Parasubbotina


Classification: pf_cenozoic -> Globigerinidae -> Parasubbotina
Sister taxa: Beella, Globigerina, Globigerinella, Protentella, Quiltyella, Ciperoella, Globigerinoides, Globigerinoidesella, Globoturborotalita, Orbulina, Praeorbulina, Sphaeroidinella, Sphaeroidinellopsis, Trilobatus, Turborotalita, Dentoglobigerina, Globoquadrina, Catapsydrax, Clavatorella, Paragloborotalia, Protentelloides, Eoglobigerina, Globigerinatheka, Globorotaloides, Guembelitrioides, Orbulinoides, Parasubbotina, Pseudoglobigerinella, Subbotina,
Daughter taxa: species arranged stratigraphically and by lineage (blue => in age window 0-300Ma)
inaequispira & derived species
Test very low trochospiral, globular with strongly inflated chambers; inner whorls partially overlapped by the ultimate whorl. Wall texture Clavigerinella-type (high porosity, reticulated)
Test low trochospiral, 4-4½ chambers in final whorl. Chamber size increases rapidly, and the last 1 or 2 chambers are often radially extended. Aperture small, interiomarginal umbilical-extraumbilical with a broad, flaring lip. Wall texture reticulate (Clavigerinella-type),
Large adult test, quadrate. Chambers globular, embracing. Aperture low-arched, umbilical-extraumbilical, with thin irregular lip.
Test symmetrical, compressed with radially elongate, globular to cylindrical chambers.
Test, lobulate, very low trochospiral, rather openly coiled, 4-4½ chambers in final whorl, which is much larger than inner whorl. Aperture anteriorly directed umbilical-extraumbilical, lacking thick lip
pseudobulloides-varianta group
Test small, compact, very low trochospiral, typically<5 chambers in final whorl.
Test large (0.4-0.7 mm), loosely coiled, with strongly lobulate outline. Any or all of the last 3-4 chambers with inwardly projecting umbilical teeth. Aperture interiomarginal, umbilical-extraumbilical arch; occasional secondary spiral apertures. Wall spinose and distinctly cancellate with large pore pits.
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.
Test medium-sized (>250µm) with 5 chambers in final whorl. Chambers inflated, globular, slightly ovoid; increasing rapidly in size. Aperture interiomarginal, umbilical to extraumbilical, a high rounded arch with a narrow lip. Umbilicus narrow; deep and open to the previous chambers. Wall cancellate spinose, with numerous spine holes
Test small (<225µm), 4½ to 5 chambers in final whorl. Chambers globular, increase rapidly in size. Aperture high arched umbilical-extraumbilical with a thin lip Wall weakly developed cancellate, spinose.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Parasubbotina Olsson, Hemleben, Berggren, and Liu, 1992
Rank: Genus
Type species: Globigerina pseudobulloides Plummer, 1926.
Taxonomic discussion: In the lower Danian, low trochospiral, cancellate-walled, planktonic foraminiferal species are common and were thought to be phylogenetically linked together. Olsson et al. (1992) showed that two groups can be separated on the basis of a spinose or a nonspinose test morphology. In the earliest Danian, Parasubbotina and Eoglobigerina represent the spinose group and Praemurica represents the nonspinose group. [Olsson et al. 1999]

The genus was originally erected by Olsson and others (1992) to encompass two Danian species, P. pseudobulloides and P. varianta, which are united by a low trochospiral test, high arched aperture and cancellate spinose wall texture. Although they are similar in overall test morphology to closely related Praemurica inconstans and similar forms, their spinose wall texture was considered as being of high taxonomic status, such that Parasubbotina was included in the Family Globigerinidae and Praemurica in the Globorotaliidae. Olsson and others (1992) noted that Parasubbotina ranges at least as high as Zone P4, but the topmost occurrence of P. varianta was not firmly established by them. Thus, initial investigations by the Paleogene Working Group indicated that Parasubbotina might be a short-lived genus restricted to the Paleocene, with the bulk of the Cenozoic spinose radiation stemming from Eoglobigerina (Pearson, 1993).
Parasubbotina was reviewed by Olsson and others (1999). In that work, the stratigraphic range of P. varianta was found to extend at least to the lower Eocene. Further investigations reported here shows that varianta-like morphologies extend as high as the middle Eocene (confirming the original suggestion of Subbotina, 1953) and it now appears that this species was the root of a substantial evolutionary radiation. The new observations indicate that Parasubbotina is closely related to Paragloborotalia, with which it shares the spinose wall, generally low-trochospiral coiling mode and high-arched aperture. The latter genus is distinguished, however, by the thick, continuous lip that rims the aperture and in having a generally slower rate of chamber enlargement, a tighter coiling mode, and more embracing chambers, which tends to result in a quadrate-shaped, more compact test as is typical, for example, in Paragloborotalia nana (Bolli). The number of chambers in the ultimate whorl is usually 4.
A prominent feature of the taxonomy presented here is the inclusion of the frequently decribed species Globigerina inaequispira Subbotina in Parasubbotina, rather than in Subbotina where it has often been placed (e.g., Blow, 1979). This assignment has been made after detailed study of type material on the basis of its coiling mode and the fact that P. inaequispira has been observed to intergrade with other parasubbotinids in high productivity assemblages. [Olsson et al. 2006]

