Parasubbotina varianta


Classification: pf_cenozoic -> Globigerinidae -> Parasubbotina -> Parasubbotina varianta
Sister taxa: P. griffinae, P. eoclava, P. hagni, P. prebetica, P. inaequispira, P. pseudowilsoni, P. variospira, P. varianta, P. pseudobulloides, P. aff. pseudobulloides, P. sp.,

Taxonomy

Citation: Parasubbotina varianta (Subbotina 1953)
Rank: Species
Basionym: Globigerina varianta
Synonyms:
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]

Catalog entries: Globigerina varianta, Globorotalia (Turborotalia) quadrilocula

Type images:

Distinguishing features: 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.

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:

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]


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

Test morphology: 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]

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

Character matrix

test outline:Subquadratechamber arrangement:Trochospiraledge view:Planoconvexaperture:Umbilical-extraumbilical
sp chamber shape:Globularcoiling axis:Very lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:Deepwall texture:Cancellateshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Strongly depressedfinal-whorl chambers:4.0-4.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


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

Isotope paleobiology: Parasubbotina varianta has a ∂13C and ∂18O signature similar to that of P. pseudobulloides, Subbotina triloculinoides, and Globanomalina compressa but typically with heavier ∂18O and more negative ∂13C than coexisting Praemurica and Morozovella. The species shows little change in ∂18O or ∂13C over a large size range. [Olsson et al. 1999]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light δ13C and relatively heavy δ18O. Sources cited by Aze et al. 2011 (appendix S3): Olsson et al. (1999); Pearson et al. (2001a).

Phylogenetic relations: 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]

Most likely ancestor: Parasubbotina pseudobulloides - at confidence level 4 (out of 5). Data source: Olsson et al. 1999 f.5.
Likely descendants: Globorotaloides quadrocameratus; Paragloborotalia griffinoides; Parasubbotina inaequispira; Parasubbotina pseudowilsoni; Parasubbotina variospira;

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

Plot of occurrence data:

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

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. gs

Bolli, H. M. (1957a). 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. gs

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. 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

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

Olsson, R. K., Pearson, P. N. & Huber, B. T. (2006c). 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. gs

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

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


logo

Parasubbotina varianta compiled by the pforams@mikrotax project team viewed: 22-10-2019

Taxon Search:
Advanced Search

Short stable page link: http://mikrotax.org/pforams/index.php?id=100234 Go to Archive.is to create a permanent copy of this page - citation notes



Comments (0)

No comments yet. Be the first!

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics