Globigerinatheka korotkovi


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

Taxonomy

Citation: Globigerinatheka korotkovi (Keller 1946)
Rank: Species
Basionym: Globigerinoides korotkovi
Synonyms:
Variants: ko
Taxonomic discussion: Keller (1946), in the original discussion, stated that “the present species differs from the Paleogene Globigerinoides conglobatus Brady from the upper Eocene of the Sotchi region in its much smaller dimensions (0.35-0.37 mm for the Cretaceous form and 0.5-0.6 mm for the Paleogene) and in the single type of structure shown by the representatives of this species”. Keller (1946) also emphasized that his species korotkovi is represented only as “regularly constructed forms” contrary to the high morphological variations observed in what he called the Paleogene Globigerinoides conglobatus.
Subbotina (1953) reillustrated Keller’s specimen and provided the original description, and Bolli (1972) refigured Subbotina’s drawings. Both authors, however, did not mention whether they had found G. korotkovi, nor did they discuss the validity of Keller’s species. On the other hand, Bolli (1972) regarded G. korotkovi as a subspecies of G. index. Following Subbotina (1953), and partially Bolli (1972), later authors ignored korotkovi and attributed common, high-spired globigerinathekid specimens to the species Globigerinoides rubriformis erected by Subbotina in 1953. However, the illustrations of rubriformis, including the holotype (see Subbotina, 1953, pl. 14: figs. 6-9) do not show supplementary apertures. The exception is the specimen figured on Subbotina’s pl. 13, 19a-b, which is here included in G. tropicalis, but the species needs further study to determine its taxonomic validity.
The middle to early late Eocene globigerinathekid population contains common morphotypes that exhibit a sac-like test with a medium-long spire and one subcircular supplementary aperture almost identical to the primary one. So, despite Keller’s poor description, we think that these sac-like, high-spired morphologies are best represented by Keller’s species korotkovi. Keller’s species shows some similarities in general shape with the paratype of G. index illustrated by Finlay in his fig. 87, but redrawing of the latter by Hornibrook (1958) shows well incised sutures lacking in G. korotkovi.
Blow (1979) considered G. korotkovi as taxonomically indistinguishable from G. semiinvoluta (= Porticulasphaera semiinvoluta, Blow, 1979, p. 788), an attribution here rejected. In addition, Blow (1979) considered most of Subbotina’s specimens of G. rubriformis, including the holotype, as immature specimens of Porticulapshaera semiinvoluta (p. 813), which we also reject here. The specimen in Blow, 1979, pl. 181, fig. 3 annotated as a typical G. kugleri, as well as the specimen in Blow, 1979, pl. 174, fig. 3 considered as atypical G. index, seem close to G. korotkovi for their prominent high spire and high subcircular primary aperture, respectively. [Premoli Silva et al. 2006]

Catalog entries: Globigerinoides korotkovi;

Type images:

Short diagnosis: This morphotype is characterized by a high trochospire with three chambers in the last whorl, a rather compact peripheral outline and subcircular primary and supplementary apertures. Based on the presence of at least one supplementary aperture, the species korotkovi is included here in the genus Globigerinatheka. Globigerinatheka korotkovi differs from Subbotina’s species rubriformis in having a much shorter (not turreted) spire and at least one subcircular supplementary aperture; it differs from G. subconglobata in having a last chamber that is much larger, and subcircular openings much smaller than G. index.

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: This morphotype is characterized by a high trochospire with three chambers in the last whorl, a rather compact peripheral outline and subcircular primary and supplementary apertures. Based on the presence of at least one supplementary aperture, the species korotkovi is included here in the genus Globigerinatheka. Globigerinatheka korotkovi differs from Subbotina’s species rubriformis in having a much shorter (not turreted) spire and at least one subcircular supplementary aperture; it differs from G. subconglobata in having a last chamber that is much larger, and subcircular openings much smaller than G. index. [Premoli Silva et al. 2006]

Wall type: Spinose, cancellate, moderately incrusted with pores about 4 mm in diameter. [Premoli Silva et al. 2006]

Test morphology: Test shape sack-like consisting of 2 to 3 whorls arranged in a high trochospire; chambers subglobular with three chambers in the last whorl; sutures distinct, depressed, straight to slightly curved; peripheral outline rather compact; primary aperture a medium-sized subcircular arch at the junction of the sutures of the last three chambers with one subcircular secondary aperture almost identical to the primary one; other much smaller secondary apertures may be present on the spiral side of the previous chambers. [Premoli Silva et al. 2006]

