Huber et al 2017 pl5-05.JPG
Huber et al 2017 pl5-04.JPG
Huber et al 2017 pl5-06.JPG
Huber et al 2017 pl5-05.JPG
Huber et al 2017 pl5-04.JPG
Huber et al 2017 pl5-06.JPGTaxonomy
holotype: H. microhelvetica
paratype: H. microhelvetica
paratype: H. microhelveticaOriginal description: Test small, inequally biconvex, with a maximum diameter of 200–270 μm and maximum breadth 100 to 130 μm, normal perforate (pore size 1.2 to 2.4 μm), nearly planoconvex, subcircular in equatorial outline; equatorial periphery weakly lobate; peripheral margin imperforate except final chamber, which may or may not be perforate; 12–14 chambers in adult tests increase gradually in size as added, with 5–6 in the final whorl; umbilical chambers inflated, chamber surfaces with randomly scattered, fine to moderate-sized pustules, umblical sutures radial and depressed; spiral chambers petaloid, chamber surfaces slightly inflated, with slight convexity toward the peripheral margin, weakly pustulose to smooth with weak alignment of pustules along the peripheral chamber margin, spiral sutures initially depressed and radial, later with weakly aligned pustules; in edge view final chamber offset with respect to spiral coil surface and final chamber face is slightly concave and angled backwards from the peripheral margin; aperture a circular arch that is mostly extra-umbilical in position and bordered by a narrow lip.
Entries in the Catalog of original descriptions: Helvetoglobotruncana microhelvetica
Size: Maximum test diameter: holotype 212 μm,illustrated paratype and hypotypes 209 to 264 μm;maximum breadth: holotype 125 μm, illustrated paratype and hypotypes 97 to 128 μm.
Geological Range:
Last occurrence (top): near top of helvetoglobotruncana helvetica zone (90% up, 92.7Ma, in Turonian stage). Data source: Huber et al., 2017
First occurrence (base): near base of Helvetoglobotruncana helvetica zone (10% up, 93.4Ma, in Turonian stage). Data source: Huber et al., 2017
Plot of range and occurrence data:
Character matrix
| test outline: | Subcircular | chamber arrangement: | Trochospiral | edge view: | Planoconvex | aperture: | - |
| sp chamber shape: | Petaloid | coiling axis: | Moderate | periphery: | Single keel | aperture border: | Thick lip |
| umb chbr shape: | Globular | umbilicus: | Narrow | periph margin shape: | Moderately rounded | accessory apertures: | None |
| spiral sutures: | Raised beaded | umb depth: | Deep | wall texture: | - | shell porosity: | Finely Perforate: 1-2.5µm |
| umbilical or test sutures: | Moderately depressed | final-whorl chambers: | 5.0-6.0 | N.B. These characters are used for advanced search. N/A - not applicable | |||
Huber, B. T., Petrizzo, M. R., Watkins, D. K., Haynes, S. J. & MacLeod, K. G. (2017a). Correlation of Turonian continental margin and deep-sea sequences in the subtropical Indian Ocean sediments by integrated planktonic foraminiferal and calcareous nannofossil biostratigraphy. Newsletters on Stratigraphy. 50: 141-185. gsReferences:
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Helvetoglobotruncana microhelvetica compiled by the pforams@mikrotax project team viewed: 23-1-2021
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