Taxonomy
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
Character matrix
test outline: | Lobate | chamber arrangement: | Planispiral | edge view: | Hourglass | aperture: | Equatorial |
sp chamber shape: | Globular | coiling axis: | Very low | periphery: | N/A | aperture border: | Thin lip |
umb chbr shape: | Globular | umbilicus: | Wide | periph margin shape: | Broadly rounded | accessory apertures: | Relict |
spiral sutures: | Moderately depressed | umb depth: | Deep | wall texture: | Finely pustulose | shell porosity: | - |
umbilical or test sutures: | Moderately depressed | final-whorl chambers: | 7-10 | 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 (73.80-74.20Ma, top in Campanian stage). Data source: Huber et al 2022
First occurrence (base): within G. elevata zone (79.33-83.65Ma, base in Campanian stage). Data source: Huber et al 2022
Plot of range and occurrence data:
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. (2022b). 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 References:
![]() |
Planohedbergella impensa compiled by the pforams@mikrotax project team viewed: 13-2-2025
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 |
This policy contains information about your privacy. By posting, you are declaring that you understand this policy:
This policy is subject to change at any time and without notice.
These terms and conditions contain rules about posting comments. By submitting a comment, you are declaring that you agree with these rules:
Failure to comply with these rules may result in being banned from submitting further comments.
These terms and conditions are subject to change at any time and without notice.
Comments