pforams@mikrotax - Praemurica pseudoinconstans

Citation: Praemurica pseudoinconstans (Blow 1979)

Basionym: Globorotalia (Turborotalia) pseudoinconstans

Synonyms:

Globorotalia pseudobulloides (Plummer).—Loeblich and Tappan, 1957a: 192, pl. 40: fig. 9a-c [paratype, Pine Barren Mbr., Clayton Fm., Alabama] [in part]. [Not Plummer, 1926.]
Globorotalia (Turborotalia )pseudoinconstans Blow, 1979:1105, pl. 67: fig. 4 [holotype: Zone Pa, DSDP Hole 47.2/11/3: 148-150 cm], pl. 67: fig. 3 [paratypes: Zone Pa, DSDP Hole 47.2/11/3: 148-150 cm], pl. 69: fig. 4 [paratypes: Zone Pl, DSDP Hole 47.2/11/3: 0-5 cm; Shatsky Rise, northwestern Pacific Ocean].
"Morozovella" inconstans (Subbotina).—Huber, 1991c:46l, pl. 3: figs. 11, 12 [Zone A P l b , ODP Hole 738C/19R: 365.22 mbsf; Kerguelen Plateau, southern Indian Ocean], [Not Subbotina, 1953.]
Praemurica pseudoinconstans (Blow).—Olsson, Hemleben, Berggren, and Liu, 1992:202, pl. 6: figs. 1,4 [Zone Pa, Clayton Basal Sands, Millers Ferry, Alabama]: figs. 2, 3, 5-8 [Zone Pla, Pine Barren Mbr., Clayton Fm„ Millers Ferry, Alabama], [Olsson et al. 1999]

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 P. pseudoinconstans, 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]

Distinguishing features:
Parent taxon (Praemurica): Test very low trochospiral, usually 5-6, globular to oval chambers in last whorl, periphery lobulate;
Wall non-spinose, weakly cancellate;
This taxon: Like P. taurica but with increased rate of expansion of the final few chambers; also apertural lip less pronounced.

Description

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]

Biogeography and Palaeobiology

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)

No data available. [Olsson et al. 1999]
Aze et al. 2011 ecogroup 2 - Open ocean mixed-layer tropical/subtropical, without symbionts; based on comparison with other species of the genus.

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]

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

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. 120: 551-568. gs

Bermudez, P. J. (1961). Contribucion al estudio de las Globigerinidea de la region Caribe-Antillana (Paleoceno-Reciente). Editorial Sucre, Caracas. (3): 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. 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 O

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. (85): 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 Vsesoyuznego Neftyanogo Nauchno-Issledovatel'skogo Geologo-Razvedochnogo Instituta (VNIGRI). 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

Comments (2)

Chengjie Liu(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?

7 February 2019 15:00

Jeremy Young(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

7 February 2019 19:06

test outline:	Subcircular	chamber arrangement:	Trochospiral	edge view:	Equally biconvex	aperture:	Umbilical
sp chamber shape:	Inflated	coiling axis:	Low	periphery:	N/A	aperture border:	Thick lip
umb chbr shape:	Inflated	umbilicus:	Wide	periph margin shape:	Broadly rounded	accessory apertures:	Relict
spiral sutures:	Strongly depressed	umb depth:	Deep	wall texture:	Pore mounds	shell porosity:	Finely Perforate: 1-2.5µm
umbilical or test sutures:	Strongly depressed	final-whorl chambers:	6-7	N.B. These characters are used for advanced search. N/A - not applicable

Praemurica pseudoinconstans

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

References:

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Comments (2)