pforams@mikrotax - Parasubbotina varianta

Citation: Parasubbotina varianta (Subbotina 1953)

Synonyms:

Globigerina varianta Subbotina, 1953:63, holotype: pl. 3:fig.5a-c; paratypes: pl. 3: figs. 6a-7c, 10a-l lc [zone of rotaliform Globorotalia, Elburgan Fm., Kuban River section, northern Caucasus], pl. 3: fig. 12a-c [zone of compressed Globorotalia, base of lower White Series, Murzai-Tai, Mangyshlak Peninsula, southwestern Russia], pl. 4: figs. la-3c [zone of rotaliform Globorotalia, base Foraminiferal Layer Fl, Khieu River section, near Nal'chik, northern Caucasus] [in part, not pl. 3: figs. 7a-c, 8a-c, pl. 15: figs, la-c, 2a-c, 3a-c].
Globorotalia (Globorotalia) varianta (Subbotina).—Hillebrandt, 1962:125, pl. 12: figs. lOa-c, lla.b [Zone D, Reichenhall-Salzburg Basin, Austro-German border],
Globorotalia (Turborotalia) quadrilocula Blow, 1979:1109, holotype: pl. 87: fig. 7 [Zone P3, DSDP Hole 47.2/10/1: 72-74 cm], paratypes: pl. 75:fig.8 [Zone PI, Lindi, Tanzania], pl. 78: figs. 2-4 [Zone P2, DSDP Hole 20C/6/4: 72-74 cm; Brazil Basin, South Atlantic Ocean], pl. 83: fig. 3 [Zone P2, DSDP Hole 47.2/10/3: 78-80 cm; Shatsky Rise, northwestern Pacific Ocean], pl. 87:fig.8 [Zone PI, Lindi, Tanzania].
Subbotina varianta (Subbotina).—Berggren, 1992:563, pl. 1:fig.3 [ODP Hole 747A/19H/CC; southern Kerguelen Plateau, southern Indian Ocean].
Stainforth and Lamb, 1981:25, pl. 4, fig. 1a-c [upper Eocene, Atlantic Slope Project corehole 5B, western North Atlantic Ocean]. [Not Bolli, 1957.]

Taxonomic discussion:

The species is smaller and has fewer chambers in the ultimate whorl than does the closely related Parasubbotina pseudobulloides. Blow (1979) regarded P. varianta as an ecophenotypic variant of P. pseudobulloides comprising a rather specialized side branch of the pseudobulloides plexus. At the same time he erected the species Globorotalia (Turborotalia) quadrilocula, which he considered to have originated from a "four-chambered last-whorl variant" (Blow, 1979:1110) of pseudobulloides. The holotype of P. varianta (Plate 9: Figures 16-18) is a 4-chambered form with an ultimate chamber somewhat more inflated than Blow's concept of quadrilocula. We regard G. (T.) quadrilocula as falling within the morphologic range of variability of P. varianta. [Olsson et al. 1999]

Distinguishing features:
Parent taxon (Parasubbotina): Very low trochospiral test, chambers increasing rapidly in size; aperture high-arched umbilical-extraumbilical aperture. At most 5 chambers in final whorl.
This taxon: Test with 4 chambers in final whorl, rapidly expanding. Aperture umbilical-extraumbilical, a rounded high arch with fairly broad continuous lip. Umbilicus, small, rounded; deep and open to the surrounding chambers. Wall cancellate spinose with spine holes.

Description

Parasubbotina varianta is more loosely coiled and its chambers are less embracing than in P. griffinoides, leading to a more lobulate test. In P. griffinoides, the apertural lip is more uniform and constant in thickness than in P. varianta and other species of Parasubbotina. [Leckie et al. 2018]

Test very low trochospiral, globular, subquadrate in outline, chambers globular, much inflated, embracing; in spiral view 4, occasionally 4½ globular, embracing chambers in ultimate whorl, increasing rapidly in size, sutures slightly depressed, straight, last 4 chambers make up about three quarters of the test, ultimate chamber may be slightly reduced in size; in umbilical view 4, occasionally 4½ globular, embracing chambers, increasing rapidly in size, sutures slightly depressed, straight, umbilicus very small sized opening, sometimes closed off by surrounding chambers, aperture a high arch, umbilical-extraumbilical, bordered by a narrow, often thickened, continuous, lip, ultimate chamber may be slightly reduced in size; in edge view chambers globular, periphery rounded. [Leckie et al. 2018]

Normal perforate, coarsely cancellate, ruber/sacculifer-type, spinose. [Leckie et al. 2018]

Maximum diameter of holotype 0.41 mm, minimum diameter 0.39 mm, maximum width 0.29 mm. [Leckie et al. 2018]

Biogeography and Palaeobiology

Widespread in low and middle latitudes. [Leckie et al. 2018]

Parasubbotina varianta has a δ13C and δ18O signature similar to that of P. pseudobulloides, Subbotina triloculinoides, and Globanomalina compressa but typically with heavier δ18O and more negative δ13C than coexisting Praemurica and Morozovella. The species shows little change in δ18O or δ13C over a large size range. [Olsson et al. 1999]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light _¹³C and relatively heavy _¹⁸O. Sources cited by Aze et al. 2011 (appendix S3): Olsson et al. (1999); Pearson et al. (2001a).

