Parasubbotina inaequispira Subbotina 1953 from: Pearson, P.N.Olsson, R.K.Hemleben, C.Huber, B.T.Berggren, W.A. (2006): Atlas of Eocene Planktonic Foraminifera. p. 1-513 | . |
Notice: This catalogue page may contain unedited data.
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Species Parasubbotina inaequispira Subbotina 1953 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of wall: Symmetrically to asymmetrically
cancellate (initially ruber/sacculifer-type wall texture but
becoming high porosity, reticulated sacculifer-type in
adult morphology and particularly in stratigraphically
younger morphotypes Clavigerinella-type with surface
thicking), normal perforate, spinose.
Test morphology: Test very low trochospiral,
globular, lobulate in outline, chambers globular; in spiral
view 4-41/2 globular, well separated chambers in final
whorl, increasing moderately in size, sutures moderately
depressed, straight, final chamber may be slightly
reduced in size relative to the penultimate chamber; in
umbilical view 4-41/2 globular, well separated chambers,
increasing moderately in size, sutures moderately
depressed, straight, umbilicus a moderate sized opening,
enclosed by surrounding chambers, aperture umbilical
to somewhat extraumbilical and directed towards the
anterior side of the test, bordered by a narrow continuous,
lip, ultimate chamber may be slightly reduced in size
relative to the penultimate chamber; in edge view
chambers globular in shape, well separated, aperture
visible as a low arch, bordered by a narrow lip.
Size: Maximum diameter of holotype 0.42 mm,
thickness 0.28 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
Subbotina (1953)
alluded to the "Globigerinella-like" coiling style of her
species and the small size of the inner whorl in
comparison to the outer whorl, the latter feature lending
the taxon its name. These features arise from the rapid
rate of chamber expansion and their low and slightly
irregular trochospiral arrangement, characters that help
assign the species to the genus Parasubbotina. The
species is distinguished by its lobulate, very low
trochospiral test with 4-41/2 chambers in the final whorl
and its anteriorly directed umbilical-extraumbilical
aperture.
The species has been widely identified in
previous literature, but often incorrectly so.
Parasubbotina inaequispira is distinguished from P.
varianta by being more openly coiled and having less
closely appressed chambers. It differs from Paragloborotalia griffinoides n. sp. principally in having much less dorso-ventral expansion and lacking the thick, prominent lip ofthat taxon. It differs from P. eoclava in lacking radially elongate chambers and a thick, flaring lip.
DISCUSSION.-
The holotype of Parasubbotina
inaequispira (Subbotina) is illustrated here in SEM for
the first time (Pl. 5.11, Figs. 1-3). Blow (1979, p. 1259)
regarded P. inaequispira as ancestral to Subbotina
crociapertura because of the tendency in P. inaequispira
"to produce apertural systems with a slightly expanded
to very slightly hooked distal part", which he believed
led to the distinctive hook-shaped aperture in S.
crociapertura. However, the majority of specimens he
illustrated to demonstrate this feature cannot be placed
in 19 inaequispira. In fact, Blow's images of inaequispira
show different types of wall texture that suggests mixing
of separate species. The specimens of S. crociapertura
from Tanzania illustrated by Blow, which includes the
holotype, have a bulloides-type wall texture whereas P
inaequispira has a ruber/sacculifer-type wall texture.
Some specimens of P. inaequispira illustrated by Blow
(his pl. 177, fig. 3; pl. 180, figs. 2, 3; pl. 185, fig. 9)
have a bulloides-type wall texture and may be
morphotypes of S. crociapertura.
Of particular interest are Blow's images of P.
inaequispira from Zones E7 and E8 from the Endeavour
Seamount in the North Atlantic Ocean (his pl. 15 1, figs. 5-7; pl. 163, figs. 4-10). These specimens show a fully
developed, high porosity, reticulated, sacculifer-type
wall texture that is characteristic of the genus
Clavigerinella, which apparently first developed in P.
inaequispira. Some of the specimens illustrated (his pl.
15 1, figs. 9 and 10) are placed in the intermediate species
Parasubbotina eoclava Coxall, Huber, and Pearson that
evolved from P. inaequispira and is believed to be
directly ancestral to Clavigevinella.
The type material of Globigerina
achtshacujmensis Khalilov and Globigerina
inaequispira var. transversa Khalilov has been viewed
by WAB and, despite the poor preservation, both are
clearly synonyms of P. inaequispira. The holotype and
three paratypes of Globigerina baylissi Samanta were
viewed by PNP. Samanta distinguished his taxon from
inaequispira by the supposed radial elongation of the
final chamber, but this feature is poorly developed and
falls within the range of variation here permitted to P.
inaequispira. More markedly radially elongate
parasubbotinids are assigned to P eoclava Coxall, Huber
and Pearson.
PHYLOGENETIC RELATIONSHIPS.-
Parasubbotina
inaequispira appears to have developed from
P. varianta (Subbotina) in the earliest Eocene. In turn it
gave rise to P. eoclava and P. griffinae in the latest early
Eocene.
GEOGRAPHIC DISTRIBUTION.-
Global in low to
mid latitudes. Parasubbotina inaequispira is a common
constituent of relatively high productivity environments
in the Eocene.
