Taxonomy
Original description: Test is small, consisting of 11-13 biserially arranged chambers throughout. Proloculus is small (9.1-14.3 microns) and followed by a slightly larger second chamber. Earlier chambers are subglobular, those of the adult portion of the test subglobular to reniform and oblique to the test axis of growth. Sutures are straight to slightly curved, distinct and depressed and oblique to the test axis of growth. Tests are symmetrical in edge view, with periphery broadly rounded. Aperture is an interiomarginal, low- to medium-high arch bordered by two unequally developed periapertural flanges. Chamber surface is smooth. Test wall is calcitic, hyaline, and nannoperforate to microperforate; pore diameter ranges 0.4-0.9 microns.
Entries in the Catalog of original descriptions: Protoheterohelix obscura
Diagnostic characters:
Emended description:
Character matrix
| test outline: | Triangular | chamber arrangement: | Biserial | edge view: | Compressed | aperture: | Interiomarginal |
| sp chamber shape: | Reniform | coiling axis: | N/A | periphery: | N/A | aperture border: | Thin flange |
| umb chbr shape: | Reniform | umbilicus: | N/A | periph margin shape: | Broadly rounded | accessory apertures: | N/A |
| spiral sutures: | Moderately depressed | umb depth: | N/A | wall texture: | Smooth | shell porosity: | |
| umbilical or test sutures: | Moderately depressed | final-whorl chambers: | 2-2 | N.B. These characters are used for advanced search. N/A - not applicable | |||
Geological Range:
Last occurrence (top): within H. helvetica zone (92.51-93.52Ma, top in Turonian stage). Data source: [copied from Chronos database]
First occurrence (base): within P. appenninica zone (100.50-101.92Ma, base in Albian stage). Data source: [copied from Chronos database]
Plot of range and occurrence data:
Georgescu, M. D. & Huber, B. T. (2009). Early evolution of the Cretaceous serial planktic foraminifera (late Albian-Cenomanian). Journal of Foraminiferal Research. 39: 335-360. gs O Haynes, S., Huber, B. T. & MacLeod, K. G. (2015). Evolution and phylogeny of mid-Cretaceous (Albian-Coniacian) biserial planktic foraminifera. Journal of Foraminiferal Research. 44: 42-81. gs Huber, B. T., Watkins, D. K. & Petrizzo, M. R. (2026). Integrated Albian-Cenomanian calcareous nannofossil and planktic
foraminiferal biostratigraphy and paleoceanography of southern high
latitude IODP sites drilled on Naturaliste Plateau (southeast Indian
Ocean). Cretaceous Research. 189[2027]: 1-43. gs OReferences:

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Protoheterohelix obscura compiled by the pforams@mikrotax project team viewed: 9-10-2026
Short stable page link: https://mikrotax.org/pforams/index.php?id=110446 Go to Archive.is to create a permanent copy of this page - citation notes |
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