pforams@mikrotax - Racemiguembelina

pforams@mikrotax - Racemiguembelina pforams@mikrotax - Racemiguembelina

Racemiguembelina

Classification: pf_mesozoic -> Heterohelicidae -> Racemiguembelina
Sister taxa: Heterohelix, Spiroplecta ⟩⟨ Braunella, Hendersonites, Huberella, Laeviheterohelix, Planoheterohelix, Protoheterohelix, Pseudoguembelina, Pseudotextularia ⟩⟨ Planoglobulina, Ventilabrella, Gublerina, Praegublerina, Sigalia, Racemiguembelina ⟩⟨ Lunatriella, Rectoguembelina, Zeauvigerina

Daughter taxa (time control age-window is: 0-800Ma)
			Racemiguembelina fructicosa
			Racemiguembelina powelli
			Racemiguembelina sp. Specimens which cannot be assigned to established species

Taxonomy

Citation: Racemiguembelina Montanaro Gallitelli 1957

taxonomic rank: Genus

Type species: Guembelina fructicosa Egger, 1902

Original description: Diagnosis: Test calcareous, conical in shape; rarely planispiral in the early stage, later biserial, increasing regularly and equally in thickness and breadth, finally proliferated with a varying number of additional globular chambers, the last of which form a crown at the top of the test and are provided with a series of arcuate, basal apertures. No spiral arrangement of the adult chambers is evident. Ornamentation consists of longitudinally developed costae.

Entries in the Catalog of original descriptions: Racemiguembelina

Distinguishing features:
Parent taxon (Heterohelicidae): Aperture symmetrical, ranging from a low slit to a high arch at the base of the final chamber, becoming terminal in uniserial taxa.
This taxon: Test initially biserial, becomes conical with proliferation of multiple globular chambers forming a crown at top of test

Morphology:

Test subconical, microspheric early stage may be planispiral and later stage biserial, regularly enlarging globular chambers proliferate in the later stage in a plane perpendicular to the earlier plane of growth, forming an open cone only partially joined by a bridgelike coverplate, sutures depressed; wall calcareous, hyaline, surface with longitudinal irregular to discontinuous imperforate costae, alternating with distinctly perforate areas of the wall, coverplate over the apertures with much finer perforations; aperture consists of broad arched interiomarginal openings directed toward the umbilicus on all chambers in the final whorl, apertures may be partially covered by the bridge like cover plate that extends from one apertural face to another in the same series of chambers, each coverplate bordered by large infralaminal accessory apertures.

Geological Range:
Last occurrence (top): at top of P. hariaensis zone (100% up, 66.4Ma, in Maastrichtian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within G. gansseri zone (71.73-73.80Ma, base in Campanian stage). Data source: Total of ranges of species in this 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
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Heterohelicidae

References:

Loeblich, A. R. & Tappan, H. (1988). Foraminiferal Genera and Their Classification (Volume I-II). Van Nostrand Reinhold Co., New York. 1-1059. gs

Racemiguembelina compiled by the pforams@mikrotax project team viewed: 16-10-2024

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