutures slightly depressed, slightly curved; in umbilical view chambers moderately inflated, sutures slightly depressed, radial to slightly curved, umbilicus narrow, shallow; aperture umbilical-extraumbilical, moderately high arch, bordered by a narrow, thickened, continuous lip; in edge view chambers subspherical, spiral side nearly flat, umbilical side more strongly convex, periphery broadly rounded. [Leckie et al. 2018]

Size: Maximum diameter of holotype 0.36 mm; maximum thickness 0.23 mm (original measurements); diameter 0.35 mm; thickness 0.23 mm (remeasured this study). [Leckie et al. 2018]

Character matrix

test outline:Ovatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical-extraumbilical
sp chamber shape:Globularcoiling axis:Lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Weakly depressedumb depth:Shallowwall texture:Cancellateshell porosity:Macroperforate: >2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:4.0-4.5 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Cool temperate waters in mid to high latitudes, nearly all recorded occurrences are between 30o-60oS in the South Atlantic and South Pacific Ocean (e.g., Berggren and others, 1983; Jenkins, 1971, 1978; Morgans and others, 2002). In addition, Keller (1981) reported incognita from the equatorial and northwest Pacific Ocean. [Leckie et al. 2018]

Isotope paleobiology: No data available. [Leckie et al. 2018]

Phylogenetic relations: Paragloborotalia incognita is transitional in morphology between ancestral P. pseudocontinuosa and the G. zealandica lineage (Cifelli and Scott, 1983), including G. pseudomiozea, following Berggren and others (1983). Paragloborotalia incognita evolved from P. pseudocontinuosa in the earliest Miocene (Subzone M1a). [Leckie et al. 2018]

Most likely ancestor: Paragloborotalia pseudocontinuosa - at confidence level 4 (out of 5). Data source: Leckie et al. 2018.
Likely descendants: Globorotalia zealandica;

Biostratigraphic distribution

Geological Range:
Notes: Lower Miocene Subzone M1a (Spezzaferri, 1994) or M1b (Keller, 1981; Berggren and others, 1983; Cifelli and Scott, 1983; Berggren, 1992; Harwood and others, 1992) to Zone M3 (Barron and others, 1991; Huber, 1991; Berggren, 1992; Harwood and others, 1992; Spezzaferri, 1994; Ali and Vandamme, 1998); the range may extend into the middle Miocene at high latitudes. Morgans and others (2002) report a LAD of P. incognita in Chron C5En. [Leckie et al. 2018]
Last occurrence (top): within M3 zone (17.54-19.30Ma, top in Burdigalian stage). Data source: Leckie et al. 2018
First occurrence (base): within M1 zone (21.12-22.96Ma, base in Aquitanian stage). Data source: Leckie et al. 2018

Plot of occurrence data:

Primary source for this page: Leckie et al. 2018 - Olig Atlas chap.5 p.140; Kennett & Srinivasan 1983, p.106

References:

Ali, J. R. & Vandamme, D. (1998). Eocene–Miocene magnetostratigraphy of the southeast Greenland margin and western Irminger Basin. Proceedings of the Ocean Drilling Program, Scientific Results. 152: 253-257. gs

Aze, T. et al. (2011). A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data. Biological Reviews. 86: 900-927. gs

Barron, J. A. et al. (1991). Biochronologic and magnetochronologic synthesis of Leg 119 sediments from the Kerguelen Plateau and Prydz Bay, Antarctica. Proceedings of the Ocean Drilling Program, Scientific Results. 119: 813-847. gs

Berggren, W. A. (1992). Paleogene planktonic foraminifer magnetobiostratigraphy of the southern Kerguelen Plateau (sites 747-749). Proceedings of the Ocean Drilling Program, Scientific Results. 551-568. gs

Berggren, W. A., Aubry, M. -P. & Hamilton, N. (1983). Neogene magnetobiostratigraphy of DSDP Site 516, Rio Grande Rise (South Atlantic). Initial Reports of the Deep Sea Drilling Project. 72: 675-713. gs

Cifelli, R. & Scott, G. H. (1983). The New Zealand early Miocene globorotaliids Globorotalia incognita Walters and Globorotalia zealandica Hornibrook. Journal of Foraminiferal Research. 13: 163-166. gs

Cifelli, R. & Scott, G. H. (1986). Stratigraphic record of the Neogene globorotaliid radiation (Planktonic Foraminiferida). Smithsonian Contributions to Paleobiology. 58: 101-. gs

Harwood, D. M. et al. (1992). Neogene integrated magnetobiostratigraphy of the central Kerguelen Plateau, Leg 120. Proceedings of the Ocean Drilling Program, Scientific Results. 120: 1031-1052. gs

Huber, B. T. (1991c). Paleogene and Early Neogene Planktonic Foraminifer Biostratigraphy of Sites 738 and 744, Kerguelen Plateau (Southern Indian Ocean). Proceedings of the Ocean Drilling Program, Scientific Results. 119: 427-449. gs

Jenkins, D. G. (1971). New Zealand Cenozoic Planktonic Foraminifera. New Zealand Geological Survey, Paleontological Bulletin. 42: 1-278. gs

Keller, G. (1981). Origin and evolution of the genus Globigerinoides in the Early Miocene of the northwestern Pacific, DSDP Site 292. Micropaleontology. 27(3): 293-304. gs

Kennett, J. P. & Srinivasan, M. S. (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. gs

Leckie, R. M. et al. (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene and Lower Miocene Paragloborotalia and Parasubbotina. In, Wade, B. S. , Olsson, R. K. , Pearson, P. N. , Huber, B. T. & Berggren, W. A. (eds) Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 46(Chap 5): 125-178. gs

Li, Q., Radford, S. S. & Banner, F. T. (1992). Distribution of microperforate tenuitellid planktonic foraminifers in Holes 747A and 749B, Kerguelen Plateau. Proceedings of the Ocean Drilling Program, Scientific Results. 120: 569-594. gs

Morgans, H. E. G. et al. (2002). Integrated stratigraphy of the lower Altonian (early Miocene) sequence at Tangakaka Stream, East Cape, New Zealand. New Zealand Journal of Geology and Geophysics. 45: 145-173. gs

Spezzaferri, S. (1994). Planktonic foraminiferal biostratigraphy and taxonomy of the Oligocene and lower Miocene in the oceanic record. An overview. Palaeontographia Italica. 81: 1-187. gs

Tjalsma, R. C. (1977). Cenozoic Foraminifera from the South Atlantic, DSDP Leg 36. Initial Reports of the Deep Sea Drilling Project. 36: 493-518. gs

Walters, R. (1965). The Globorotalia zealandica and G. miozea lineages. New Zealand Journal of Geology and Geophysics. 8: 109-127. gs


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Paragloborotalia incognita compiled by the pforams@mikrotax project team viewed: 12-12-2019

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