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Globuligerina balakhmatovae


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

Taxonomy

Citation: Globuligerina balakhmatovae (Morozova in Morozova & Moskalenko, 1961)
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


Diagnostic characters:

This is the only Jurassic species and morphotype with a low spire and globular rounded to ovate chamber shape, a small, rounded aperture, and no bulla. The test surface in stratigraphically older material is smoother than in other Jurassic planktonic foraminiferal taxa. Flattening of the chambers is observed both in the Grand Banks and in the Portugal material. It was also mentioned in the description by Morozova (In Morozova and Moskalenko, 1961) and by Bignot and Guyader (1966) for the Middle Jurassic type specimens in Dagestan. Flattening of the test is not the result of post-mortem compaction.


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.

Geological Range:
Last occurrence (top): within Early Kimmeridgian Substage (154.73-157.25Ma, top in Kimmeridgian stage). Data source: Gradstein et al. 2017
First occurrence (base): within Late Bajocian Substage (168.28-169.45Ma, base in Bajocian stage). Data source: Gradstein et al. 2017

Plot of occurrence data:

Dec 2017 - Plotting of Neptune data has been re-enabled on the Mesozoic pages following revision of the age-models in Neptune. The data is, however, still very sparse for the Early Cretaceous

  • (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Globuligerina

    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:4.0-4.0 N.B. These characters are used for advanced search. N/A - not applicable

    References:

    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 :: ::

    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)]. Voprosy 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 Micropaleontological Society Series. 17-30. gs :: ::


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    Globuligerina balakhmatovae compiled by the pforams@mikrotax project team viewed: 11-7-2020

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    Short stable page link: http://mikrotax.org/pforams/index.php?id=110057 Go to Archive.is to create a permanent copy of this page - citation notes



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