Globigerinatheka subconglobata


Classification: pf_cenozoic -> spinose -> Globigerinidae -> Globigerinatheka -> Globigerinatheka subconglobata
Sister taxa: G. semiinvoluta, G. tropicalis, G. luterbacheri, G. euganea, G. index, G. curryi, G. barri, G. korotkovi, G. kugleri, G. mexicana, G. subconglobata, G. sp.,

Taxonomy

Citation: Globigerinatheka subconglobata Shutskaya 1958
Rank: Species
Basionym: Globigerinoides subconglobatus subconglobata
Synonyms:
Variants: sb
Taxonomic discussion: Shutskaya (1958) first described and illustrated this taxon as Globigerinoides subconglobatus even though she indicated Khalilov as its author in referring to a manuscript never published; because of Khalilov’s manuscript, Shutskaya did not indicate the holotype; Bolli (1972) selected as a lectotype the specimen that Shutskaya (1958) illustrated in her pl. 1, fig. 8. Globigerinatheka subconglobata (including the smallest specimens) is the only globigerinathekid possessing four visible chambers in the last whorl. Because the original figures of G. subconglobata lack spiral and side views, most authors illustrated this species only in umbilical view, until this atlas. Judging from the figures, the specimen illustrated by Bolli (1957) as G. index (pl. 36, figs. 14a-b) appears to be one of the best representatives of G. subconglobata.
Bolli (1972) considered G. curryi as a subspecies of G. subconglobata; however, in our opinion these species have little in common. Globigerinatheka subconglobata is characterized by a longer and much higher spire, more numerous chambers (four in the last whorl), a small flattened final chamber not enveloping or covering previous ones. Blow (1979, p. 819) suggested that G. subconglobata was a junior synonym of G. kugleri, a synonymy here rejected on the basis of the very different outline and coiling mode (see above). The specimen illustrated by Toumarkine (1983) as Globigerinatheka subconglobata subconglobata (pl. 21, fig. 16) possesses a subtriangular outline similar to G. kugleri. [Premoli Silva et al. 2006]

Catalog entries: Globigerinoides subconglobatus subconglobata;

Type images:

Short diagnosis: Test evolute, 4 chambers in final whorl, with crown-like flatter final chamber. Apertures small. Initial spire in central position. Test size highly variable. In smaller morphotypes, secondary apertures are small or even poorly visible. Wall frequently recrystallized.

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.

Description


Diagnostic characters: Globigerinatheka subconglobata is characterized by its evolute outline, four chambers in the last whorl, crown-like flatter final chamber, small apertures and initial spire which is central in position. Globigerinatheka subconglobata shows some variability in the size and shape of the primary and secondary apertures, whereas the general size of the test is highly variable (see above). In smaller morphotypes, secondary apertures are small or even poorly visible. The wall of G. subconglobata is frequently recrystallized. [Premoli Silva et al. 2006]

Wall type: Spinose, cancellate, rather thick, with pores about 4 µm in diameter, frequently recrystallized. [Premoli Silva et al. 2006]

Test morphology: Test globular to nearly spherical, formed by 3 whorls, initially coiled in low trochospire becoming progressively higher and slightly streptospiral in the last whorl; chambers globular, small and very slowly increasing in size as added up to half of the second whorl, then increasing gradually but progressively faster; the first chamber of the last whorl is about half the size of the antepenultimate, the latter and penultimate chamber have a very similar size, the last chamber is typically smaller and flattened; initially 4 to 5 chambers per whorl, and typically 4 chambers in the last whorl; in spiral view chambers of the last whorl longer than wide, elongate in coiling direction, in umbilical view the last chamber is small and straddles the three previous chambers; sutures distinct throughout, weakly depressed in the inner coils, then moderately depressed; primary aperture umbilical, a low rather wide arch at the base of the last chamber, one to two small low arched secondary apertures at the intersections between the base of the last chamber and previous sutures, apertures frequently poorly visible. [Premoli Silva et al. 2006]

Size: The size of specimens is highly variable ranging in diameter from 0.30 mm to 0.65 mm; medium sized specimens are rather common. Diameter of the lectotype (Shutskaya, 1958, pl. 1, fig. 8) ca. 0.50 mm. [Premoli Silva et al. 2006]

Character matrix

test outline:Circularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
umb chamber shape:Globularcoiling axis:Lowperiphery:N/Aaperture border:N/A
sp chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:Sutural
umbilical or test sutures:Moderately depressedumb depth:Deepwall texture:Spinoseshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Moderately depresseddiameter mm:0.5width mm:breadth mm:
final-whorl chambers:4.0-4.0

Biogeography and Palaeobiology


Geographic distribution: Cosmopolitan, common. [Premoli Silva et al. 2006]

Isotope paleobiology: Recorded as a surface mixed-layer dweller by Pearson and others (1993). [Premoli Silva et al. 2006]

Phylogenetic relations: Globigerinatheka subconglobata is the earliest globigerinathekid and evolved in the early middle Eocene Zone E8, probably from Guembelitrioides nuttalli. It is considered ancestral to all the other globigerinathekid lineages or groups. [Premoli Silva et al. 2006]

Most likely ancestor: Guembelitrioides nuttalli - at confidence level 3 (out of 5). Data source: Premoli Silva et al. 2006 f7.1.

