pforams@mikrotax - Hastigerinoides alexanderi pforams@mikrotax - Hastigerinoides alexanderi

Hastigerinoides alexanderi


Classification: pf_mesozoic -> Globigerinelloididae -> Hastigerinoides -> Hastigerinoides alexanderi
Sister taxa: H. alexanderi, H. atlanticus, H. clavatus, H. sp.

Taxonomy

Citation: Hastigerinoides alexanderi (Cushman, 1931)
taxonomic rank: Species
Basionym: Hastigerinella alexanderi

Type images:

Original description: "Test nearly planispiral, the early chambers largely concealed from both sides; chambers greatly expanded in the adult coil, consisting typically of 6 chambers, but occasionally only 5, the earliest ones subglobular, but quickly expanding and greatly elongating, tapering rathe uniformly to a pointed outer end; suturs distinct, slightly depressed; wall nearly smooth, or finely hispid; aperture nearly at the peripheral margin at the base of the chambers, with a very slight lip."

Entries in the Catalog of original descriptions: Hastigerinella alexanderi


Emended description:

Georgescu & Huber, 2008, p. 53: "Test planispiral or, more rarely, very low trochospiral. Earlier chambers are globular, the last three to five are radially very elongate, tapering, resembling tubulospines; five to six chambers in the last whorl. Sutures are distinct, depressed, straight or slightly curved and radial on both sides of the test. Main aperture is equatorial to sub-equatorial in position, extending into the umbilicus, in the shape of a medium-high to high arch and bordered by a wide lip. Relict apertures can be present in the umbilical areas. Pustules are present only on the earlier chambers of the last whorl; the last-formed chambers are smooth. Test wall calcitic, hyaline, finely perforate; pore diameter in adult specimens is between 1.6 and 1.8 microns." [copied from Chronos database]

Character matrix
test outline:Stellatechamber arrangement:Planispiraledge view:Hourglassaperture:Equatorial
sp chamber shape:Elongatecoiling axis:Very lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Elongateumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:Relict
spiral sutures:Moderately depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:4.5-5.5 N.B. These characters are used for advanced search. N/A - not applicable

Geological Range:
Last occurrence (top): within D. asymetrica zone (83.65-85.60Ma, top in Santonian stage). Data source: [copied from Chronos database]
First occurrence (base): within D. concavata zone (85.60-89.75Ma, base in Turonian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

References:

Cushman, J. A. (1931a). Hastigerinella and other interesting foraminifera from the Upper Cretaceous of Texas. Contributions from the Cushman Laboratory for Foraminiferal Research. 7(4): 17-19. gs

Georgescu, M. D. & Huber, B. T. (2008). Taxonomic re-evaluation and phylogeny of the stellate planktonic foraminiferal genus Hastigerinoides Brönnimann, 1952. Journal of Foraminiferal Research. 38: 52-58. gs

Masters, B. A. (1977a). Mesozoic planktonic foraminifera. In, Ramsay, A. T. S. (ed.) Oceanic Micropaleontology. Academic Press, London 1: 301-731. gs


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Hastigerinoides alexanderi compiled by the pforams@mikrotax project team viewed: 19-6-2024

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