Praemurica pseudoinconstans


Classification: pf_cenozoic -> Truncorotaloididae -> Praemurica -> Praemurica pseudoinconstans
Sister taxa: P. uncinata, P. inconstans, P. pseudoinconstans, P. taurica, P. nikolasi, P. sp.,

Taxonomy

Citation: Praemurica pseudoinconstans (Blow 1979)
Rank: Species
Basionym: Globorotalia (Turborotalia) pseudoinconstans
Synonyms:
Taxonomic discussion: Praemurica pseudoinconstans is a fairly common species that may be confused with the less common Parasubbotina pseudobulloides (Plummer). Indeed, Blow (1979) carefully distinguished the two species and selected as a paratype a specimen from the Clayton Formation, Alabama, previously identified by Loeblich and Tappan (1957a) as P.
pseudobulloides. The chambers in P. pseudobulloides increase more rapidly in size and are more inflated than in P. pseudoinconstans. Parasubbotina pseudobulloides is spinose in contrast to Ppseudoinconstans, which is nonspinose. The meandriform pattern of the interpore ridges noted by Blow (1979) is due to the Neogloboquadrina dutertrei-like wall texture observed in this species under SEM. In this type of wall texture, the pores are often not isolated from one another by interpore ridges as in P. pseudobulloides. Except for their general appearance, the two wall textures are fundamentally different. [Olsson et al. 1999]

Catalog entries: Globorotalia (Turborotalia) pseudoinconstans

Type images:

Distinguishing features: Like P. taurica but with increased rate of expansion of the final few chambers; also apertural lip less pronounced.

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: The 5 to 5½ chambers of the ultimate whorl increase gradually in size at first but then more rapidly in the final few chambers. The ultimate chamber may be offset slightly towards the umbilical side. The aperture is a high rounded arch, bordered by a narrow lip that broadens towards the umbilicus although not as pronounced as in P. taurica. The cancellate wall texture is weakly developed and difficult to view with the light microscope, especially where the preservation is poor. The pores which lie at the base of the cancellate ridges average about 1 µm in diameter at the narrowest point. The walls are about 4 µm in thickness and the overall size of the test is up to 300 µm across. [Olsson et al. 1999]

Character matrix

test outline:Subcircularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Thick lip
umb chbr shape:Inflatedumbilicus:Wideperiph margin shape:Broadly roundedaccessory apertures:Relict
spiral sutures:Strongly depressedumb depth:Deepwall texture:Pore moundsshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Strongly depressedfinal-whorl chambers:6.0-7.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Originally described from DSDP
Site 47, Shatsky Rise, northwestern Pacific Ocean. It also occurs in Alabama and in the South Atlantic Ocean at DSDP Site 356. [Olsson et al. 1999]
Aze et al. 2011 summary: Low to middle latitudes; based on Olsson et al. (1999)

Isotope paleobiology: No data available. [Olsson et al. 1999]
Aze et al. 2011 ecogroup 2 - Open ocean mixed-layer tropical/subtropical, without symbionts. Based on δ13C lighter than species with symbionts; also with relatively light δ18O. Sources cited by Aze et al. 2011 (appendix S3): this study

Phylogenetic relations: Evolved from Praemurica taurica in middle Biochron Pa by increasing the rate of expansion of the last few chambers in the ultimate whorl. [Olsson et al. 1999]

Most likely ancestor: Praemurica taurica - at confidence level 4 (out of 5). Data source: Olsson et al. (1999), fig. 5a.
Likely descendants: Praemurica inconstans;

Biostratigraphic distribution

Geological Range:
Notes: Zone Pa to Zone P2. [Olsson et al. 1999]
Last occurrence (top): in lower part of P2 zone (40% up, 62.5Ma, in Danian stage). Data source: Olsson et al. (1999), fig. 5a
First occurrence (base): in upper part of Pa zone (60% up, 65.8Ma, in Danian stage). Data source: Olsson et al. (1999), fig. 5a

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 74

References:

Berggren, W. A. (1965). Some Problems of Paleocene-Lower Eocene Planktonic Foraminiferal Correlations. Micropaleontology. 11: 278-300. gs

Berggren, W. A. (1992). Paleogene planktonic foraminifer magnetobiostratigraphy of the southern Kerguelen Plateau (sites 747-749). Proceedings of the Ocean Drilling Program, Scientific Results. 551-568. gs

