pforams@mikrotax - Globuligerina balakhmatovae pforams@mikrotax - Globuligerina balakhmatovae

Globuligerina balakhmatovae


Classification: pf_mesozoic -> Conoglobigerinidae -> Globuligerina -> Globuligerina balakhmatovae
Sister taxa: G. avariformis, G. balakhmatovae, G. bathoniana, G. dagestanica, G. glinskikhae, G. jurassica, G. oxfordiana, G. tojeiraensis, G. waskowskae, G. sp.

Taxonomy

Citation: Globuligerina balakhmatovae (Morozova in Morozova & Moskalenko, 1961)
taxonomic rank: Species
Basionym: Globigerina (Eoglobigerina) balakhmatovae Morozova in Morozova & Moskalenko, 1961
Synonyms:
Taxonomic discussion: Recombination in Globuligerina follows Gradstein et al. 2017

Type images:

Original description: DiagnosisEoglobigerlna with a low spiral, consisting of two whorls. The first whorl comprises 3 to 5½ chambers and the final whorl contains 4 chambers. Wall thin, porous.
Description - Test small, low, its height approximately one-half the diameter. Spiral, formed by two whorls. The final whorl is two or three times higher than the first and consists of 4 rapidly increasing chambers which are slightly compressed along their height. The first whorl consists of 3 to 5½  chambers. Sutures between chambers weakly depressed, straight; those between the chambers of the first whorl sometimes slightly oblique. Aperture single, small, rounded, rimmed by a. narrow, weakly expressed lip. Wall thin, radiate, finely porous. Surface smooth, shiny or matte.

Entries in the Catalog of original descriptions: Globigerina (Eoglobigerina) balakhmatovae


Emended description:

Test small, less than 150 µm. Low spiral test, consisting of two whorls, the first small one with 4, rarely 3-5 chambers and the final, much larger and wider one with 4 chambers; H/D ratio about 0.5. Chambers mostly globular, rounded, but in the last whorl may become slightly compressed along their height (flattened), giving an ovate chamber shape. Last whorl chambers wide in an equatorial sense, petaloid and resembling a ‘flower’. Umbilicus slightly open. Sutures between the chambers weakly depressed, straight in the last whorl. Specimens have no bulla. In Grand Banks and Portugese samples rare specimens occur with an imperforate peripheral band; aperture small, a half circle arch or low arch, with narrow rim; wall surface shiny or matte, smooth to finely pustulose in Middle Jurassic strata and may become coarse pustulose with fused ridges in Kimmeridgian sediments.

Character matrix
test outline:Lobatechamber arrangement:Trochospiraledge view:Spiroconvexaperture:Umbilical
sp chamber shape:Globularcoiling axis:Lowperiphery:N/Aaperture border:N/A
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Weakly depressedumb depth:Shallowwall texture:Finely pustuloseshell porosity:Microperforate: <1µm
umbilical or test sutures:Weakly depressedfinal-whorl chambers:4-4 N.B. These characters are used for advanced search. N/A - not applicable

Geological Range:
Last occurrence (top): within Early Kimmeridgian Substage (152.20-154.78Ma, top in Kimmeridgian stage). Data source: Gradstein et al. 2017
First occurrence (base): within Late Bajocian Substage (168.17-169.70Ma, base in Bajocian stage). Data source: Gradstein et al. 2017

Plot of range and occurrence data:

References:

Gradstein, F. & Waskowska, A. (2021). New insights into the taxonomy and evolution of Jurassic planktonic foraminifera. Swiss Journal of Palaeontology. 140(1): 1-12. gs O

Gradstein, F. M., Gale, A. S., Kopaevich, L., Waskowska, A., Grigelis, A. & Glinskikh, L. (2017b). The planktonic foraminifera of the Jurassic. Part I: material and taxonomy. Swiss Journal of Palaeontology. 136(2): 187-257. gs O

Kendall, S., Gradstein, F., Jones, C., Lord, O. T. & Schmidt, D. N. (2020). Ontogenetic disparity in early planktic foraminifers. Journal of Micropalaeontology. 39: 27-39. gs O

Morozova, V. G. & Moskalenko, T. A. (1961). Планктонные фораминиферы пограничных отложений байосского и батского ярусов Центрального Дагестана (Северо-Восточный Кавказ) [Foraminiferes planctoniques des depots limitrophes du Bajocien et du Bathonien du Daghestan central (Nord-Est du Caucase)]. Voprosyi Mikropaleontologii. 5: 3-30. gs

Simmons, M. D., Boudagher-Fadel, M. K., Banner, F. T. & Whittaker, J. E. (1997). The Jurassic Favusellacea, the earliest Globigerina. In, Boudagher-Fadel, M. K., Banner, F. T. & Whittaker, J. E. (eds) The Early Evolutionary History of Planktonic Foraminifera. British Micropalaeontological Society Publication Series . 17-30. gs


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Globuligerina balakhmatovae compiled by the pforams@mikrotax project team viewed: 20-9-2024

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