Size: Dimensions of the holotype: diameter 0.35 mm; thickness 0.58 mm. [Premoli Silva et al. 2006]

Character matrix

test outline:Subcircularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:Interiomarginal
umb chamber shape:Globularcoiling axis:Highperiphery:N/Aaperture border:N/A
sp chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:Sutural
umbilical or test sutures:Strongly depressedumb depth:Deepwall texture:Spinoseshell porosity:Macroperforate: >2.5µm
spiral sutures:Strongly depresseddiameter mm:0.35width mm:breadth mm:0.58
final-whorl chambers:3.0-3.0

Biogeography and Palaeobiology


Geographic distribution: Described from the Caucasus, it is commonly found in low and middle latitudes from deep-sea and land sections. [Premoli Silva et al. 2006]

Isotope paleobiology: No data available. [Premoli Silva et al. 2006]

Phylogenetic relations: Bolli (1972) suggested that G. rubriformis (here G. korotkovi) may be regarded as a high-spired variant of G. index and G. tropicalis, a hypothesis not accepted here as we consider G. korotkovi to be a valid taxon which probably descended from G. subconglobata. [Premoli Silva et al. 2006]

Biostratigraphic distribution

Geological Range:
Notes: Globigerinatheka korotkovi was originally reported from lower Senonian strata. In agreement with Bolli (1972), the age is not correct. According to the present study, high-spired morphotypes consistent with G. korotkovi range from lower E9 to lower E15 in the upper Eocene. [Premoli Silva et al. 2006]
Last occurrence (top): within E15 zone (34.68-35.89Ma, top in Priabonian stage). Data source: Eocene Atlas
First occurrence (base): within E9 zone (43.23-43.85Ma, base in Lutetian stage). Data source: Eocene Atlas

Plot of occurrence data:

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

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, 120. Ocean Drilling Program, College Station, Texas, 551-568 pp.

Blow, W.H. & Banner, F.T., (1962). The mid-Tertiary (Upper Eocene to Aquitanian) Globigerinaceae. In: Eames, F.E. et al. (Editors), Fundamentals of mid-Tertiary Stratigraphical Correlation. Cambridge University Press, Cambridge, pp. 61-151.

Blow, W.H., (1969). Late middle Eocene to Recent planktonic foraminiferal biostratigraphy. In: Bronnimann, P. and Renz, H.H. (Editors), Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967, Leiden, Netherlands, pp. 380-381.

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

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.

Collection 2831 [sorry, not in our bibliography yet]

description & Bolli 1972 [sorry, not in our bibliography yet]

Finlay 1945 [sorry, not in our bibliography yet]

Hornibrook, N.d.B., (1958). New Zealand Upper Cretaceous and Tertiary foraminiferal zones and some overseas correlations. Micropaleontology, 4: 25-38.

Keller, B.M., (1946). Foraminifera of the Late Cretaceous deposits of the Sochi region. Biulletin Moskovskogo Obshchestvo Ispytateley Prirody, otd. Geologiy, 21: 83-108.

Loeblich, A.R. & Tappan, H., (1957). Woodringina, a new foraminiferal genus (Heterohelicidae) from the Paleocene of Alabama. Journal of the Washington Academy of Sciences., 47: 39-40.

Loeblich, A.R., Jr. & Tappan, H., (1957). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. 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. 173-198.

Nocchi, M.; Amici, E. & Premoli Silva, I., (1991). Planktonic foraminiferal biostratigraphy and paleoenvironmental interpretation of Paleogene faunas from the subantarctic transect, Leg 114. In: Ciesielski, P.F., Kristoffersen, Y. and al., e. (Editors), Proceedings of the Ocean Drilling Program, Scientific Results. Ocean Drilling Program, College Station, Texas, pp. 233-273.

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.

Samuel, O. & Salaj, J., (1968). Microbiostratigraphy and Foraminifera of the Slovak Carpathian Paleogene. Geologicky Ustav Dionyza Stura, Bratislava: 1-232.

Silva & Spezzaferri 1990 [sorry, not in our bibliography yet]

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., (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 korotkovi compiled by the pforams@mikrotax project team viewed: 19-10-2017

Taxon Search:
Advanced Search
AphiaID: 1035037 Nomenclatural data on WoRMS
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