Bermudez, P. J. (1961). Contribucion al estudio de las Globigerinidea de la region Caribe-Antillana (Paleoceno-Reciente). Editorial Sucre, Caracas. 1119-1393. gs

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

Bolli, H. M. (1957d). The genera Globigerina and Globorotalia in the Paleocene-Lower Eocene Lizard Springs Formation of Trinidad. In, Loeblich, A. R. , Jr. , Tappan, H. , Beckmann, J. P. , Bolli, H. M. , Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 61-82. gs

Hillebrandt, A. , von (1962). Das Paleozän und seine Foraminiferenfauna im Becken von Reichenhall und Salzburg. Abhandlungen Bayerischen Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Klasse, Neue Folge. 108: 1-182. gs

Khalilov, D. M. (1956). 0 pelagicheskoy faune foraminifer Paleogenovykh otlozheniy Azerbaydzhana [Pelagic Foraminifera of the Paleogene Deposits of the Azerbaizhan SSR]. Trudy Instituta Geologii, Akademiya Nauk Azerbaidzhanskoi SSR. 17: 234-255. gs

Leonov, G. P. & Alimarina, V. (1960). Stratigrafiya i planktonnye foraminifery "perekhodnykh" ot mela k paleogeny sloev tsentral'nogo Predkavkazya [Stratigraphy and Plantonic Foraminifera of the Cretaceous-Paleogene "Transition" Beds of the Central Part of the North Caucasus]. In Problema V: Granitsa melovoi i paleogenovoi sistem. Mezhdunarodnyi Geologicheskii Kongress, XXI Sessiya, Doklady Sovetskikh Geologov, Izdatelstvo Akademiya Nauk. 29-60. gs

Luterbacher, H. P. (1964). Studies in some Globorotalia from the Paleocene and Lower Eocene of the Central Apennines. Eclogae Geologicae Helvetiae. 57: 631-730. gs

Morozova, V. G. (1957). On the Foraminiferal superfamily Globigerinidea, nov. and some of its representatives (in Russian). Doklady Akademii Nauk SSSR. 114(5): 1109-1112. gs

Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. 1-252. gs

Shutskaya, E. K. (1970b). Stratigrafiya, foraminifery i paleogeografiya nizhnego paleogena Kryma, predkavkaz'ya i zapadnoi chadsti srednei azii [Stratigraphy, Foraminifera and Paleogeography of the Lower Paleogene in the Crimea, Precaucasus and the Western Part of Central Asia]. Trudy, Vsesoyuznyi Nauchno-lssledovadetel 'skii Geologorazvedochnyi Neftyanoi Institut (VNIGNI). 70(1): 256-. gs

Stott, L. D. & Kennett, J. P. (1990). The Paleoceanographic and Paleoclimatic signature of the Cretaceous/Paleogene boundary in the Antarctic: Stable isotopic results from ODP Leg 113. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 829-848. gs

Subbotina, N. N. (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres. 2239: 1-144. gs


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Praemurica pseudoinconstans compiled by the pforams@mikrotax project team viewed: 13-11-2019

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Comments (1)

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Chengjie Liu (Houston, US)

It seems to me that the holotype image (right beneath) for Globorotalia pseudoinconstans Blow (1979) fits the concept of Globigerina inconstans Subbotina (1953, holotype, left images). The images for the paratype of Globorotalia pseudoinconstans Blow (1979, central images below) is more primitive and fits the concept of an intermediate form between P. taurica and P. inconstans.

So, if we go with Blow's holotype, Globorotalia pseudoinconstans Blow (1979) would become a junior synonym of Globigerina inconstans Subbotina (1953). Then. left us with a problem: what to do with the more primitive paratype of Globorotalia pseudoinconstans Blow (1979), elevate it to holotype for Praemurica pseudoinconstans (Blow) or create a new species Praemurica praeinconstans or P. posttaurica?

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Jeremy Young (Tonbridge, UK)

Chengjie

I won't attempt to comment on the foram morphology side of this but if you are right then in terms of nomenclatural taxonomy the correct solution would be the second one; pseudoinconstans would become a junior synonym of taurica and if separating all three morphotypes is useful then a new name would be needed for the intermediate form.

Jeremy

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