Catalog entries: Parasubbotina;

Type images:

Distinguishing features: Very low trochospiral test, chambers increasing rapidly in size; aperture high-arched umbilical-extraumbilical aperture. At most 5 chambers in final whorl.

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: Genus distinguished by very low trochospiral test, chambers increasing rapidly in size in ultimate whorl, and high-arched umbilical-extraumbilical aperture. Number of chambers never exceeds 5 in ultimate whorl. Last two chambers may be offset toward umbilicus (P. variospira) giving test the appearance of a higher spire. [Olsson et al. 1999]

Wall type: Normal perforate, cancellate, spinose. [Olsson et al. 2006]

Test morphology: Test very low trochospiral, globular, lobulate in outline, chambers globular; in spiral view 4-5 globular, somewhat embracing chambers in ultimate whorl, increasing rapidly in size; in umbilical view 4-5 globular, somewhat embracing chambers, umbilicus a small sized opening, enclosed by surrounding chambers, aperture umbilical-extraumbilical.
[Olsson et al. 2006]

Biogeography and Palaeobiology


Phylogenetic relations: Suggested as having evolved from Hedbergella by Olsson et al. (2006) but Koutsoukos (2014) provided detialed evidence for origin of both Parasubbotina and Eoglobigerina from Praemurica nikolasii. This makes the Globigerinidae polyphyletic, for convenient plotting of the graphs the alternative possibility of Parasubbotina evolving from Eoglobigerina is instead indicated here. NB Alternatively P. nikolasii could be transferred to Eoglobigerina. [editor's comment - JRY 2018]   

Similar species: Genus distinguished by low trochospiral test, chambers increasing rapidly in size in ultimate whorl, and high-arched umbilical-extraumbilical aperture with lip of variable thickness, sometimes dentate. Wall cancellate, originally spinose.
[Olsson et al. 2006]

Most likely ancestor: Eoglobigerina - at confidence level 1 (out of 5). Data source: alternative interpretation of data of Koutsoukos (2014) .
Likely descendants: Clavigerinella; Globorotaloides; Guembelitrioides; Paragloborotalia; Pseudoglobigerinella;

Biostratigraphic distribution

Geological Range:
Last occurrence (top): in lower part of Rupelian Stage (31% up, 32.1Ma, in Rupelian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Danian Stage (0% up, 66Ma, in Danian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Olsson et al. 2006 - Eocene Atlas, chap. 5, p. 96

References:

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

Koutsoukos, E., (2014). Phenotypic plasticity, speciation, and phylogeny in Early Danian planktic foraminifera. Journal of Foraminiferal Research, 44: 109-142.

Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Liu, C., (1992). Wall Texture Classification of planktonic foraminifera genera in the Lower Danian. Journal of Foraminiferal Research, 22(3): 195-213.

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

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. et al. (Editors), Atlas of Eocene Planktonic Foraminifera. Cushman Foundation Special Publication. 41 Allen Press, Lawrence, Kansas, pp. 67-110.

Pearson, P.N., (1993). A lineage phylogeny for the Paleogene planktonic foraminifera. Micropaleontology, 39: 193-232.

Plummer, H.J., (1926). Foraminifera of the Midway formation in Texas. University of Texas Bulletin, 2644: 1-206.


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Parasubbotina compiled by the pforams@mikrotax project team viewed: 15-12-2018

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