Paragloborotalia birnageae


Classification: pf_cenozoic -> Globigerinidae -> Paragloborotalia -> Paragloborotalia birnageae
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 birnageae (Blow, 1959)
Rank: species
Basionym: Globorotalia birnageae Blow, 1959
Synonyms:
Taxonomic discussion:

Paragloborotalia birnageae and its junior synonyms have previously been attributed to a number of genera, including Globorotalia, Fohsella, and Turborotalita, but is placed here within Paragloborotalia based on its coarsely cancellate wall, and close resemblance with the P. nana-P. pseudokugleri-P. kugleri lineage. As part of our investigations, we have examined the topotypes of P. birnageae housed at the Natural History Museum in London, Blow collection (P49680, P49688); they are very consistent with the holotype, including the extended final chamber.

Globorotalia mendacis (Blow, 1969) is considered to be a junior synonym of P. birnageae. Both taxa have ~6 embracing chambers in the final whorl, a compact test with mostly closed umbilicus and a low aperture with a thin lip, and slightly curved dorsal sutures. Blow (1969) chose a distinctly biconvex specimen with a subacute peripheral margin (Pl. 5.2, Figs. 4-6) for the holotype. However, there is a complete gradation between forms with a broadly rounded margin (P. birnageae s.s.) and specimens that have a subacute margin. Globorotalia mendacis has long been considered a junior synonym of P. kugleri (Stainforth and others, 1975; Bolli and Saunders, 1985). However, our investigations of the holotype reveal that it is synonymous with P. birnageae based on the circular, weakly lobulate equatorial outline, kummerform final chamber with low aperture and flap-like lip. Blow (1979:148) notes that “superficially it [birnageae] bears some general morphological resemblances to G. (T.) kugleri, G. (T.) pseudokugleri and, especially, G. (T.) mendacis”.

Specimens of Paragloborotalia? laccadivensis reported by Spezzaferri (1994) are also likely synonymous with birnageae. The tiny, 5-6 chambered laccadivensis consistently first appears in mid-Oligocene Subzone P21a (= Zone O3/O4; Spezzaferri, 1994). Therefore, these mid-Oligocene to early Miocene forms are probably not the same taxon described by Fleisher (1974) as Globanomalina laccadivensis from the upper Eocene of the Arabian Sea. In her description of the forms she attributed to P.? laccadivensis, Spezzaferri (1994:57) notes: “Sutures are slightly depressed and radial on both sides”. As observed in other lineages of Paragloborotalia, radial spiral sutures are the ancestral condition in all early and mid Oligocene taxa (through Subzone P21a = O3-O4); spiral sutures of birnageae become more curved in the late to latest Oligocene (Zone P22 = O6 and O7).

Turborotalita primitiva was described by Brönnimann and Resig from the upper Oligocene of the southwestern Pacific Ocean and is considered here to be within the morphologic variability of P. birnageae. Although the type specimen is of rather poor quality and equivocal in its identification, it fits best as within the birnagaeae plexus. Moreover, we have re-examined the type level of T. primitiva in DSDP Hole 64A and found specimens attributable to P. birnageae (Pl. 5.3, Fig. 16). [Leckie et al. 2018]

Catalog entries: Globorotalia birnageae, Turborotalita primitiva, Globorotalia (Turborotalia) mendacis

Type images:

Distinguishing features:

5½-7, typically 6,  embracing chambers in the final whorl; last chamber may be kummerform

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:

Paragloborotalia birnageae is distinguished from P. pseudokugleri in having less depressed sutures, a less lobulate test, and a lower aperture. It differs from P. siakensis, P. mayeri, P. semivera, and P. kugleri in being less ovate and more circular in equatorial profile, and in having a nearly closed to closed umbilicus with a distinctive low aperture with lip or apertural flap/flange. The last chamber and aperture may resemble Turborotalita quinqueloba, but P. birnageae has a cancellate wall and a less lobulate equatorial profile (e.g., see Pearson and Wade, 2009). [Leckie et al. 2018]


Wall type: Normal perforate, coarsely cancellate, probably sparsely spinose in life, heavy gametogenetic calcification is often present.

