Helvetoglobotruncana microhelvetica

Classification: pf_mesozoic -> Hedbergellidae -> Helvetoglobotruncana -> Helvetoglobotruncana microhelvetica
Sister taxa: H. helvetica, H. microhelvetica, H. praehelvetica, H. sp.


Citation: Helvetoglobotruncana microhelvetica Huber & Petrizzo, in Huber et al. 2017
Rank: Species
Basionym: Helvetoglobotruncana microhelvetica Huber & Petrizzo
Type species: Helvetoglobotruncana microhelvetica Huber & Petrizzo

Type images:

Original 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:Subcircularchamber arrangement:Trochospiraledge view:Planoconvexaperture:-
sp chamber shape:Petaloidcoiling axis:Moderateperiphery:Single keelaperture border:Thick lip
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Moderately roundedaccessory apertures:None
spiral sutures:Raised beadedumb depth:Deepwall texture:-shell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-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. gs


Helvetoglobotruncana microhelvetica compiled by the pforams@mikrotax project team viewed: 23-1-2021

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Short stable page link: http://mikrotax.org/pforams/index.php?id=110276 Go to Archive.is to create a permanent copy of this page - citation notes

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