Protentelloides


Classification: pf_cenozoic -> Globigerinidae -> Protentelloides
Sister taxa: Beella, Globigerina, Globigerinella, Protentella, Quiltyella, Ciperoella, Globigerinoides, Globigerinoidesella, Globoturborotalita, Orbulina, Praeorbulina, Sphaeroidinella, Sphaeroidinellopsis, Trilobatus, Turborotalita, Dentoglobigerina, Globoquadrina, Catapsydrax, Clavatorella, Paragloborotalia, Protentelloides, Eoglobigerina, Globigerinatheka, Globorotaloides, Guembelitrioides, Orbulinoides, Parasubbotina, Pseudoglobigerinella, Subbotina,
Daughter taxa: (blue => in age window 0-300Ma)

Like P. primitivus but with more evolute, near-planispiral coiling; apertural system, more variable and complex, with tendency to become ‘cribrate’.


Large, laterally compressed, low trochospiral/pseudoplanispiral, 4-6 chambers in the final whorl, final chamber reduced and bulla-like, sutures depressed, straight to curved; aperture an elongated slit at the base of the bulla-like final chamber.



Taxonomy

Citation:

Protentelloides Zhang and Scott, 1995

Rank: genus
Type species: Protentelloides dalhousiei Zhang and Scott (1995).
Taxonomic discussion: The appearance of this short ranging genus (1-2 million years) in the upper Oligocene is a prominent event in the evolution of this group. It may have biostratigraphic potential, however to date, Protentelloides has not been recorded outside its type location in the eastern equatorial Atlantic Ocean, Sierra Leone Rise, DSDP Hole 366A (Zhang and Scott, 1995) and ODP Hole 667A (Spezzaferri, 1994). Zhang and Scott (1995) suggested that Protentelloides dalhousiei maybe the ancestor of Clavatorella bermudezi. It is easy to see the morphological resemblance but a direct connection to C. bermudezi seems unlikely since that taxon does not appear until the early Miocene, approximately 7 million years after the Protentelloides horizon, and intermediates between Globorotaloides hexagonus and C. bermudezi have been described (Pearson, 1995). We suggest Protentelloides dalhousiei represents a sub-clavate homeomorph of C. bermudezi. [Coxall & Spezzaferri 2018]

Catalog entries: Protentelloides;

Type images:

Distinguishing features: Laterally compressed, often with bulla/bullate final chamber

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


Diagnostic characters: Protentelloides is distinguished from Globorotaloides in the lateral flattening and spreading of the test and the equatorial positioning of the bulla or bulla-like final chamber, and aperture(s). Protentelloides differs from Clavatorella and Protentella in lacking digitate chambers. Protentelloides also has a distinctive bulla-like final chamber, projecting imperforate lip and a cancellate Globorotaloides-wall whereas Protentella has a more finely ‘reticulate’ wall. Protentelloides differs from Globigerinella in having flattened chambers. The system of accessory apertures is reminiscent of the ‘cribrate’ equatorial aperture of late Eocene genus Cribrohantkenina. [Coxall & Spezzaferri 2018]

Wall type: Normal perforate, coarsely cancellate, sacculifer-type to ruber/sacculifer-type. Possibly spinose. [Coxall & Spezzaferri 2018]

Test morphology: Laterally compressed, low trochospiral/pseudoplanispiral; lobate to strongly lobate, 5-7 chambers in the final whorl, increasing rapidly in size; chambers flatten towards the center of the test; sutures on both sides almost radial, depressed, straight, becoming curved to sigmoidal; final chamber is typically reduced in size, bulla-like, centered at the equatorial margin and highly variable in morphology, ranging from globular and protruding to flattened and unobtrusive; primary aperture highly variable, also equatorially centered, ranging from a low extraumbilical to equatorial, symmetrical or asymmetrical arch, a long equatorial slit extending up the final chamber face, a bi-radiate equatorial arch (with one ray extending into the umbilical region). The aperture is bordered by an imperforate flap-like lip that may fuse to subdivide the primary aperture, or be perforated by one or more circular or elongated accessory apertures, reminiscent of the ‘cribrate’ supplementary aperture system of late Eocene Cribrohantkenina. [Coxall & Spezzaferri 2018]

Biogeography and Palaeobiology

Most likely ancestor: Globorotaloides - at confidence level 3 (out of 5). Data source: Coxall & Spezzaferri 2018 f4.1.

Biostratigraphic distribution

Geological Range:
Last occurrence (top): in mid part of Aquitanian Stage (48% up, 21.8Ma, in Aquitanian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Chattian Stage (61% up, 25Ma, in Chattian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Coxall & Spezzaferri 2018 - Olig Atlas chap.4 p.115

References:

Coxall, H.K. & Spezzaferri, S., (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene Catapsydrax, Globorotaloides, and Protentelloides. In: Wade, B.S. et al. (Editors), Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research Special Pulbication. 46, pp. 79-125.

Pearson, P.N.P., (1995). Planktonic foraminifer biostratigraphy and the development of pelagic caps on guyots in the Marshall Islands group. Proceedings of the Ocean Drilling Program, Scientific Results, 144: 21-59.

Spezzaferri, S., (1994). Planktonic foraminiferal biostratigraphy and taxonomy of the Oligocene and lower Miocene in the oceanic record. An overview. Palaeontographia Italica, 81: 1-187.

Zhang, J. & Scott, D.B., (1995). New planktonic foraminiferal genus and species from the upper Oligocene, DSDP Hole 366A, Leg 41. Micropaieontology, 41(1): 77-83.


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Protentelloides compiled by the pforams@mikrotax project team viewed: 15-12-2018

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