Test morphology: Test small to medium in size; low trochospiral, weakly lobulate in equatorial outline, chambers subglobular, inflated, embracing; 5½-7, typically 6 chambers in the ultimate whorl, increasing slowly in size, ultimate chamber may be smaller than penultimate chamber (kummerform); in spiral view chambers subspherical, arranged in 2½-3 whorls, sutures slightly depressed, nearly radial to curved; in umbilical view chambers subspherical, sutures slightly depressed, radial, umbilicus narrow, moderately deep; may have an ampullate final chamber; aperture a low slit extending midway onto the peripheral edge, typically bordered by a lip or flap-like flange (apertural plate) as in Turborotalita quinqueloba and Neogloboquadrina acostaensis; in edge view chambers spherical, spiral side flat to slightly convex, umbilical side slightly convex, periphery broadly rounded to slightly subacute. [Leckie et al. 2018]

Size: Maximum diameter of holotype 0.22 mm (original measurement); 0.18 mm (remeasured this study): thickness 0.10 mm (this study). [Leckie et al. 2018]

Character matrix

test outline:Subcircularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical-extraumbilical
sp chamber shape:Globularcoiling axis:Lowperiphery:N/Aaperture border:Thin flange
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Moderately roundedaccessory apertures:None
spiral sutures:Weakly depressedumb depth:Shallowwall texture:Cancellateshell porosity:Macroperforate: >2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:5.5-7.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Low to mid-latitudes. [Leckie et al. 2018]

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

Phylogenetic relations: Paragloborotalia birnageae evolved from P. nana in the mid-Oligocene by developing a kummerform final chamber, a less lobulate equatorial periphery, and more than 4 chambers in the final whorl. A reference to intergradation between P. birnageae and Trilobatus trilobus by Gradstein and others (2012:1093) is unfounded. [Leckie et al. 2018]
Kennett & Srinivasan (1983) suggested that it might be related to 

Most likely ancestor: Paragloborotalia nana - at confidence level 3 (out of 5). Data source: Leckie et al. 2018.

Biostratigraphic distribution

Geological Range:
Notes: As defined here, P. birnageae has a much longer stratigraphic range than P. pseudokugleri and P. kugleri, which are more restricted. Paragloborotalia birnageae was previously used as a marker to designate the base of Subzone M4b (late early Miocene; Berggren and others, 1995, Wade et al. 2011), however, multiple authors have reported this taxon in the lower Miocene and upper Oligocene (e.g., Blow, 1979; Chaisson and Leckie, 1993; Spezzaferri, 1994). For example, Blow (1979) reported G. mendacis (= P. birnageae) as low as Zone N2 (= Zone P21). In addition, Spezzaferri (1994) recorded the lowest/oldest confirmed occurrence of P.? laccadivensis (= P. birnageae) in mid-Zone O5 (= Subzone P21b), with more questionable occurrences as low as mid-Zone O4 (=Subzone P21a). These reported occurrences clearly pre-date the lowest occurrence of P. pseudokugleri. [Leckie et al. 2018]
Last occurrence (top): within N8 zone (15.10-16.38Ma, top in Langhian stage). Data source: Kennett & Srinivasan 1983 f12
First occurrence (base): within O5 zone (26.93-28.09Ma, base in Chattian 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.132

References:

Berggren, W. A., Kent, D. V., Swisher, I. , C. C. & Aubry, M. -P. (1995b). A revised Cenozoic geochronology and chronostratigraphy. In, Berggren, W. A. , Kent, D. V. , Aubry, M. -P. & Hardenbol, J. (eds) Geochronology, Time Scales and Global Stratigraphic Correlations. SEPM (Society for Sedimentary Geology) Special Publication No. 54, 129-212. gs

