pforams@mikrotax - Globigerinatheka subconglobata

Citation: Globigerinatheka subconglobata (Shutskaya 1958)

Basionym: Globigerinoides subconglobatus subconglobata

Synonyms:

Globigerapsis index (Finlay).—Bolli, 1957:165, pl. 36: figs. 14a-b [middle Eocene Globigerapsis kugleri Zone, Navet Fm., Trinidad]. [Not Finlay, 1939.]
Globigerinatheka index index (Finlay).—Bolli, 1972: pl. 1: figs. 6-7 [middle Eocene Globigerinatheka subconglobata subconglobata Zone, Possagno Section, Italy]. [Not Finlay, 1939.]
Globigerinatheka index (Finlay).—Stainforth and others, 1975, figs. 56-5,7,9 (from Bolli, 1972: pl. 1: figs. 2,6,7). [Not Finlay, 1939.]
Globigerinoides subconglobatus Shutskaya var. subconglobatus Shutskaya, 1958:86, pl. I: figs. 4-11 (no designated holotype; lectotype designated by Blow, 1979:819, as the specimen in fig. 8) [upper Eocene, Kerestinskiy horizon, figs. 4, 6-8, 11, Belaya River, Nal’chik region; figs. 5, 9, 10, Nagutskaya well, Mineralovodsk region, Caucasus].
Globigerapsis subconglobatus (Shutskaya).—Toumarkine, 1971: pl. 3: figs. 13-14 [middle Eocene Globorotalia lehneri /Hantkenina dumblei Zone, Halimba borehole, Bakony, Hungary].
Globigerinatheka subconglobata subconglobata (Shutskaya).—Bolli, 1972:134, text-figs. 43-46 (text-fig. 44 lectotype = pl. 1: fig. 8 of Shutskaya, 1958), pl. 1: figs. 8-10, figs. 15-16 [middle Eocene Globigerinatheka subconglobata subconglobata Zone, Possagno Section, northern Italy].—Toumarkine, 1975: pl. 4: fig. 1 [middle Eocene Globorotalia lehneri Zone, DSDP Site 313, Mid Pacific Mountains].—Toumarkine, 1978: pl. 3: figs. 1,3 [middle Eocene Globorotalia lehneri to Truncorotaloides rohri Zone, DSDP Site 360, South Atlantic Ocean]; fig. 2 [middle Eocene Hantkenina aragonensis to Globorotalia lehneri Zone, DSDP Site 363, South Atlantic Ocean].— Toumarkine, 1983: pl. 21 (partim): figs. 17-20 [middle Eocene Globigerinatheka subconglobata subconglobata Zone, Possagno Section, northern Italy]; figs. 18-20 [middle Eocene, Possagno Section, Italy] (not fig. 16 [middle Eocene, Beni Mazar, Boukhary Section, Nile Valley, Egypt] = G. kugleri).
?Globigerinatheka subconglobata subconglobata (Shutskaya).—Fleisher, 1974: pl. 8: fig. 9 [middle Eocene Zone P11, DSDP Site 220, Arabian Sea].
Globigerinatheka subconglobata (Shutskaya).—Stainforth and others, 1975, figs. 90. 1-5 (from Bolli, 1972); figs. 90.6-11 (from Shutskaya, 1958).—Pujol, 1983: pl. 5: figs. 8-9 [middle Eocene Zones P11-13, DSDP Hole 516F, Rio Grande Rise, South Atlantic Ocean].—Pearson and others, 1993: pl. 2: figs. 16-17 [middle Eocene, DSDP Site 523, South Atlantic Ocean].—Poag and Commeau, 1995: pl. 4: figs. 18-19 [middle Eocene Zone P11, Hammond core, 1,320-1,330 ft, SW Salisbury Embayment, Virginia-Maryland].
?Globigerinatheka subconglobata (Shutskaya).—Snyder and Waters, 1985: pl. 5: figs. 5-6 [fig. 5, DSDP Site 549; fig. 6, DSDP Hole 548A, Goban Spur, eastern North Atlantic Ocean].
Globigerinatheka mexicana mexicana (Cushman).— Toumarkine, 1978: pl. 4: fig. 5 [middle Eocene Hantkenina aragonensis to Globorotalia lehneri Zone, DSDP Site 363, South Atlantic Ocean].—Toumarkine, 1983: pl. 20: ?figs. 36-38 [middle Eocene Zones P12-14, DSDP Site 305, Shatsky Rise, northwest Pacific Ocean]. [Not Cushman, 1925.]
Not Globigerinatheka subconglobata subconglobata (Shutskaya).—Toumarkine, 1975: pl. 4: fig. 2 [middle Eocene Globorotalia lehneri Zone, DSDP Site 313, Mid Pacific Mountains] (= G. korotkovi).

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]

Distinguishing features:
Parent taxon (Globigerinatheka): Medium to large, subspherical to spherical tests; multiple secondary apertures, frequently covered by bullae.
This taxon: 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.

Description

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]

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]

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

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]

Biogeography and Palaeobiology

Cosmopolitan, common. [Premoli Silva et al. 2006]

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

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]

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

Primary source for this page: Premoli Silva et al. 2006 - Eocene Atlas, chap. 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. 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

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

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 O

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. gs

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. gs

Premoli Silva, I., Wade, B. S. & Pearson, P. N. (2006). Taxonomy, biostratigraphy, and phylogeny of Globigerinatheka and Orbulinoides. 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 7): 169-212. gs O

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. gs

Shutskaya, E. K. (1958). Variability in some lower Paleogene planktonic foraminifera from the northern Caucasus. Voprosyi Mikropaleontologii. 2: 86-90. gs

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. 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, Articles. 62: 1-425. gs O

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. gs

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. gs

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. gs

Toumarkine, M. (1983). Les Foraminifères planctoniques de l’Eocène moyen et supérieur des régions tropicales à temperées chaudes. In, p1-219 (ed.) . PhD thesis, Université Pierre et Marie Curie, Paris 6 1-219. gs

test outline:	Circular	chamber arrangement:	Trochospiral	edge view:	Equally biconvex	aperture:	Umbilical
sp chamber shape:	Globular	coiling axis:	Low	periphery:	N/A	aperture border:	N/A
umb chbr shape:	Globular	umbilicus:	Narrow	periph margin shape:	Broadly rounded	accessory apertures:	Sutural
spiral sutures:	Moderately depressed	umb depth:	Deep	wall texture:	Spinose	shell porosity:	Finely Perforate: 1-2.5µm
umbilical or test sutures:	Moderately depressed	final-whorl chambers:	4-4	N.B. These characters are used for advanced search. N/A - not applicable

Globigerinatheka subconglobata

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

References:

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