Planoglobanomalina


Classification: pf_cenozoic -> Globanomalinidae -> Planoglobanomalina
Sister taxa: Globanomalina, Muricohedbergella, Planoglobanomalina, Pseudohastigerina, Turborotalia
Daughter taxa: (blue => in age window 0-800Ma)
Planoglobanomalina pseudoalgeriana
Test loosely coiled, evolute, and compressed; 9-10 chambers in the final whorl, last three chambers showing a trend towards uncoiling.
Planoglobanomalina sp.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Planoglobanomalina Olsson and Hemleben, 2006
Rank: Genus
Type species: Planoglobanomalina pseudoalgeriana Olsson & Hemleben 2006
Taxonomic discussion: Based on his study of the early Eocene KANE 9 core in the eastern equatorial Atlantic Ocean, Blow (1979) proposed that Pseudohastigerina danvillensis (Howe and Wallace) had an independent line of descent from other members of the genus, which he proposed was from Globorotalia (Turborotalia) planoconica Subbotina (= Globanomalina planoconica in this work), in contradiction to the views of Cordey and others (1969) who had considered P. danvillensis as a junior synonym of P. micra. He concurred with their view that P. micra had evolved from Pseudohastigerina wilcoxensis (Cushman) and that P. wilcoxensis, in turn, had evolved from Globanomalina at the base of Zone P6. Specialists have ignored Blow’s suggestion that there were two independent origins for the genus Pseudohastigerina. However, our examination of assemblages from ODP Hole 865B from the equatorial Pacific and recent drill-cores from Tanzania (Pearson and others, 2004) confirm Blow’s earlier observations of a separate origin for a planispiral morphotype in the early Eocene that is morphological similar to Pseudohastigerina. This necessitates the naming of a new genus, because unlike Blow (1979) we do not permit polyphyletic form -genera in our classification.
Blow derived Pseudohastigerina danvillensis from Globorotalia (Turborotalia) planoconica ( =Globanomalina planoconica) and illustrated specimens of G. planoconica from Zone E8 (see discussion below on the taxonomy of planoconica) that showed apertures that extended slightly onto the spiral side as well as specimens of P. danvillensis showing equatorial apertures. His observations do indeed illustrate a linkage between these Eocene morphotypes of G. planoconica and the derivation of a planispiral morphology. He was, however, incorrect in his identification of Pseudohastigerina danvillensis, which is a junior synonym of Pseudohastigerina micra (see discussion below). We have also observed a similar transitional morphology in ODP Hole 865B and Tanzania Drilling Project Site 2, but starting in Zone E6. The planispiral morphotype is more openly coiled and planispirally evolute with a tendency towards uncoiling of the last few chambers in the ultimate whorl (Plate 14.2, Figs. 5, 8-10). The test is much compressed and the chambers in axial view have a pinched periphery and show an ogyval shape that Blow emphasized as a distinguishing characteristic in separating his P. danvillensis ( =P. micra) from P. micra. Morphotypes with 9 to 10 elongated chambers in the ultimate whorl are closely homeomorphic with the Aptian planispiral species Globigerinelloides algerianus (Plate 14.2, Fig. 5). These morphotypes do not appear to range above Zone E8. Other characteristics of all these morphotypes include recurved sutures and somewhat broad apertural lips that fuse with previous lips to form an apertural rim around the umbilicus. In some specimens, as was noted
by Blow, relict apertures open where the lips are not completely fused.
The planispiral to almost planispiral morphotypes derived from Globanomalina planoconica are herein placed in the new genus Planoglobanomalina and the type species for the new genus is the new species Planoglobanomalina pseudoalgeriana.
[Olsson & Hemleben 2006]

Catalog entries: Planoglobanomalina

Distinguishing features: Planispiral, compressed, loosely coiled, numerous chambers in final whorl, last 1-3 chambers uncoiling.
Aperture equatorial, oval-shaped with broad lip.

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.
They are being edited as the site is developed and comments on them are especially welcome.

Description


Wall type: Smooth, normal perforate. [Olsson & Hemleben 2006]

Biogeography and Palaeobiology


Phylogenetic relations: Planoglobanomalina n. gen. evolved from Globanomalina planoconica and left no descendants.
[Olsson & Hemleben 2006]

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

Biostratigraphic distribution

Geological Range:
Notes: Zone E6 to Zone E8.
[Olsson & Hemleben 2006]
Last occurrence (top): in lower part of Lutetian Stage (24% up, 46.2Ma, in Lutetian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Ypresian Stage (66% up, 50.6Ma, in Ypresian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Olsson & Hemleben 2006 - Eocene Atlas, chap. 14, p. 418

References:

Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. gs

Olsson, R. K. & Hemleben, C. (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Globanomalina, Planoglobanomalina n. gen and Pseudohastigerina. In, Pearson, P. N. , Olsson, R. K. , Hemleben, C. , Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 14): 413-432. gs V O

Pearson, P. N. et al. (2004). Paleogene and Cretaceous sediment cores from the Kilwa and Lindi areas of coastal Tanzania: Tanzania Drilling Project Sites 1–5. Journal of African Earth Sciences. 39: 25-62. gs


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Planoglobanomalina compiled by the pforams@mikrotax project team viewed: 25-10-2020

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