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Conoglobigerina gulekhensis


Classification: pf_mesozoic -> Conoglobigerinidae -> Conoglobigerina -> Conoglobigerina gulekhensis
Sister taxa: C. avarica, C. balakhmatovae, C. caucasica, C. conica, C. dagestanica, C. gulekhensis, C. jurassica, C. meganomica, C. terquemi, C. sp.,

Taxonomy

Citation: Conoglobigerina gulekhensis (Gorbachik & Poroshina, 1979)
Rank: Species
Basionym: Globuligerina gulekhensis

Type images:

Original description: Globuligerina gulekhensis Gorbachik & Poroshina 1979: Test small, diameter no more than 0.25 mm, high-trochoid; test outline subquadrate, sharply lobate. The coil making up the initial whorls is somewhat off-center relative to the last whorl and sharply demarcated from its surface. Peripheral margin broad, rounded. Test consists of 12-13 chambers, forming 2.5-3 whorls. Chambers of initial whorls spherical or ellipsoidal, closely appressed. In the last whorl there are four subspherical chambers, more freely arranged. Dimensions of chambers in each whorl increase gradually; the chambers of the early whorls differ markedly in size. Septal sutures depressed straight. Umbilicus shallow, narrow. Aperture opens into umbilicus, arcuate, has a barely noticeable lip. Test wall finely perforate, surface appears smooth under a binocular microscope at X 96, when studied with the electron microscope (X 1000 and X 3000) a clearly expressed cancellate structure is visible. The cells are roughly rectangular, divided by broad, high, smoothed-off ridges. Cells reach 2 µm in size. Pores round or oval, located mainly inside the cells, there are single pores on the ridges as well. There are two orders of pores - small, around 0.33 µm in size; and large - up to 1 µm. Small pores predominate.

Entries in the Catalog of original descriptions: Globuligerina gulekhensis;

Geological Range:
Last occurrence (top): within Valanginian Stage (133.88-139.39Ma, top in Valanginian stage). Data source: [copied from Chronos database]
First occurrence (base): at base of C. gulekhensis zone (0% up, 146Ma, in Tithonian stage). Data source: zonal marker (from Timescale Creator)

Plot of occurrence data:

NB Plotting of Neptune data has been disabled on the Mesozoic pages because the dataset is both small and badly affected by a few sites with erroneous age models (our obs Huber, Petrizzo, Young, Nov 2016). The data can still be viewed via the range plottertool - tools menu.

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Spiroconvexaperture:Umbilical
umb chamber shape:Globularcoiling axis:Moderate-highperiphery:N/Aaperture border:Thin lip
sp chbr shape:Globularumbilicus:Wideperiph margin shape:Broadly roundedaccessory apertures:N/A
umbilical or test sutures:Moderately depressedumb depth:Shallowwall texture:Finely pustuloseshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Moderately depresseddiameter mm:0.18width mm:0.14breadth mm:0.13
final-whorl chambers:4.0-4.0

References:

Gorbachik, T.N. & Poroshina, L.A., (1979). Новые планктонные фораминиферы из берриасских отложений Азербайджана [New planktonic foraminifera from the Berriasian of Azerbaijan]. Paleontological Journal, 3: 22-28.


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Conoglobigerina gulekhensis compiled by the pforams@mikrotax project team viewed: 23-11-2017

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