Specimens which cannot be assigned to established species
| 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
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.
Emended description:
Morphology:
Wall type:
Size:
Geological Range:
Last occurrence (top): in lower part of Turonian Stage (32% up, 92.6Ma, in Turonian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Cenomanian Stage (69% up, 95.9Ma, in Cenomanian stage). Data source: Total of range of species in this database
Plot of range and occurrence data:
Loeblich, A. R. & Tappan, H. (1988). Foraminiferal Genera and Their Classification (Volume I-II). Van Nostrand Reinhold Co., New York. 1-1059. gsReferences:
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Helvetoglobotruncana compiled by the pforams@mikrotax project team viewed: 8-2-2023
Short stable page link: https://mikrotax.org/pforams/index.php?id=110274 Go to Archive.is to create a permanent copy of this page - citation notes |
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