pforams@mikrotax - Helvetoglobotruncana pforams@mikrotax - Helvetoglobotruncana

Helvetoglobotruncana


Classification: pf_mesozoic -> Hedbergellidae -> Helvetoglobotruncana
Sister taxa: Asterohedbergella, Clavihedbergella, Costellagerina, Falsotruncana, Hedbergella, Helvetoglobotruncana, Liuenella, Microhedbergella, Muricohedbergella, Paracostellagerina, Paraticinella, Praeglobotruncana, Pseudoguembelitria, Whiteinella
Daughter taxa (time control age-window is: 0-800Ma)
Helvetoglobotruncana helvetica

Helvetoglobotruncana microhelvetica

Helvetoglobotruncana praehelvetica

Helvetoglobotruncana sp.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Helvetoglobotruncana Reiss 1957
taxonomic rank: Genus
Type species: Globotruncana helvetica Bolli, 1945

Original description: Test flatly trochospiral; chambers globular, slightly to strongly flattened on the dorsal side; keel dorsal, not necessarily peripheral (sub-peripheral keel) at the margin of the flattened part of the chamber-wall with r dorso-septal branches and never dichotomic; keels granular to subspinose; cameral aperture umbilical, extending slightly into a partly interiomarginal position; labial apertures interiomarginal-umbilical-sutural (latter part often reduced through partial fusion of the lips); lips very slightly, if at all arched lengthwise, covering partly the umbilical cavity.

Entries in the Catalog of original descriptions: Helvetoglobotruncana

Distinguishing features:
Parent taxon (Hedbergellidae): Test trochospirally coiled, primary aperture interiomarginal, extraumbilical-umbilical, with prominent apertural lip, apertures of earlier chambers remain visible around the umbilical region; no sutural secondary apertures.
This taxon: Test in low trochospiral coil, planoconvex, spiral side flattened, umbilical side inflated, with narrow to moderately wide central umbilicus of about one-third to one-fourth the test diameter, chambers subtriangular, broad and inflated on the umbilical side, sutures radial and slightly depressed or may be elevated on the spiral side, peripheral margin marked by a row of pustules or a single keel, peripheral outline lobulate; primary aperture umbilical-extraumbilical, bordered by a well-developed flap or porticus, those of successive chambers overlapping in a ring about the umbilicus but do not fuse.

Geological Range:
Last occurrence (top): at top of H. helvetica zone (100% up, 92.6Ma, in Turonian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within R. cushmani zone (94.03-95.94Ma, base in Cenomanian stage). Data source: Total of ranges of species in this database

Plot of range and occurrence data:

References:

Loeblich, A. R. & Tappan, H. (1988). Foraminiferal Genera and Their Classification (Volume I-II). Van Nostrand Reinhold Co., New York. 1-1059. gs


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Helvetoglobotruncana compiled by the pforams@mikrotax project team viewed: 12-12-2023

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