pforams@mikrotax - Pseudoglobigerinella

Citation: Pseudoglobigerinella Olsson and Pearson 2006

Type species: Globigerina wilsoni bolivariana Petters, 1954.

Taxonomic discussion: The inflated, involute test of Pseudoglobigerinella bolivariana, which becomes planispiral in the final whorl, is unlike any other Paleogene species. Its homeomorphy (in terms of gross morphology) with the Neogene species Hastigerina (Hastigerina) siphonifera ( =Globigerinella siphonifera) led Blow (1979) to questionably place it in Hastigerina although he recognized that future study might provide criteria whereby bolivariana could be placed in a new genus. In fact, the wall textures of bolivariana and siphonifera are quite different from one another (see Olsson and Hemleben, this volume). Globigerinella siphonifera has a bulloides-type wall, and seems to have shared a common ancestor with Globigerina in the upper Oligocene. Pseudoglobigerinella bolivariana, on the other hand, has a highly porous, reticulate Clavigerinella-type wall that develops a thickened crust. Furthermore, there is no known phylogenetic linkage between the two species; bolivariana is unknown in levels above the middle Eocene, whereas siphonifera evolved from G. praesiphonifera in the upper Miocene.
Hillebrandt (1976) first proposed that “Subbotina inaequispira” (= Parasubbotina inaequispira) was the ancestral species to Pseudohastigerina globulosa Hillebrandt ( =Pseudoglobigerinella bolivariana). Blow (1979) also regarded inaequispira as the ancestral species of the lineage, leading to bolivariana through Globorotalia (Turborotalia) griffinae Blow ( =Parasubbotina griffinae). Both Blow (1979) and Toumarkine and Luterbacher (1985) made the interesting observation that inaequispira also gave rise to the Clavigerinella lineage at about the same time (i.e., Biochron E7). The high porosity, reticulate, Clavigerinella-type wall texture of both Clavigerinella and Pseudoglobigerinella n. gen. is shared with P. inaequispira, in which it apparently first developed. [Olsson et al. 2006]

Distinguishing features: Inflated, nearly involute, globular test, asymmetrical equatorial aperture; wall reticulate, Clavigerinella-type wall texture. May show uncoiling.

Description

Diagnostic characters: Pseudoglobigerinella n. gen. is identified by its inflated, nearly involute, globular test, asymmetrical equatorial aperture, and the reticulate, Clavigerinella-type wall texture and thickened crust. A tendency towards uncoiling occurs in some morphotypes of the genus.
[Olsson et al. 2006]

Wall type: Normal perforate, spinose, high porosity, reticulate, Clavigerinella-type wall structure, covered by a thick crust in adult stage. [Olsson et al. 2006]

Test morphology: Globular, nearly involute, asymmetrically planispiral in adult stage (juvenile stage
very low trochospiral), slightly lobulate in outline, chambers globular; 4-5 globular, embracing chambers in final whorl, increasing rapidly in size, ultimate chamber much inflated, sutures moderately depressed, straight, umbilicus small and often covered by ultimate chamber; in edge view chambers globular in shape, slightly embracing, aperture asymmetrically equatorial, varying from a low arch to a high distinctive arch, bordered by an imperforate rim and sometimes by a narrow lip that broadens on both sides towards the center of the coil.
Size: Maximum diameter of type species 0.52 mm, thickness 0.40 mm.
ETYMOLOGY.— Named for its resemblance to modern Globigerinella.
[Olsson et al. 2006]

Biogeography and Palaeobiology

Most likely ancestor: Parasubbotina - at confidence level 0 (out of 5). Data source: .

Biostratigraphic distribution

Geological Range:
Last occurrence (top): near top of Lutetian Stage (89% up, 41.9Ma, in Lutetian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Ypresian Stage (71% up, 50.2Ma, in Ypresian stage). Data source: Total of range of species in this database

Primary source for this page: Olsson et al. 2006 - Eocene Atlas, chap. 5, p. 105

References:

Blow, W.H., (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea), 2. E. J. Brill, Leiden, 1413 pp.

Hillebrandt, A., von (1976). Los foraminiferos planctonicos, nummulitidos y coccolitoforidos de la zona de Globorotalia palmerae del Cuisiense (Eoceno inferior) en el SE de Espana, (Provincias de Murcia y Alicante. Revista Española de Micropaleontología, 8(3): 323-394.

Olsson, R.K.; Pearson, P.N. & Huber, B.T., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Catapsydrax, Globorotaloides, Guembelitrioides, Paragloborotalia, Parasubbotina, and Pseudoglobigerinella n. gen. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera. Cushman Foundation Special Publication. 41 Allen Press, Lawrence, Kansas, pp. 67-110.

Petters, V., (1954). Tertiary and Upper Cretaceous foraminifera from Colombia, S. A. Contributions from the Cushman Foundation for Foraminiferal Research, 5(1): 37-41.

Pseudoglobigerinella

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

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Daughter taxa: (blue => in age window 0-800Ma)
			Pseudoglobigerinella bolivariana Test compact, nearly involute, globular; aperture asymmetrical equatorial; Clavigerinella-type reticulate wall texture and thickened crust.
			Pseudoglobigerinella sp. Specimens which cannot be assigned to established species