pforams@mikrotax - Planoheterohelix olssoni

pforams@mikrotax - Planoheterohelix olssoni pforams@mikrotax - Planoheterohelix olssoni

Planoheterohelix olssoni

Classification: pf_mesozoic -> Heterohelicidae -> Planoheterohelix -> Planoheterohelix olssoni
Sister taxa: P. globulosa, P. moremani, P. olssoni, P. papula, P. paraglobulosa, P. planata, P. postmoremani, P. praenuttallii, P. reussi, P. rumseyensis ⟩⟨ P. labellosa, P. sphenoides, P. stenopos, P. vistulaensis, P. sp.

Taxonomy

Citation: Planoheterohelix olssoni (Georgescu, 2000)

Rank: Species

Basionym: Heterohelix olssoni

Taxonomic discussion: Heterohelix olssoni n.sp. differs from H. moremani (Cushman) in having (1) larger planispirally enrolled stage, (2) reduced number of paired chambers in the biserial part of the test, (3) greater values of the W/Lmax ans Lps/Lmax ratios (4) absence of striae on the chamber surface and (5) generally smaller size. While Heterohelix moremani (Cushman) is a typical representative of the genus while, H. olssoni n.sp. appears to be a descendant of the primitive heterohelicids, as it exhibits large planispirally enrolled earlier test stage. [copied from Chronos database]

Type images:

holotype: H. olssoni
holotype: H. olssoni

Original description: Stout test having well developed early planispirally enrolled test. The primary stage is followed by a biserial one consisting of two to (rarely) tree pairs of chambers. Chambers subglobular to globular, sometimes slightly dorso-ventrally flattened. Sutures straight to slightly depressed. Wall finely perforate. Test surface is smooth, unornamented, lacking any trace of striae. Primary aperture, a low arch at the base of the last formed chamber, is bordered by a narrow imperforate lip.

Entries in the Catalog of original descriptions: Heterohelix olssoni

Character matrix
test outline: Subtriangular chamber arrangement: Biserial edge view: Compressed aperture: Interiomarginal
sp chamber shape: Globular coiling axis: N/A periphery: N/A aperture border: Thin lip
umb chbr shape: Globular umbilicus: N/A periph margin shape: Broadly rounded accessory apertures: N/A
spiral sutures: Flush umb depth: N/A wall texture: Smooth shell porosity:
umbilical or test sutures: Flush final-whorl chambers: 2.0-2.0 N.B. These characters are used for advanced search. N/A - not applicable

Geological Range:
Last occurrence (top): within T. reicheli zone (95.94-96.08Ma, top in Cenomanian stage). Data source: [copied from Chronos database]
First occurrence (base): within T. reicheli zone (95.94-96.08Ma, base in Cenomanian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
(NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Planoheterohelix

References:

Georgescu, M. D. (2000). Late Albian-Turonian planktonic foraminifera in the Romanian western Black Sea offshore. Revista Española de Micropaleontología. 32: 157-173. gs

Planoheterohelix olssoni compiled by the pforams@mikrotax project team viewed: 25-3-2023

Taxon Search:

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AphiaID: 1034792 Nomenclatural data on WoRMS
Short stables page link: https://mikrotax.org/pforams/index.php?id=110403 Go to Archive.is to create a permanent copy of this page - citation notes

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test outline:	Subtriangular	chamber arrangement:	Biserial	edge view:	Compressed	aperture:	Interiomarginal
sp chamber shape:	Globular	coiling axis:	N/A	periphery:	N/A	aperture border:	Thin lip
umb chbr shape:	Globular	umbilicus:	N/A	periph margin shape:	Broadly rounded	accessory apertures:	N/A
spiral sutures:	Flush	umb depth:	N/A	wall texture:	Smooth	shell porosity:
umbilical or test sutures:	Flush	final-whorl chambers:	2.0-2.0	N.B. These characters are used for advanced search. N/A - not applicable