Parasubbotina eoclava Coxall et al. 2003 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 eoclava Coxall et al. 2003 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of wall: Reticulate Clavigerinella-type wall
texture, spinose in life.
Test morphology: Very low trochospiral,
somewhat laterally compressed, lobulate-petaloid in
outline, chambers globular and well separated with a
tendency for the final chamber to become slightly
radially elongated; in spiral view surface flattened so
that chambers of inner whorl are distinguishable; sutures
straight, slightly depressed; in umbilical view 4 chambers
in the final whorl, increasing rapidly in size, umbilicus
moderately small, narrow and deep, sutures straight and
slightly depressed; in edge view primary aperture a
moderately high arch, interiomarginal, umbilicalextraumbilical,
bordered by a well developed,
asymmetrical flaring lip that extends from the umbilicus
to the equatorial margin.
Size: Holotype maximum diameter 0.48 mm,
thickness 0.26 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
DISTINGISHING FEATURES. Parasubbotina
eoclava is characterized by its low trochospiral coiling,
Clavigerinella-type reticulate wall texture, an
interiomarginal umbilical-extraumbilical aperture
bordered by a broad, flaring apertural lip, and a tendency
toward radial extension of the last one or two chambers
which anticipates the clavate morphology of
Clavigerinella (from which it gets its name). It differs
from Parasubbotina inaequispira (Subbotina) in
possession of a distinctive flaring lip, more compressed
morphology and in the more rapid increase in chamber
size through the final whorl. It differs from
Clavigerinella eocanica in consistently showing low trochospiral rather than planispiral coiling, having less pronounced
clavate chambers, a more asymmetrical, and
lower arched aperture and a less-well developed apertural
lip. It is distinguished from Parasubbotina prebetica in
having lower trochospiral coiling, a flat spiral side, 4-
41/2 rather than 41/2-5 chambers in the final whorl,
chambers increasing gradually in size in the final whorl
that are considerable less bulbous than in P. prebetica, a
small umbilicus and a more equatorial position and
higher arch-morphology of the aperture.
DISCUSSION.- Blow (1979, p. 1 198- 1 199) remarked that the genus Clavigerinella appears in the record
"without any transitional forms in terms of apertural characteristics" but nevertheless "some specimens of early forms included in the taxon Subbotina inaequispira
(Subbotina). . . show some degree of radial elongation
of the chambers combined with an aperture which is
markedly asymmetrically placed with respect to the
umbilicus", and he suggested that such forms might be
ancestral. Toumarkine and Luterbacher (1985, fig. 22.19)
illustrated a so-called "G. inaequispira - C. eocanica
eocanica transition" which appears to be a sub-adult
specimen of C. eocanica. Coxall and others (2003)
erected the species Parasubbotina eoclava to include
some forms previously included in P. inaequispira that
they considered as distinct from the holotype
morphology of that taxon and show some transitional
features toward Clavigerinella, particularly the strongly
asymmetrical aperture with its broad lip, the low
trochospiral coiling, and the tendency for radially
extended chambers.
PHYLOGENETIC RELATIONSHIPS.- Parasubbotina
eoclava evolved from P. inaequispira in the
latest early Eocene and was ancestral to Clavigerinella
eocaenica (Coxall and others, 2003).
GEOGRAPHlC DISTRIBUTI0N.- Parasubbotina
eoclava is known from relatively high productivity
environments in the low to mid-latitudes, where it often
co-occurs with Clavigerinella spp. (Coxall and others,
2003).
STABLE ISOTOPE PALEOBIOL0GY.- This species
was recorded with more positive ò18O and more negative
ò13C than coexisting Turborotalia frontosa, indicating a
cold water sub-thermocline or upwelling environment
(Coxall and others, 2003). |
| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Globigerinidae
Genus Parasubbotina
Species Parasubbotina eoclava
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| Synonym list: |
Pearson et al. (2006):
p 1975 Clavigerinella? columbiana Petters. - McKeel & Lipps : p.258 pl. 4; fig. 6a, b (not pl. 3: fig. 8a-c =
Globorotaloides eovariablis Huber and Pearson n. sp.)
[lower middle Eocene Tyee Fm., Coast Ranges, Oregon].
[Not Petters, 19541.
p 1979 Subbotina inaequispira Subbotina. - Blow : p.1272 pl. 163; fig. 9-10 [Zone E8, Kane 9-Core 42,
Endeavour seamount, eastern North Atlantic Ocean]. [Not
Subbotina, 1953.]
2003 Parasubbotina eoclava Coxall et al.. - Coxall et al. : p.256 pl. 8; fig. 1-3 (holotype), 4-11 (paratype) [middle Eocene
Zone E8, ODP Hole 865B, Allison Guyot, equatorial
Pacific Ocean]
2004 Parasubbotina eoclava Coxall et al.. - Pearson et al. : p.36 pl. 1; fig. 14 [middle Eocene Zone E617, Tanzania]
2006 Parasubbotina eoclava Coxall et al.. - Pearson et al. : p.89 pl. 5.9; fig. 1-16 (Pl. 5.9, Figs. 1- 10: reillustration of holotype and
paratypes of Parasubbotina eoclava Coxall, Huber
and Pearson)
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| Specimen: |
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 517714
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 517715
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 517716
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| References: |
McKeel,D.R.. and Lipps,J.H. (1975):
Eocene and Oligocene planktonic foraminifera from the central and southern Oregon coast range . Journal of Foraminiferal Research Vol. 5 p. 1-5
Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp
Coxall,H.K..; Huber,B.T. and Pearson,P.N. (2003):
Origin and morphology of the Eocene planktonic foraminifer Hantkenina . Journal of Foraminiferal Research Vol. 33 p. 237-261
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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