Biostratigraphic distribution

Geological Range:
Notes: The oldest positively identified small specimens of G. subconglobata are recorded in the upper lower part of Zone E8 (= P10); typical larger specimens are recorded slightly higher in mid Zone E8 and range into Zone E13. [Premoli Silva et al. 2006]
The LAD of Globigerinatheka semiinvoluta marks the base of zone E15 / top of E14 (Wade et al. 2011)
Last occurrence (top): within E13 zone (37.99-39.97Ma, top in Bartonian stage). Data source: Premoli Silva et al. 2006 f7.1
First occurrence (base): within E8 zone (43.85-45.72Ma, base in Lutetian stage). Data source: Premoli Silva et al. 2006 f7.1

Plot of occurrence data:

Primary source for this page: Premoli Silva et al. 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 7

References:

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, 1413 pp.

Bolli, H.M., (1957). The foraminiferal genus Schackoina Thalmann, emended, and Leupoldina, n. gen. in the Cretaceous of Trinidad, B. W. I. Eclogae Geologicae Helvetiae, 50(2): 271-278.

Bolli, H.M., (1957). The genera Globigerina and Globorotalia in the Paleocene-Lower Eocene Lizard Springs Formation of Trinidad. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 61-82.

Bolli, H.M., (1957). Planktonic foraminifera from the Eocene Navet and San Fernando formations of Trinidad. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera: U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 155-172.

Bolli, H.M., (1957). Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera: U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, DC, pp. 97-123.

Bolli, H.M., (1957). The genera Praeglobotruncana, Rotalipora, Globotruncana, and Abathomphalus in the Upper Cretaceous of Trinidad, B. W. I. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 51-60.

Bolli, H.M., (1972). Correlation de las estaciones JOIDES 29, 30 y 31 del Caribe con Jamaica, Venezuela y Trinidad. Memoria IV Congreso Geologico Venezolano, 3, 1315-1336 pp.

Bolli, H.M., (1972). The genus Globigerinatheka Bronnimann. Journal of Foraminiferal Research, 2(3): 109-136.

Cushman, J.A., (1925). An Eocene fauna from the Moctezuma River, Mexico. Bulletin of the American Association of Petroleum Geologists, 9(2): 298-301.

Cushman, J.A., (1925). New foraminifera from the Upper Eocene of Mexico. Contributions from the Cushman Laboratory for Foraminiferal Research, 1(1): 4-9.

Cushman, J.A., (1925). Some new foraminifera from the Velasco shale of Mexico. Contributions from the Cushman Laboratory for Foraminiferal Research, 1(6): 18-23.

Cushman, J.A., (1925). A new genus of Eocene foraminifera. Proceedings of the United States National Museum, 66.

Finlay, H.J., (1939). New Zealand foraminifera: Key species in stratigraphy - no. 1. Transactions of the Royal Society of New Zealand, 68: 504-533.

Finlay, H.J., (1939). New Zealand foraminifera: Key species in stratigraphy - no. 3. Transactions of the Royal Society of New Zealand, 69(3): 309-329.

Finlay, H.J., (1939). New Zealand foraminifera: Key species in stratigraphy - no. 2. Transactions of the Royal Society of New Zealand, 69(1): 89-128.

Fleisher, R.L., (1974). Preliminary report on Late Neogene Red Sea foraminifera, Deep Sea Drilling Project, Leg 23B. Initial Reports of the Deep Sea Drilling Project, 26: 985-1011.

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

Pearson, P.N.; Shackleton, N.J. & Hall, M.A., (1993). Stable isotope paleoecology of middle Eocene planktonic foraminifera and multi-species isotope stratigraphy, DSDP Site 523, South Atlantic. Journal of Foraminiferal Research, 23: 123-140.

Poag, C.W. & Commeau, J.A., (1995). Paleocene to middle Miocene planktic foraminifera of the southwestern Salisbury Embayment, Virginia and Maryland: Biostratigraphy, allostratigraphy, and sequence stratigraphy. Journal of Foraminiferal Research, 25: 134-155.

Premoli Silva, I.; Wade, B.S. & Pearson, P.N., (2006). Taxonomy, biostratigraphy, and phylogeny of Globigerinatheka and Orbulinoides. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Allen Press, Lawrence, Kansas, pp. 169-212.

Pujol, C., (1983). Cenozoic planktonic foraminiferal biostratigraphy of the South-Western Atlantic (Rio Grande Rise): Deep Sea Drilling Project Leg 72. Initial Reports of the Deep Sea Drilling Project, 72: 623-673.

Shutskaya, E.K., (1958). Variability in some lower Paleogene planktonic foraminifera from the northern Caucasus. Voprosy Mikropal, Moscow, 1958(2): 86.

Snyder, S.W. & Waters, V.J., (1985). Cenozoic planktonic foraminiferal biostratigraphy of the Goban Spur Region, Deep Sea Drilling Project Leg 80. Initial Reports of the Deep Sea Drilling Project, 80: 439-472.

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

Toumarkine, M., (1971). Etude des Foraminifères planctoniques de deux sondages (H-S49 et PGYT-31) dans l’ Eocène de la Montagne du Bakony (Transdanubie, Hongrie). Annales Instituti Geologici Publici Hungarici, 54: 283-299.

Toumarkine, M., (1975). Middle and Late Eocene planktonic foraminifera from the northwestern Pacific Ocean: Leg 32 of the Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project, 32: 735-751.

Toumarkine, M., (1978). Planktonic foraminiferal biostratigraphy of the Paleogene of Sites 360 to 364 and the Neogene of Sites 362A, 363 and 364 Leg 40,. Initial Reports of the Deep Sea Drilling Project, 40: 679-721.

Toumarkine, M., (1983). Les Foraminifères planctoniques de l’Eocène moyen et supérieur des régions tropicales à temperées chaudes. PhD Thesis, Université Pierre et Marie Curie, Paris 6, 83-05, 1-219 pp.


logo

Globigerinatheka subconglobata compiled by the pforams@mikrotax project team viewed: 24-11-2017

Taxon Search:
Advanced Search

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