Blow, W. H. (1959). Age, correlation, and biostratigraphy of the upper Tocuyo (San Lorenzo) and Pozon Formations, eastern Falcon, Venezuela. Bulletins of American Paleontology. 39(178): 67-251. gs

Blow, W. H. (1969). Late middle Eocene to Recent planktonic foraminiferal biostratigraphy. In, Bronnimann, P. & Renz, H. H. (eds) Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967. E J Brill, Leiden 380-381. 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. & Saunders, J. B. (1985). Oligocene to Holocene low latitude planktic foraminifera. In, Bolli, H. M. , Saunders, J. B. & Perch-Neilsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge, UK 155-262. gs

Brönnimann, P. & Resig, J. (1971). A Neogene globigerinacean biochronologic time-scale of the southwestern Pacific. Initial Reports of the Deep Sea Drilling Project. 7(2): 1235-1469. gs

Chaisson, W. P. & Leckie, R. M. (1993). High-resolution Neogene planktonic foraminifer biostratigraphy of Site 806, Ontong Java Plateau (Western Equatorial Pacific). Proceedings of the Ocean Drilling Program, Scientific Results. 130: 137-178. gs

Chaproniere, G. C. H. (1981). Late Oligocene to Early Miocene planktic Foraminiferida from Ashmore Reef no. 1 well, northwest Australia. Alcheringa. 5: 103-131. gs

Fleisher, R. L. (1974a). Cenozoic planktonic foraminifera and biostratigraphy, Arabian Sea, Deep Sea Drilling Project, Leg 23A. Initial Reports of the Deep Sea Drilling Project. 23: 1001-1072. gs

Gradstein, F., Ogg, J., Schmitz, M. & Ogg, G. (2012). The Geologic Time Scale 2012. Elsevier, . -. 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

Norris, R. D. (1998). Planktonic foraminifer biostratigraphy: Eastern Equatorial Atlantic. Proceedings of the Ocean Drilling Program, Scientific Results. 159: 445-479. gs

Pearson, P. N. & Wade, B. S. (2009). Taxonomy and stable isotope paleoecology of well-preserved planktonic foraminifera from the uppermost Oligocene of Trinidad. Journal of Foraminiferal Research. 39: 191-217. gs

Poore, R. Z. (1979). Oligocene through quarternary planktonic foraminiferal biostratigraphy of the North Atlantic: DSDP LEG 49. Initial Reports of the Deep Sea Drilling Project. 49: 447-517. gs

Quilty, P. G. (1976). Planktonic foraminifera DSDP Leg 34, Nazca Plate. Initial Reports of the Deep Sea Drilling Project. 34: 629-703. gs

Salvatorini, G. & Cita, M. B. (1979). Miocene foraminiferal stratigraphy, DSDP site 397 (Cape Bojador, North Atlantic). Initial Reports of the Deep Sea Drilling Project. 47/1: 317-373. 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

Stainforth, R. M., Lamb, J. L., Luterbacher, H., Beard, J. H. & Jeffords, R. M. (1975). Cenozoic planktonic foraminiferal zonation and characteristics of index forms. University of Kansas Paleontological Contributions. 62: 1-425. gs

Wade, B. S., Pearson, P. N., Berggren, W. A. & Pälike, H. (2011). Review and revision of Cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale. Earth-Science Reviews. 104: 111-142. gs


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Paragloborotalia birnageae compiled by the pforams@mikrotax project team viewed: 22-10-2019

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Short stable page link: http://mikrotax.org/pforams/index.php?id=104342 Go to Archive.is to create a permanent copy of this page - citation notes



Comments (1)

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SMay

this is a Paragloborotalia now (there is another entry under P. birnageae)

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Jeremy Young (Tonbridge, UK)

Thank you Sarah - I have corrected that now. Please do point out any other mistakes like the - adding the Oligocene content and merging the Neogene and Paleogene databases was a major task and there may be other errors of this type left behind.

Jeremy

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