pforams@mikrotax - Planohedbergella impensa

Planohedbergella impensa


Classification: pf_mesozoic -> Globigerinelloididae -> Planohedbergella -> Planohedbergella impensa
Sister taxa: P. aspera, P. circularis, P. escheri, P. impensa, P. messinae, P. multispina, P. prairiehillensis, P. subcarinata, P. ultramicra, P. yaucoensis

Taxonomy

Citation: Planohedbergella impensa (Sliter 1977)
Rank: species
Basionym: Globigerinelloides impensus Sliter 1977

Type images:

Original description: Test free, planispiral, biumbilicate, partially evolute, equatorial periphery lobate, axial periphery rounded. Chambers 8 to 10 in final whorl, equatorially flattened, increasing gradually in size, final chambers generally ovate, ultimate chamber often reduced in size. Sutures distinct, depressed radial, straight to gently curved. Wall calcareous, finely perforate, surface pustulose on early chambers of final whorl, final few chambers nearly smooth. Aperture a broad, low, interiomarginal, equatorial arch, pordered above by a narrow lip. Relic apertures and relic apertural flaps distinct. From Ellis & Messina: "Test free, planispiral, biumbilicate, partially evolute, equatorial periphery lobate, axial periphery rounded. Chambers 8 to 10 in final whorl, equatorially flattened, increasing gradually in size, final chambers generally ovate, ultimate chamber often reduced in size. Sutures distinct, depressed radial, straight to gently curved. Wall calcareous, finely perforate, surface pustulose on early chambers of final whorl, final few chambers nearly smooth. Aperture a broad, low, interiomarginal, equatorial arch, bordered above by a narrow lip. Relic arpertures and relic apertural flaps distinct. "Largest diameter of holotype 0.32 mm. Paratypes range from 0.28 to 0.43 mm. "Remarks. - This large plantonic species characterized by the numerous flattened chambers occurs consistently in the late Campanian smaples of Leg 36. Globigerinelloides impensus Sliter somewhat resembles Globigerinelloides alvarezi (Etemod Olvera) [Planomalina alvarezi, 1959] originally described from the Campanian-Maestrichtian of Mexico. It differs, however, in the larger size, compressed test, slightly curved sutures, and less highly arched aperture. "The new species differs from Globigerinelloides bolli Pessagno in its larger size, more numerous, more compressed chambers, gently curved sutures, and pustulose surface."

Entries in the Catalog of original descriptions: Globigerinelloides impensus


Emended description:


Morphology:

Wall type:

Size:

Character matrix
test outline:Lobatechamber arrangement:Planispiraledge view:Hourglassaperture:Equatorial
sp chamber shape:Globularcoiling axis:Very lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Globularumbilicus:Wideperiph margin shape:Broadly roundedaccessory apertures:Relict
spiral sutures:Moderately depressedumb depth:Deepwall texture:Finely pustuloseshell porosity:-
umbilical or test sutures:Moderately depressedfinal-whorl chambers:7.0-10.0 N.B. These characters are used for advanced search. N/A - not applicable

Most likely ancestor: Planohedbergella ultramicra - at confidence level 2 (out of 5). Data source: Huber et al. 2022 fig. 2.

Geological Range:
Last occurrence (top): within G. aegyptiaca zone (72.97-74.00Ma, top in Campanian stage). Data source: Huber et al 2022
First occurrence (base): within G. elevata zone (79.20-84.19Ma, base in Santonian stage). Data source: Huber et al 2022

Plot of range and occurrence data:

References:

Huber, B. T. (1990). Maestrichtian planktonic foraminifer biostratigraphy of the Maud Rise (Weddell Sea, Antarctica): ODP Leg 113 Holes 689B and 690C. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 489-513. gs

Huber, B. T., Petrizzo, M. M. & Falzoni, F. (2022). Taxonomy and phylogeny of Albian–Maastrichtian planispiral planktonic foraminifera traditionally assigned to Globigerinelloides. Micropaleontology. 68(2): 117-183. gs

Sliter, W. V. (1977). Cretaceous foraminifers from the southwestern Atlantic Ocean, Leg 36, Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project. 36: 519-573. gs


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Planohedbergella impensa compiled by the pforams@mikrotax project team viewed: 5-12-2022

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Short stable page link: https://mikrotax.org/pforams/index.php?id=110135 Go to Archive.is to create a permanent copy of this page - citation notes



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