STABLE ISOTOPIC PALEOBIOL0GY.-
Relatively
heavy ò18O indicating cool water (H. K. Coxall,
unpublished data). |
| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Globigerinidae
Genus Parasubbotina
Species Parasubbotina inaequispira
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| Synonym list: |
Pearson et al. (2006):
1953 Globigerina inaequispira Subbotina. - Subbotina : p.84 pl. 6, fig. 1a-c (holotype), 4a-c [lower / middle Eocene Zone of conical
Globorotalia, Kuban River, northern Caucasus];
pl. 6, fig. 2a-3c [lower / middle Eocene Zone of conical Globorotalia, Foraminiferal layer, Series F, (bottom), Kuban River, northern Caucasus]
1973 Globigerina baylissi Samanta. - Samanta : p.436 pl. 2; fig. 4-6 [middle Eocene Truncorotaloides rohri Zone, Rakhi Nala lacking radially elongate chambers and a thick, flaring
section, Pakistan]
1975 Globigerina inaequispira Subbotina. - Stainforth et al. : p.191 fig. 54 1a-c [from Subbotina, 1953];
fig. 54 2a-c [reillustration of holotype];
fig. 54 3-5
[middle Eocene, no locality given]
p 1979 Subbotina inaequispira Subbotina. - Blow : p.1272 pl. 151, fig. 5-7 [lower Eocene Zone E7, KANE
9-Core 42, Endeavour Seamount, eastern North Atlantic Ocean];
pl. 163, fig. 4-8 [middle Eocene Zone E8, KANE
9-Core 42, Endeavour Seamount, eastern North Atlantic Ocean];
pl. 180, fig. 1, 4-7 [middle Eocene Zone E9,
DSDP Hole 2 l A, Gulf of Mexico];
pl. 191, fig. 7 [middle
Eocene Zone E12, Sample RS.311, Kilwa area,
Tanzania]
2000 Subbotina inaequispira Subbotina. - Warraich et al. : p.299 fig. 18: 6-8 [Dungan Fm., Sulaiman Range, Pakistan]
2001 Subbotina inaequispira Subbotina. - Warraich & Ogasawara : p.48 fig. 13: 17-19 [Zone E5, Dungan Fm.,
Sulaiman Range, Pakistan]
2006 Parasubbotina inaequispira Subbotina. - Pearson et al. : p.93 pl. 5.11; fig. 1-15 (Pl. 5.11, Figs. 1-3: new SEMs of holotype of
Globigerina inaequispira Subbotina)
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| Specimen: |
VNIGRI collections, St. Petersburg, Inventory number: 3069
VNIGRI collections, St. Petersburg, Inventory number: 4016
VNIGRI collections, St. Petersburg, Inventory number: 4017
VNIGRI collections, St. Petersburg, Inventory number: 4018
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| References: |
Subbotina,N.N. (1953):
Iskopaemye foraminifery SSSR (Globigerinidy, Khantkenininidy i Globorotaliidy) . Trudy Vsesoyznogo Nauchno-Issledovatel'skogo Geologo-razvedochnogo Instituta (VNIGRI) Vol. 76 p. 296
Khalilov,D.M. (1956):
O pelagicheskoy faune foraminifer Paleogenovykh otlozheniy Azerbaydzhana . Trudy Instituta Geologii, Akademiya Nauk Azerbaydzhanskoy SSR Vol. 17
Samanta,B.K. (1973):
Planktonic foraminifera from the Palaeocene-Eocene succession in the Rakhi Nala, Sulaiman Range, Pakistan . British Museum Natural History Bulletin Vol. 22(6) p. 436
Stainforth,R.M.; Lamb,J.L.; Luterbacher,H.P.; Beard,J.H. and Jeffords,R.M. (1975):
Cenozoic planktonic foraminiferal zonation and characteristics of index forms . Paleontological ContributionsArticle 62 p. 425
Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp
Toumarkine,M. and Luterbacher,H.P. (1985):
Paleocene and Eocene Planktic Foraminifera.
In: Plankton Stratigraphy p. 87-154
Warraich,M.Y..; Ogasawara,K.. and Nishi,H.. (2000):
Late Paleocene to early Eocene planktonic foraminiferal biostratigraphy of the Dungan Formation, Sulaiman Range, Central Pakistan . Paleontological Research Vol. 4 p. 275-301
Warraich,M.Y.. and Ogasawara,K.. (2001):
Tethyan Paleocene-Eocene planktic foraminifera from the Rakhi Nala and Zinda Pir land sections of the Sulaiman Range, Pakistan . Science Reports of the Institute of Geoscience University of Tsukuba, section B Vol. 22 p. 1-59
Pearson,P.N.; Nicholas,C.J..; Singano,J.M..; Bown,P.R..; Coxali,H.K..; van Dongen,B.E..; Huber,B.T.; Karega,A..; Lees,J.A..; Misaky,E..; Pancost,R.D..; Pearson,M.. and Roberts,A.P.. (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 Vol. 39 p. 25-62
Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006):
Atlas of Eocene Planktonic Foraminifera. p. 1-513
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