Blow's (1979) observations on the close relationship of this species with P. pseudobulloides is supported by our observations. The species evolved in Zone Pic from P. pseudobulloides by a reduction in the number of chambers in the ultimate whorl and a tightening of the whorl. [Olsson et al. 1999]

Biostratigraphic distribution

Geological Range:
Notes: Parasubbotina varianta is a long ranging taxon that evolved in the Danian. We have identified this species from Zone O1 in records from the equatorial Pacific Ocean and US Gulf Coast Plain, thus extending its recorded range into the lowermost Oligocene. [Leckie et al. 2018]
Last occurrence (top): within O1 zone (32.10-33.90Ma, top in Rupelian stage). Data source: Leckie et al. 2018
First occurrence (base): within P1c subzone (62.60-63.90Ma, base in Danian stage). Data source: Olsson et al. 1999

Primary source for this page: Leckie et al. 2018 - Olig Atlas chap.5 p.170; Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 26

References:

Berggren, W. A. (1992). Berggren, W. A. (1992). Paleogene planktonic foraminifer magnetobiostratigraphy of the southern Kerguelen Plateau (sites 747-749). Proceedings of the Ocean Drilling Program, Scientific Results. 120: 551-568. Proceedings of the Ocean Drilling Program, Scientific Results. 120: 551-568. gs

Blow, W. H. (1979). Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. E. J. Brill, Leiden. 2: 1-1413. gs

Bolli, H. M. (1957a). Bolli, H. M. (1957). Planktonic foraminifera from the Eocene Navet and San Fernando formations of Trinidad. In, Loeblich, A. R. , Jr. , Tappan, H. , Beckmann, J. P. , Bolli, H. M. , Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 155-172. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 155-172. gs

Hillebrandt, A. , von (1962). Hillebrandt, A. , von (1962). Das Paleozän und seine Foraminiferenfauna im Becken von Reichenhall und Salzburg. Abhandlungen Bayerischen Akademie der Wissenschaften. Mathematisch-Naturwissenschaftliche Klasse, Neue Folge 108: 1-182. Abhandlungen Bayerischen Akademie der Wissenschaften. 108: 1-182. gs

Leckie, R. M., et al. (2018). 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. 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

Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. 1-252. Smithsonian Institution Press, Washington, DC. (85): 1-252. gs

Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (2006a). Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Globigerina, Globoturborotalita, Subbotina, and Turborotalita. In, Pearson, P. N. , Olsson, R. K. , Hemleben, C. , Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 6): 111-168. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 41(Chap 6): 111-168. gs O

Olsson, R. K., Pearson, P. N. & Huber, B. T. (2006c). Olsson, R. K., Pearson, P. N. & Huber, B. T. (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Catapsydrax, Globorotaloides, Guembelitrioides, Paragloborotalia, Parasubbotina, and Pseudoglobigerinella n. gen. In, Pearson, P. N. , Olsson, R. K. , Hemleben, C. , Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 5): 67-110. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 41(Chap 5): 67-110. gs O

Stainforth, R. M. & Lamb, J. L. (1981). Stainforth, R. M. & Lamb, J. L. (1981). An evaluation of planktonic foraminiferal zonation of the Oligocene. University of Kansas Paleontological Contributions, Papers. 104: 1-34. University of Kansas Paleontological Contributions, Papers. 104: 1-34. gs

Subbotina, N. N. (1953). Subbotina, N. N. (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres. 2239: 1-144. Bureau de Recherches Geologiques et Minieres. 2239: 1-144. gs

test outline:	Subquadrate	chamber arrangement:	Trochospiral	edge view:	Planoconvex	aperture:	Umbilical-extraumbilical
sp chamber shape:	Globular	coiling axis:	Very low	periphery:	N/A	aperture border:	Thin lip
umb chbr shape:	Globular	umbilicus:	Narrow	periph margin shape:	Broadly rounded	accessory apertures:	None
spiral sutures:	Moderately depressed	umb depth:	Deep	wall texture:	Cancellate	shell porosity:	Finely Perforate: 1-2.5µm
umbilical or test sutures:	Strongly depressed	final-whorl chambers:	4-4	N.B. These characters are used for advanced search. N/A - not applicable

Parasubbotina varianta

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

References:

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